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Aylwin
2005-04-26, 14:05
I just received my SB2 last week. What a joy! Up and running in 2 mintues, no manual needed. Anyway, I figured I should join the forums too now that I'm an owner. I must admit though that I was surprised to see an Audiophiles forum. I bought my SB2 primarily to stream music anywhere in the house except the audio room. And after a quick look at some threads I said to myself, "people can't seriously think this is an audiophile device, can they?" So I decided to run a few tests of my own.

I ripped a few choice tracks to WAV using EAC and hooked up my SB2 to the audio system and then compared the playback of the WAVs against the CDs. The result, just as I thought. The SB2 can't compete. Then, I connected the SB2 to the same DAC my CD changer is connected to. This time I was pleasantly surprised. It was pretty close, with the CD changer + DAC probably just marginally better then SB2 + DAC. However, against a "proper" CD player the differences were more noticeable compared with the SB2 + DAC combination. Not a huge difference though.

In my opinion, the SB2 paired with a good DAC will produce very good sound. Of audiophile quality? Possibly close enough. Not enough to make me get rid of my CD player though. At least that's how it is on my system.

How is it on yours?

Regards,
Aylwin

By the way, my DAC is an old MSB LinkDAC III w/ 96KHz upsampling. Perhaps with a better DAC the combination would've given the CD player (Marantz SA-8400) a serious run for its money.

Mitch Harding
2005-04-26, 14:56
I'm curious -- did you do your comparisons blind?

On 4/26/05, Aylwin <Aylwin.1o46in (AT) no-mx (DOT) forums.slimdevices.com> wrote:
>
> I just received my SB2 last week. What a joy! Up and running in 2
> mintues, no manual needed. Anyway, I figured I should join the forums
> too now that I'm an owner. I must admit though that I was surprised to
> see an Audiophiles forum. I bought my SB2 primarily to stream music
> anywhere in the house -except- the audio room. And after a quick look
> at some threads I said to myself, "people can't seriously think this is
> an audiophile device, can they?" So I decided to run a few tests of my
> own.
>
> I ripped a few choice tracks to WAV using EAC and hooked up my SB2 to
> the audio system and then compared the playback of the WAVs against the
> CDs. The result, just as I thought. The SB2 can't compete. Then, I
> connected the SB2 to the same DAC my CD changer is connected to. This
> time I was pleasantly surprised. It was pretty close, with the CD
> changer + DAC probably just marginally better then SB2 + DAC. However,
> against a "proper" CD player the differences were more noticeable
> compared with the SB2 + DAC combination. Not a huge difference
> though.
>
> In my opinion, the SB2 paired with a good DAC will produce very good
> sound. Of audiophile quality? Possibly close enough. Not enough to
> make me get rid of my CD player though. At least that's how it is on
> my system.
>
> How is it on yours?
>
> Regards,
> Aylwin
>
> --
> Aylwin
>

Christian Pernegger
2005-04-26, 15:19
> I [...] compared the playback of the WAVs against the CDs.
> The result, just as I thought. The SB2 can't compete. Then, I
> connected the SB2 to the same DAC my CD changer is connected to.

Somehow I have problems imagining a CD changer as a high-end transport.

Maybe someone should open a SB2 ABX site with a guide for people to follow,
and then publish the results.

C.

pfarrell
2005-04-26, 15:21
On Tue, 2005-04-26 at 16:56 -0500, Mitch Harding wrote:
> I'm curious -- did you do your comparisons blind?

And nearly as important, with the gain matched to well under a dB?


--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

shermoid
2005-04-26, 16:34
hi there,

i AM a professed audiophile, and actually purchased the SB2 as a replacement device for mega cd changers, which are far from audiophile quality. i was getting tired of hearing mediocre sound out of my high-end system, and needed a multi-cd audiophile solution. so, i chose the the SB2 and FLAC encoded discs.

however, there is a catch here: you must use FLAC as your encoding - not MP3!!!

FLAC, as you all probably know, stands for "free lossless audio CODEC". i chose the SB2 specifically because it decodes FLAC encoded music streams. not only by definition, but also by ear, the decoded music stream has exactly the same audio quality as the original cd. i did make the SB2 use a fixed output level, allowing the SB2's internal d-to-a converter to deliver the highest quality audio it can.

later, as finances allow, i'll get a mcintosh mda1000 d-to-a converter, and run the digital output of the SB2 into that for even better audio quality.

i did an A/B test this past weekend, when i received my SB2. i FLAC-encoded a cd, and then had the original cd playing in a mcintosh cd player, while the same music was coming through the squeezebox. i literally could not tell the difference between the two! and, that has everything to do with FLAC. i have done the same test with an MP3 encoded cd - even at 320k bits. the MP3 sounds like "recorded" music. the original cd sounds like the musicians are right in my living room. but with FLAC, there were no differences my ear could detect. of course, FLAC files are much, much larger than MP3 files. my average compression ratio right now (after about 30 ripped cds) is about 66%. FLAC files only are 33% smaller than the original cd.

so, i am truly impressed with the d-to-a converter in the SB2 as well as the SB2 itself. i've ordered a 1.2 terabyte network attached storage device, and am about to rip all 1,000+ cds in my collection, and commit them to FLAC files on disc. i'm keeping the originals, just in case of a big disc crash! :-) maybe a tape backup unit would come in handy here ...

best,
-sherman

sleepysurf
2005-04-26, 19:58
I'm doing precisely the same thing. Ripping all my CD's (with EAC) to flac stored on a 300 GB Buffalo Linkstation. So far, I hear little (if any) difference comparing the original CD (albeit played on older Sony ES series CD changer, or Toshiba SD-3750 DVD player) vs. SB2 with optical out, all into a Yamaha RX-V1000 (with admittedly ?? DAC). I intend to eventually replace the Yamaha with a higher-end pre/pro. I've already pulled the Sony changer out of my system. I have Digital Coax cables on order, and will next compare the SB2 Analog RCA vs. Optical vs. Digital Coax. I'm also patiently waiting for somebody to conduct a REAL ABX listening session.

Aylwin
2005-04-27, 00:25
Admittedly, my testing wasn't very scientific. So the comparisons weren't blind and very subjective. No proper level matching either as I didn't have an SPL meter on hand. The audio format used for testing the SB2 was WAV as it is native PCM.

My CD changer, Pioneer PD-F1007, is far from being a high end transport. But SB2 vs. Pioneer + DAC, even without accurate level matching, the Pioneer + DAC beats the SB2. I tried playing with volume controls and it made no difference whether one was louder than the other.

As for SB2 + DAC vs. Pioneer + DAC, I believe the output levels were close enough (if not the same). This was a much closer fight. Very subjective on my part so I probably can't guarantee I'd pick my CD changer over the SB2 if the test was blind.

With the Marantz SA-8400 vs SB2 + DAC, again, the problem is accurate level matching. Nevertheless, I believe I can tell the difference.

In my opinion, the SB2 is a very valid alternative to a mega CD changer. Via the analog outputs, I believe the SB2 will easily beat the CD changer. With a DAC, it's probably difficult to tell the difference in sound quality but the SB2 definitely has the huge advantage in features. With a very good DAC, it probably has the potential to rival many entry to mid level audiophile cd players.

Please don't get me wrong. I'm not saying that "SB2" and "Audiophile" don't go together. It was just my initial assumption and now I'm not so sure anymore. I believe the SB2 definitely has potential and I'm very happy with it. I was just trying to describe how I believe it performs in my system. And I'm also interested in hearing how it is in other people's systems as well.

Aylwin

Patrick Dixon
2005-04-27, 03:06
As for SB2 + DAC vs. Pioneer + DAC, I believe the output levels were close enough (if not the same).I'd be suprised if they weren't identical, since it's the DAC that determines the gain in both cases - and it's the same.

ackcheng
2005-04-27, 06:49
Theoretically, SB2 should be able to produce bit accurate information as it has no mechanical part. So, it should be able to replace the best transport.

Aylwin
2005-04-27, 11:03
I'd be suprised if they weren't identical, since it's the DAC that determines the gain in both cases - and it's the same.I agree. I just wasn't able to check with any measuring device. At least the levels shouldn't have changed during WAV conversion.


Theoretically, SB2 should be able to produce bit accurate information as it has no mechanical part. So, it should be able to replace the best transport.Perhaps theoretically. But digital audio has 2 components: bits and clocking. Even if the 1's and 0's are read accurately, synchronisation may still be an issue. High end transports use the best oscillators and other components related to clocking to make sure the bits are transmitted with the most accurate timing possible.

I'm actually very intrigued and interested in how the data is transferred to the SB2. Considering that the quality is very good, I'm sure a lot of thought and effort has gone into clock recovery at the receiving end. Or maybe the solution is actually very simple. Does anyone know?

earthbased
2005-04-27, 11:31
hi there,

[snip]

i've ordered a 1.2 terabyte network attached storage device, and am about to rip all 1,000+ cds in my collection, and commit them to FLAC files on disc. i'm keeping the originals, just in case of a big disc crash! :-) maybe a tape backup unit would come in handy here ...

best,
-sherman

What storage device are you ordering? I am going to start a FLAC library and will need at least 500 GB to start. Preferably, I want a RAID 5 solution so I don't easily lose my FLACs.

John Stimson
2005-04-27, 11:54
Alwyn, the data is transmitted to the SB2 via TCP/IP, which is asynchronous to the data stream. I believe that the SB2 has a memory buffer to store the data, and sends "more/stop/more/stop" signals to the server to keep the buffer full. Then the data is pulled out of the buffer using a clock generated within the SB, and sent over the SPDIF output using that clock. So it works very much like a CD player as a transport.

The SB2 analog outputs seem to be similar to the analog outputs on my CAL CL-2500DVD (the successor to the CL-20/25 which rated Class B in Stereophile) so I have little hesitation in calling it an "Audiophile" device, expecially compared to the original, and likely all the other network players on the market.

I did find the MSB Nelson Link III to be slightly better sounding, and with upsampling turned on even a bit better than that. I'll be doing some tests with a Musical Fidelity A3.24 next week, I hope.

Skoff, Robert P.
2005-04-27, 12:13
-----Original Message-----
From: audiophiles-bounces (AT) lists (DOT) slimdevices.com
[mailto:audiophiles-bounces (AT) lists (DOT) slimdevices.com] On Behalf Of
audiophiles-request (AT) lists (DOT) slimdevices.com
Sent: Wednesday, April 27, 2005 3:00 PM
To: audiophiles (AT) lists (DOT) slimdevices.com
Subject: audiophiles Digest, Vol 1, Issue 23

Send audiophiles mailing list submissions to
audiophiles (AT) lists (DOT) slimdevices.com
Great thread. I'd also like some advice about what external hard drive
to get to store my FLAC files. What is a "Raid 5" solution? Is there
some advantage to using a Terastation over a plain old external hard
drive connected to my PC via Firewire?

Thanks!

earthbased
2005-04-27, 12:24
-----Original Message-----
From: audiophiles-bounces (AT) lists (DOT) slimdevices.com
[mailto:audiophiles-bounces (AT) lists (DOT) slimdevices.com] On Behalf Of
audiophiles-request (AT) lists (DOT) slimdevices.com
Sent: Wednesday, April 27, 2005 3:00 PM
To: audiophiles (AT) lists (DOT) slimdevices.com
Subject: audiophiles Digest, Vol 1, Issue 23

Send audiophiles mailing list submissions to
audiophiles (AT) lists (DOT) slimdevices.com
Great thread. I'd also like some advice about what external hard drive
to get to store my FLAC files. What is a "Raid 5" solution? Is there
some advantage to using a Terastation over a plain old external hard
drive connected to my PC via Firewire?

Thanks!

RAID 5 uses at minimum 3 drives to stripe data and parity info across them. If one drive fails, the lost data can be re-constructed in real-time until the drive is replaced. I just read about the TERASTATION; looks like that is my solution for my FLAC files.

Dan Sully
2005-04-27, 12:35
* earthbased shaped the electrons to say...

>RAID 5 uses at minimum 3 drives to stripe data and parity info across
>them. If one drive fails, the lost data can be re-constructed in
>real-time until the drive is replaced. I just read about the
>TERASTATION; looks like that is my solution for my FLAC files.

The Terastation has abysmal throughput. I suggest you look elsewhere.

-D
--
"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." - Benjamin Franklin

Aylwin
2005-04-27, 12:37
Thanks for the feedback and info, John! I'll be interested to hear how it goes with the A324 which I think is a very good DAC.

As for the data transmission, I still have quite a few questions. All the streaming applications I know of use UDP. I wonder how they can implement it using TCP. TCP would have error correction and therefore provide accurate data. But I imagine that would require huge buffers and cause considerable delay in start up. And it's still no guarantee. Interesting stuff...

Christian Pernegger
2005-04-27, 12:47
> The Terastation has abysmal throughput. I suggest you look elsewhere.

Thanks for saving my money :)

Any idea why? Linux RAID-5 is not that bad and it does have a Gbit interface.


C.

Dan Sully
2005-04-27, 12:56
* Christian Pernegger shaped the electrons to say...

>> The Terastation has abysmal throughput. I suggest you look elsewhere.
>
>Thanks for saving my money :)
>
>Any idea why? Linux RAID-5 is not that bad and it does have a Gbit interface.

I believe it's the disk controller. Sean had one and returned it.

And yes - Linux RAID5 (especially the latest 2.6 kernels with bitmapping) is
quite good. That's what I run on my home server.

-D
--
I'm really looking forward to this hangover.

John Stimson
2005-04-27, 13:43
I am not absolutely certain that slimserver uses TCP, but have read that assertion on the lists. I was told that slimserver works as single-cast TCP, not UDP which is broadcast. In any case, there is no clock information sent over the LAN connection.

As for storage, I use mirrored (RAID1) drives in my Linux server. I guess for the purpose of storing audio, RAID5 (slow) with modern drives would be more than adequate assuming I can get more drives of the same model I already have.

JohnnyLightOn
2005-04-27, 14:17
Aylwin, for best sound quality it's important that your Squeezebox is set (via SlimServer) to fixed volume control and also to no limit bitrate.

If the volume is set to adjustable, or the bit rate is limited to 320, you will not be getting the best sound.

Thanks for sharing your SB2 experience!

max.spicer
2005-04-27, 14:39
All the streaming applications I know of use UDP. I wonder how they can implement it using TCP. TCP would have error correction and therefore provide accurate data. But I imagine that would require huge buffers and cause considerable delay in start up. And it's still no guarantee. Interesting stuff...
I think UDP is used for local network traffic and TCP only if you want to connect over the internet. I could very likely be wrong, however!

windguy2
2005-04-27, 14:54
Thanks for the review, any chance of trying battery power (4 AA
rechargeable(1.2volt) batteries would work for a short time) to see if
it substantially improves the analogue output.

Mike.

On Apr 27, 2005, at 12:54 PM, John Stimson wrote:

>
> Alwyn, the data is transmitted to the SB2 via TCP/IP, which is
> asynchronous to the data stream. I believe that the SB2 has a memory
> buffer to store the data, and sends "more/stop/more/stop" signals to
> the server to keep the buffer full. Then the data is pulled out of the
> buffer using a clock generated within the SB, and sent over the SPDIF
> output using that clock. So it works very much like a CD player as a
> transport.
>
> The SB2 analog outputs seem to be similar to the analog outputs on my
> CAL CL-2500DVD (the successor to the CL-20/25 which rated Class B in
> Stereophile) so I have little hesitation in calling it an "Audiophile"
> device, expecially compared to the original, and likely all the other
> network players on the market.
>
> I did find the MSB Nelson Link III to be slightly better sounding, and
> with upsampling turned on even a bit better than that. I'll be doing
> some tests with a Musical Fidelity A3.24 next week, I hope.
>
>
> --
> John Stimson
>

Doug Porter
2005-04-27, 15:10
John Stimson <John.Stimson.1o6010 (AT) no-mx (DOT) forums.slimdevices.com> wrote:
>
> I am not absolutely certain that slimserver uses TCP, but have
> read that assertion on the lists.

The new protocol (introduced in late-2003 iirc) is TCP-based.
The original protocol used with the SliMP3 was implemented with
UDP though.

--
Doug Porter <dsp (AT) dsp (DOT) name>

Doug Porter
2005-04-27, 15:12
> I think UDP is used for local network traffic and TCP only if
> you want to connect over the internet. I could very likely be
> wrong, however!

Either can be used locally or over the Internet. DNS is the best
example of a service used across the Internet that is
predominately UDP.

--
Doug Porter <dsp (AT) dsp (DOT) name>

earthbased
2005-04-28, 07:00
* earthbased shaped the electrons to say...

>RAID 5 uses at minimum 3 drives to stripe data and parity info across
>them. If one drive fails, the lost data can be re-constructed in
>real-time until the drive is replaced. I just read about the
>TERASTATION; looks like that is my solution for my FLAC files.

The Terastation has abysmal throughput. I suggest you look elsewhere.

-D
--
"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." - Benjamin Franklin

Is the throughput bad on both read and write or just write? It can't saturate a 100Mbps?

What else do you suggest I look at for portable RAID solution?

Dan

dean
2005-04-28, 09:25
On Apr 28, 2005, at 7:00 AM, earthbased wrote:
> What else do you suggest I look at for portable RAID solution?
I'd recommend an inexpensive tower PC, an inexpensive serial ATA
card, and put 3 or more serial ATA drives in it.

The entry level dell servers are quite reliable and cheap.

Then it up with a recent linux distribution. It's a bit more work to
configure, but gives you the most flexibility with regards to
software installs.

It's not _that_ portable, but it should do what you need.

pfarrell
2005-04-28, 10:10
On Thu, 2005-04-28 at 07:00 -0700, earthbased wrote:
> What else do you suggest I look at for portable RAID solution?

This sounds like an oxymoron to me. Why would you want portability
in a Raid system, which are usually big, expensive, and placed in
controlled environments?


--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

earthbased
2005-04-28, 13:11
On Thu, 2005-04-28 at 07:00 -0700, earthbased wrote:
> What else do you suggest I look at for portable RAID solution?

This sounds like an oxymoron to me. Why would you want portability
in a Raid system, which are usually big, expensive, and placed in
controlled environments?


--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

RAID to guard against losing my music collection and portable so I can easily take it with me on my travels.

pfarrell
2005-04-28, 13:23
On Thu, 2005-04-28 at 13:11 -0700, earthbased wrote:
> pfarrell Wrote:
> > This sounds like an oxymoron to me.
>
> RAID to guard against losing my music collection and portable so I can
> easily take it with me on my travels.

Wow, I'd never have thought of that.
Sounds like overly restricting the solution space to me.

If you only have 200 GB of music, you could always get a SFF shuttle
system and put two disks and use software raid.

I might see going FLAC on raid on a server at home, and then
downloading MP3s to a portable device.

YMMV
--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

dean
2005-04-28, 13:35
On Apr 28, 2005, at 1:11 PM, earthbased wrote:
> RAID to guard against losing my music collection and portable so I can
> easily take it with me on my travels.

Consider getting two inexpensive single-drive servers and leaving one
at home and taking one with you on the road.

Back up when you get home and then if you lose one, you'll have a
spare at the other location.

Aylwin
2005-04-29, 00:20
Aylwin, for best sound quality it's important that your Squeezebox is set (via SlimServer) to fixed volume control and also to no limit bitrate.Thanks for the tip! I hadn't noticed those options before. When I checked, the volume control wasn't fixed. This probably explains why CD changer + DAC was slightly better than SB2 + DAC during my testing. So now, I guess the SB2 is even better than I initially thought!

I might try to do some more tests when I have time. Maybe even try to convince the wife to help me with blind tests. :)


And Doug, thanks for the additional info. Very interesting stuff!

Christian Pernegger
2005-04-29, 01:50
> RAID to guard against losing my music collection

Errm ... it's called backup.

RAID-5 guards you from having to restore the backup in casde of a
single point failiure (one HD) and is practical in cases where
downtime should be minimized or a backup is just not practical (my 1.4
TB of stored TV recordings)

> and portable so I can easily take it with me on my travels.

Others have reported success with Boffalo Linkstations ... just buy
two and have them sync overnight.

C.

earthbased
2005-04-29, 09:28
>

Others have reported success with Boffalo Linkstations ... just buy
two and have them sync overnight.

C.

I looked at the manual for the LinkStation and didn't see a sync function. How is this done?

Dan

Christian Pernegger
2005-04-29, 10:17
> > Others have reported success with Boffalo Linkstations ... just buy
> > two and have them sync overnight.

> I looked at the manual for the LinkStation and didn't see a sync
> function. How is this done?

It has a built-in FTP server.

You'd have to hack one of them to install slimserver anyway. Might as
well put on a little mirroring script on it at that time. rsync would
be better of course but that would require hacking both boxes.

C.

John Stimson
2005-05-03, 16:42
Thanks for the feedback and info, John! I'll be interested to hear how it goes with the A324 which I think is a very good DAC.I have a preliminary report. It's not the best test, since I had to get up off the couch to change between sources.

Levels sounded identical when switching between sources while sitting in front of the right speaker -- all of the commonly used Burr Brown PCM series DACs seem to have the same output levels, which isn't surprising.

The A3.24 was connected to the optical output, and the Link III was connected to the coaxial output. The A3.24 had tighter bass. It also had the same overall sound that I remembered hearing from a Musical Fidelity class A integrated amp almost a decade ago...which is interesting, because the CD source in that rig could not have been nearly as high quality as the A3.24 is. Perhaps Musical Fidelity's designers like to add a particular coloration that gives their gear a signature sound, or maybe it's just all in my head. In either case, the A3.24 sounds excellent.

Sometime later this week I may have a friend switch the sources for me for an instantaneous comparison.

Aylwin
2005-05-04, 01:57
Nice! Thanks for sharing!

It's been ages though since I've last auditioned any Musical Fidelity equipment so I can't really comment anymore on the sound. Still, I wouldn't be surprised if they designed their products to produce a certain signature sound. I guess that's not necessarily a bad thing. Although personally, I prefer my components to be more on the neutral side.

Christian Pernegger
2005-05-04, 15:30
> The Terastation has abysmal throughput.

I just got my hands on a regular LinkStation 2 250GB, which I wanted
to use for daily backups.

FTP PUT 5-6MB/s - That's bad even for a very old/cheap IDE disk.
SMB-mounted 1-3MB/s - slooow and had issue with file modification
dates, permissions
and ownership. rsync worked, mor or less.
CIFS-mounted 1-3MB/s - still slow, but with unix extensions now.
rsync refuses to work
because of timestamp issues.

The rsync stuff I might have been able to work around, but the speed
is just beyond bad. What's more, after an afternoon of tinkering I
don't feel like opening it for proper access anymore. This one goes
back ...

People are running slimserver on these? Is it just the MIPS based ones
that suck?

C.

Craigaz
2005-05-04, 18:14
I bought my SB2 as a "toy" but decided to connect it to my high-end sytem just for giggles. My system consists of:

Accuphase DP-100 transport
Accuphase DC-101 DAC
Krell FPB-350MCX Monoblocks
Wilson Audio Watt/Puppy 5.1's
Loads of acoustic room treatments

I connected the digital output of the SB2 into my DAC for this test.

I ripped a few of my favorite CD's in FLAC format and began comparing the original in my transport to the SB2 - un freakin' believable! I am so pleased that I have started "ripping" all of my collection!

There is a slight difference between the transport and the SB2 - but is so minimal, I will keep my "favorite" CD's on hand and rip everything else.

Thanks Slimdevices for my new toy!

Craig

windguy2
2005-05-04, 19:04
Possible you could compare the analogue output? I'm interested in the
comparison to the high end DAC.

Thanks,
Mike.

On May 4, 2005, at 7:14 PM, Craigaz wrote:

>
> I bought my SB2 as a "toy" but decided to connect it to my high-end
> sytem just for giggles. My system consists of:
>
> Accuphase DP-100 transport
> Accuphase DC-101 DAC
> Krell FPB-350MCX Monoblocks
> Wilson Audio Watt/Puppy 5.1's
> Loads of acoustic room treatments
>
> I connected the digital output of the SB2 into my DAC for this test.
>
> I ripped a few of my favorite CD's in FLAC format and began comparing
> the original in my transport to the SB2 - un freakin' believable! I am
> so pleased that I have started "ripping" all of my collection!
>
> There is a slight difference between the transport and the SB2 - but
> is so minimal, I will keep my "favorite" CD's on hand and rip
> everything else.
>
> Thanks Slimdevices for my new toy!
>
> Craig
>
>
> --
> Craigaz
>

pfarrell
2005-05-04, 19:44
On Wed, 2005-05-04 at 20:04 -0600, windguy2 wrote:
On May 4, 2005, at 7:14 PM, Craigaz wrote:
> >- un freakin' believable!
>
> Possible you could compare the analogue output? I'm interested
> in the comparison to the high end DAC.

I'm not Craigaz, but I am wondering what you expect to find
in your comparison.

The SB2 is a $200 device (wired) with a display, case,
computer and DAC.

I would expect it to do no better than "OK" against a
moderate expensive DAC. For example, the Benchmark DAC-1
is a $1000 box with just the DAC and case. It is very good,
I have one, but you can spend ten times that much
for a "audiophile" DAC, maybe even more.

If the SB2 is even "pretty good" as a DAC, I sure
don't expect it to be as-good-as or better) than something like
a Benchmark or Larvy or Crane -- which are all
in the "about a grand" range.

--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

radish
2005-05-04, 20:32
The SB2 is a $200 device (wired) with a display, case,
computer and DAC.

I would expect it to do no better than "OK" against a
moderate expensive DAC. For example, the Benchmark DAC-1
is a $1000 box with just the DAC and case. It is very good,
I have one, but you can spend ten times that much
for a "audiophile" DAC, maybe even more.

All of which seems to imply you subscribe to the belief that something is better simply because it's more expensive. I'm not saying these DACs aren't great, I've never heard any of them, but if I sold you a squeezebox for $1000 it wouldn't magically sound any better. The components themselves typically aren't that expensive, what you're paying for is the design, the precision manufacturing, etc. How much difference those make to the sound (and whether that difference is positive or negative) is entirely up for discussion IMHO :)

pfarrell
2005-05-04, 21:14
On Wed, 2005-05-04 at 20:32 -0700, radish wrote:
> All of which seems to imply you subscribe to the belief that something
> is better simply because it's more expensive.

I'm saying nothing of the sort.
But if an item is well priced to reflect the
costs of its design and parts and marketing
and all that, then I would expect
something that costs five to ten times as
much to sound better. [Unless
we start talking about mass production,
and nothing that SlimDevices sells
is mass production]

Not five to ten times better, but better.

The critical "fly in the ointment"
for audiophiles is that there are very
few audiophiles in the world compared to
the number of folks listening to music.

With nearly anything manufactured, the number
of units can change all the other numbers,
if you can spread the basic costs
over millions of units. While silicon
CPUs and memory are obvious, in the audio
world the tens of millions of "Creative Sound
Blaster" units had a massive impact. The sound
you get from a $50 PC sound card was priced
above gold just 15 years ago. Same with CD
player transports. The quality in a $50 DVD reader
is amazing, and the numbers sold for PCs
have yielded DVD players that are nearly free.

Nothing in the audiophile world has unit
sales in the same league. Same with
professional recording studio gear.
Nearly all of it costs huge amounts
more than mass market stuff, because
the pro engineers and audiophiles are
willing to pay for improvements that
the mass market won't support.

And don't forget that all this stuff
is subjective. Once you have a $1000 DAC
connected with $200 cables to your amp,
your brain is not likely to say that the
DAC in a squeesebox is equal.

While the ABX random tests are pretty
easy to do between things like encoders,
they get very hard, if not impossible
to do with things like amps, dacs and
wires. Mostly because getting the levels
exactly the same is critical, human
brains always say that louder signals
are better.


--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

windguy2
2005-05-05, 07:01
The SB2 is using a non oversampling PCM1748, a large memory buffer and
a couple crystals dedicated to 44.1 and 48khz.

Quality DAC chip prices range from about $1 to $24 - doesn't seem to be
any relationship between the price of a standalone DAC and the DAC
chip(s) used. Like everything in audio it is the implementation and
attention to detail(or sometimes luck?) that seems to determine the
quality of the end result.

I haven't heard the Benchmark DAC1, but it is a class A stereophile
product and highly rated. It includes volume, multiple digital inputs,
variable analogue output, dedicated headphone outputs etc - remove all
those options and maybe they could sell it as a standalone DAC for much
much less.

Standalone DAC's introduce other issues such as cable quality -
clocking issues etc. Even the Benchmark DAC1 with it's huge jitter
rejection ability apparently sounds different with different transports
(I believe that even though it reduces jitter transports create jitter
at different frequencies and that's why they sound different since it
is impossible to remove all jitter)

The reason I am interested in the analogue output of the SB2 is that I
believe it could sound very good because it is a relatively simple
design. If it could come even close to something like the Benchmark
would inspire me to build a battery power supply and look into other
modifications. If not, I will probably end up with the Benchmark or
similar standalone DAC.

Mike.




On May 4, 2005, at 8:44 PM, Pat Farrell wrote:

> On Wed, 2005-05-04 at 20:04 -0600, windguy2 wrote:
> On May 4, 2005, at 7:14 PM, Craigaz wrote:
>>> - un freakin' believable!
>>
>> Possible you could compare the analogue output? I'm interested
>> in the comparison to the high end DAC.
>
> I'm not Craigaz, but I am wondering what you expect to find
> in your comparison.
>
> The SB2 is a $200 device (wired) with a display, case,
> computer and DAC.
>
> I would expect it to do no better than "OK" against a
> moderate expensive DAC. For example, the Benchmark DAC-1
> is a $1000 box with just the DAC and case. It is very good,
> I have one, but you can spend ten times that much
> for a "audiophile" DAC, maybe even more.
>
> If the SB2 is even "pretty good" as a DAC, I sure
> don't expect it to be as-good-as or better) than something like
> a Benchmark or Larvy or Crane -- which are all
> in the "about a grand" range.
>
> --
> Pat
> http://www.pfarrell.com/music/slimserver/slimsoftware.html
>
>
>

Michel Fombellida
2005-05-05, 07:15
Hi,

I have two SB2 (I also had the SB1) and I am using one of them to listen with headphones (Senn HD650) and I am using a Benchmark DAC1. With the SB1 the Benchmark was a must! Since I got the SB2 I did compare its headphone analog output to the headphone output of the Benchmark. The SB2 made serious progress as compared to the SB1, the Benchmark is still better but to be honest I am not sure I would have made the investment if I started directly with the SB2!

Michel

max.spicer
2005-05-05, 07:28
If it could come even close to something like the Benchmark
would inspire me to build a battery power supply [...]
I love reading these threads - I hardly understand a word of them! ;-) What is a battery power supply? I'm guessing that it's not a power supply that uses batteries and doesn't plug into the mains (except perhaps to recharge said batteries). That would just be far too simple!

windguy2
2005-05-05, 07:48
Correct, A 12volt 7amp gel cell battery and a simple circuit to convert
it to 5volts could power the SB2. A battery charger would also be
needed.

Mike

On May 5, 2005, at 8:28 AM, max.spicer wrote:

>
> windguy2 Wrote:
>> If it could come even close to something like the Benchmark
>> would inspire me to build a battery power supply [...]
> I love reading these threads - I hardly understand a word of them! ;-)
> What is a battery power supply? I'm guessing that it's not a power
> supply that uses batteries and doesn't plug into the mains (except
> perhaps to recharge said batteries). That would just be far too
> simple!
>
>
> --
> max.spicer
>
> The wild things roared their terrible roars and gnashed their terrible
> teeth
> and rolled their terrible eyes and showed their terrible claws
> but Max stepped into his private boat and waved good-bye
>

max.spicer
2005-05-05, 08:29
Correct, A 12volt 7amp gel cell battery and a simple circuit to convert
it to 5volts could power the SB2. A battery charger would also be
needed.
I realise that I'm probably going to regret asking this, but why? ;-)

windguy2
2005-05-05, 09:34
The SB2 uses an inexpensive power supply - usually improving the power
supply of audio equipment results in improved performance which usually
can be measured.
A battery power supply is a simple inexpensive way to avoid all the
issues of filtering the mains supply.


On May 5, 2005, at 9:29 AM, max.spicer wrote:

>
> windguy2 Wrote:
>> Correct, A 12volt 7amp gel cell battery and a simple circuit to
>> convert
>>
>> it to 5volts could power the SB2. A battery charger would also be
>> needed.
> I realise that I'm probably going to regret asking this, but why? ;-)
>
>
> --
> max.spicer
>
> The wild things roared their terrible roars and gnashed their terrible
> teeth
> and rolled their terrible eyes and showed their terrible claws
> but Max stepped into his private boat and waved good-bye
>

pfarrell
2005-05-05, 10:06
On Thu, 2005-05-05 at 08:01 -0600, windguy2 wrote:
> I haven't heard the Benchmark DAC1, but it is a class A stereophile
> product and highly rated. It includes volume, multiple digital inputs,
> variable analogue output, dedicated headphone outputs etc - remove all
> those options and maybe they could sell it as a standalone DAC for much
> much less.

Perhaps, perhaps not. The original Benchmark DAC-1 target was
serious project studios, and the flexibility is key.
I don't use the volume knob on mine, but I did have
to jumper it internally to select less gain on
its analog output as it was over-driving my Classe amp's
preamp section ( I run the SlimServer with volume control
locked wide open, the Benchmark jumpered wide open
and use the Classe's volume control)


> Standalone DAC's introduce other issues such as cable quality -

Part of being an audiophile is to obsess about nits, but
at the distances most people use between a Sqbx and DAC and
AMP, it can't be a major factor. "digital input" frequencies
are so low that any decent cable works.

Even the Toslink optical works well over limited distance.

On the output side, the cabling for the analog signal
can make a difference, but I sure can't tell one
$100 interconnect from another. I can tell a $100 interconnect
from a $3 one from radio shack

> The reason I am interested in the analogue output of the SB2 is that I
> believe it could sound very good because it is a relatively simple
> design. If it could come even close to something like the Benchmark
> would inspire me to build a battery power supply and look into other
> modifications.

I would expect it to sound very good, I didn't have any deep
problems with my SB1s, I bought the DAC-1 for my studio --
but I liked it so much the studio has to wait.

Just FYI, when I opened my DAC-1 I was boggled about the
size of the main torus. I assume it is for power supply
filtering, but I don't know for sure. It is about 3 inches
in diameter and at least an inch tall. And it weighs a ton.
Clearly much of the weight of the unit is in that one part.

Also, the Benchmark runs warm. This is a feature.
So don't forget to allow the heated air to escape.

In all this, the cost of the software (CDs) is
a much larger number than the cost of the audio gear.



--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

mkozlows
2005-05-05, 19:29
I have two SB2 (I also had the SB1) and I am using one of them to listen with headphones (Senn HD650) and I am using a Benchmark DAC1. With the SB1 the Benchmark was a must! Since I got the SB2 I did compare its headphone analog output to the headphone output of the Benchmark. The SB2 made serious progress as compared to the SB1, the Benchmark is still better but to be honest I am not sure I would have made the investment if I started directly with the SB2!


With the headphone output, I believe it. The SB1's headphone output is blatantly incapable of driving headphones like the HD650. I hooked my HD580 up to it once, shuddered, and never touched the headphone out again. Using the regular analog outs, though, the difference was much less pronounced. (By which I mean, "totally inaudible, so I returned the DAC-1," but YEMV.)

kefa
2005-05-07, 16:30
Theoretically, SB2 should be able to produce bit accurate information as it has no mechanical part. So, it should be able to replace the best transport.


also, how did you rip the files in the first place? I would be interested to know whether cd ripping software gets the data off a cd as accurately or even more accurately than a high-end transport.

I'm currently considering selling my high-end cd player and going the DAC route now that I have sb2+flac

pfarrell
2005-05-07, 17:19
On Sat, 2005-05-07 at 16:30 -0700, kefa wrote:


> also, how did you rip the files in the first place? I would be
> interested to know whether cd ripping software gets the data off a cd
> as accurately or even more accurately than a high-end transport.

I'm not ackcheng , but the basic answer is to read the data
several times, comparing a checksum until you get the same
data enough times to believe it.

If you are using Windows, EAC does a wonderful job.
EAC http://www.exactaudiocopy.de/

I'm a bit of a non-believer, in that I generally prefer
CDex http://cdexos.sourceforge.net/ as it is a lot faster and
not noticably less reliable.

For Linux, cdparanoia does what appears to be the same
things.

I have been reading the audiophile magazines for
ever, and have never seen any reason why
a high end transport should have any
improved ability to read a CD. There is not
a lot of magic reading either the red-book audio
or the direct extract data.

When I worked at a dot.com that ripped 40 thousand CDs,
we quickly found that different programs and different
computer drives got different bits from the same CD,
and that different copies of the same CD would yield
different bits unless you did the kinds of things that
EAC does, and use good CD drives. But good drives
are so cheap now that DVD burners are popular and cheap



--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

ackcheng
2005-05-09, 09:48
I use EAC!

sleepysurf
2005-05-10, 17:37
Great thread! Assuming I'm getting bit-perfect rips with EAC, and SB2 is now functioning as a pretty decent transport (especially for $300)... do I *really* need a ~$1000+ outboard DAC to achieve "audiophile" sound, or is there a no-frills DAC without all the bells and whistles (that I don't need) that would clearly improve upon the SB2 native DAC?? And what would be the pro's/con's of oversampling (? upsampling) from the SB2 bitstream?

Aylwin
2005-05-10, 22:38
The SB2 already comes with a no-frills DAC which is actually pretty good considering the price of the SB2 itself. In my opinion, whether you need an external DAC or not depends on your other components (preamp, amp, speakers, cables, etc.). I believe in the "a chain is only as strong as its weakest link" concept when it comes to audio systems. So, if the SB2 (with its internal DAC) is not currently the weakest link in your audio chain then adding an external DAC will make little, if any, difference.

As for the cost of DACs, there are quite a few decent ones under $1,000. There's the MSB LinkDAC III, Ack dAck, etc. (can't remember any more right now). There's even a DIY one here: http://www.diyparadiso.com/dac1.htm

Here's an interesting article on non-oversampling: http://www.sakurasystems.com/articles/Kusunoki.html

Patrick Dixon
2005-05-12, 01:06
I'm a bit of a non-believer, in that I generally prefer
CDex http://cdexos.sourceforge.net/ as it is a lot faster and
not noticably less reliable.I had a look at CDex, and it seems quite nice to use, but I couldn't figure out what I should set the Drive Offsets to. CDex requires Offsets in 'sectors' whereas EAC uses samples, and I'm not too sure how the two relate. CDex says that a 'sector' is 1/75th second which should be 588 x 2 = 1176 samples, which seems rather too course to be much use.

relen
2005-05-12, 05:50
I have been reading the audiophile magazines for ever, and have never seen any reason why a high end transport should have any improved ability to read a CD. There is not a lot of magic reading either the red-book audio or the direct extract data.

There are several reasons why CD-Audio transports can vary in their ability to read the disc. A 'traditional' CD player reads the disc in real time, and relies on the format's built-in error correction. If the disc read fails slightly, the player can accurately reconstruct (correct for) the missing data from the EC information. Next worse the player 'guesses' (interpolates) what the data might have been based on surrounding samples. This can adversely affect the sound. Worst of all the player mutes because it can't recover readable data.

A modern higher-end player may well use a DVD drive or other high-speed drive that can read the data at multiple speed. In this case, if there is a read error, the drive has several cracks at getting the actual data from the disc rather than guessing, without running out of buffer. This is a bit like the difference between running EAC in its full-blast bit-accurate mode as opposed to its basic hi-speed mode.

Then there is the question of jitter. Basic players can suffer a lot from this and the result is smearing of the stereo image amongst other things. A higher-end transport will use one or more FIFO buffers, super-stable clocks, good board design & grounding, and clean power supplies, to sort this out. This all costs money. Then you can go one step further and upsample to 88.2 kHz, which on the face of it is a waste of time, money and effort but turns out to work in ABX tests, if done well.

BTW, on the subject of DACs, I discovered (in ABX studio tests with Bob Clearmountain when I worked at Apogee) that I was not a fan of Benchmark's pro products, though I don't know any consumer gear of theirs. In the pro arena I would go for Apogee, Prism or dCS. In the consumer field, I am a great fan of Meridian, but I work there so I'm biased.

In the case of converters you get what you pay for /up to a point/. If you pay $500 per channel and/or go to Best Buy/Guitar Center, you still have a way to go before that point is reached.

--Richard E

pfarrell
2005-05-12, 07:53
On Thu, 2005-05-12 at 05:50 -0700, relen wrote:
> pfarrell Wrote:
> > I have been reading the audiophile magazines for ever, and have never
> > seen any reason why a high end transport should have any improved
> > ability to read a CD.
>
> There are several reasons why CD-Audio transports can vary in their
> ability to read the disc.

Right you are, I should have been more precise.
CDs have manufacturing errors, readers have errors, you get dirt,
fingerprints, etc.

Clearly doing stuff like EAC does can give you a higher probability
of getting the intended bits off the disk.


> This can adversely affect the sound. Worst of all
> the player mutes because it can't recover readable data.

Yes, the Red Book spec calls for so really hiddious error hiding
techniques.

The question I was trying to ask is: Why would there be a difference
between feeding a high end DAC with the output of the pure PCM
data from a computer over a megadollar audiophile transport,
such as the Meridian line you mention.

> Then there is the question of jitter. Basic players can suffer a lot
> from this

I also don't grok jitter in this context. I was trying to talk
about extracting the data from the CD. I don't see jitter here.
Perhaps I'm wrong.

Jitter in the signal stream has understandable cause,
altho all of the high end DACs claim to be immune or
at least resistant to it.


> BTW, on the subject of DACs, I discovered (in ABX studio tests with Bob
> Clearmountain when I worked at Apogee) that I was not a fan of
> Benchmark's pro products, though I don't know any consumer gear of
> theirs.

Can you please define what you mean by 'pro' here? or give model
numbers. In the studio world, "pro" usually means "sold a Guitar Center
to people who are wannabes"



--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

Deaf Cat
2005-05-16, 00:17
Interesting thread to read, good info.

Was just wondering if these "Audiophile" tests were carried out with the wired SB2 or with a wireless one ?

Sorry don't remember reading which was used, if it was mentioned, as I was rather intrested in the tests/DACs/EAC/sata setups etc.

Have not bought one yet but well on the way to getting my old pc set up as a server, and was thinking of the wireless SB2.
It would be nice to have a wireless set up but if the sound quality may drop across the air slightly, may well go for the wired option...........

Look forward to hearing any comments.

John Stimson
2005-05-16, 17:07
On Thursday my friend and I did some more direct testing, where one of us switched sources while the other listened.

Equipment: Squeezebox2 wired, MSB Nelson Link III DAC (standard power supply), Musical Fidelity A3.24, GE optical cable, Belden 1505 cable with Canare 75 Ohm RCA plugs.

The first comparison was with the MSB hooked up to the coaxial output and the Musical Fidelity hooked up to the optical output.

We both had a strong preference for the MSB. It seemed to have clearer transients and a deeper soundstage. It was slightly louder in the bass range as well, although that's not really a better/worse judgement, just an observation. The Musical Fidelity did have a sweet midrange and smooth sounding high treble, for a hint of "tube" sound.

Then we switched the cables. This time the difference was not as great. Our impression was that the Musical Fidelity improved significantly by switching to the coaxial cable, and the MSB lost little going to the optical cable. In any case, the difference in this comparison was less, but still distinguishable. Mike really liked how the Musical Fidelity DAC presented alto female voices, but still preferred the MSB for everything else. I didn't really notice much difference with the voices.

Overall result: we preferred the MSB, and think that the coaxial cable is the better interconnect.

I guess I'm going to have to build myself a high quality power supply for the MSB, and see if that makes any difference. I'm sure not shelling out $400 for the MSB Power Base...that's almost as much as I paid for the DAC itself!

shermoid
2005-05-17, 07:28
What storage device are you ordering? I am going to start a FLAC library and will need at least 500 GB to start. Preferably, I want a RAID 5 solution so I don't easily lose my FLACs.

hi there,

sorry for the late reply! i haven't checked all the messages for a while, and just saw yours.

i am using a fastora NAS-T4 device. the manufacturer is fastora (http://www.fastora.com). they make a NAS-T2 box, which holds 2 drives, and a NAS-T8 which holds 8 drives. all of them support RAID 0, 1, and 5. thae T4 and T8 also support hot spare, but for audio you probably don't need that.

i populated the NAS-T4 with 4 300G seagate drives (model st3300831art, parallel ata100, 7200rpm). these drives are very quiet, and come with a 5 year warranty.

i have been very pleased with the performance of the fastora device. i can rip, encode and listen to music all at the same time, without missing a beat! the nas box has 2 ethernet ports (1 10/100, and 1 gigabyte ethernet failover). i'm using the 10/100 port, which provides plenty of bandwidth. i found the fastora box online for $917, and the drives online at $176 each. if you're inetrested, just email me and i'll tell you where i got them from. i don't want to do a shameless plug for anyone on these forums! :-)

for a network diagram, please see my webpage (listed in the signature below). go to the "home built digital music server" section, and click on the link to the network diagram.

hope this helps! happy listening,
-sherman

Aylwin
2005-05-17, 19:20
Was just wondering if these "Audiophile" tests were carried out with the wired SB2 or with a wireless one ?

Have not bought one yet but well on the way to getting my old pc set up as a server, and was thinking of the wireless SB2.
It would be nice to have a wireless set up but if the sound quality may drop across the air slightly, may well go for the wired option...........I did my tests with a wireless SB2. Although I haven't actually compared the performance between wired and wireless, I doubt there will be any significantly noticeable difference in sound quality. Perhaps with a 802.11b connection there might be some problems on a heavily congested wlan.

Whether wired or wireless, go ahead and get an SB2. You won't regret it! :)


Overall result: we preferred the MSB, and think that the coaxial cable is the better interconnect.Nice comprehensive feedback, John. Good stuff! Obviously, as an MSB LinkDAC III owner (although not of the Nelson version) I'm also happy to hear your conclusion. :)

Fifer
2005-05-23, 02:34
for best sound quality it's important that your Squeezebox is set (via SlimServer) to fixed volume control and also to no limit bitrate.
I understand that the fixed volume setting for best sound quality applies to the analogue output, but not the digital.

relen
2005-05-23, 02:55
I understand that the fixed volume setting for best sound quality applies to the analogue output, but not the digital.

I would not have thought this was the case.

Assuming that the SB2 volume control is acting on the digital signal only, and is not either analog or an analog/digital combo, then essentially reducing the digital level fed to a) the digital outs and b) the analog outs means that you are using fewer bits to define the signal.

Imagine that you drop the digital level to a third. This means (very roughly) that instead of 24 bits per sample, equivalent to a dynamic range of around 144dB, you are using only 8 bits, or 48dB. As a result, low level signals will simply run out of bits and disappear below the noise (if the unit is properly dithered) or into quantization distortion (if it isn't).

In a perfectly-dithered digital system the noise floor is determined by the number of bits (if it's perfectly-dithered, the actual resolution is infinite, but this is, er, not easy to do: in a real system the signal will disappear into the noise at some point even with TPDF dither, the optimal form).

On the analog side, reducing the level fed to the DACs means that in addition to reducing the dynamic range as above, you will also degrade the signal to noise ratio.

Ideally with a digital system you want to run it as hot as you can without overloading. This ensures the best S/N ratio and the best dynamic range. At full output the SB2 digital outputs offer a perfect level for an external DAC operating at standard consumer S/PDIF levels.

In the case of the analog outs, you should really (in my view) only use the output level control in the SB2 if your external amp/speaker combination has no volume control (unusual) or if you are using headphones plugged straight into the box. Using the amp's volume control will reduce the noise with the signal; using the SB2's will reduce only the signal, in addition to the digital issues described above.

Hope this helps!

--Richard E

cliveb
2005-05-23, 07:04
Imagine that you drop the digital level to a third. This means (very roughly) that instead of 24 bits per sample, equivalent to a dynamic range of around 144dB, you are using only 8 bits, or 48dB.
I'm confused, because it's my understanding that you work for Meridian, who are renowned for their excellence in digital audio. So I must have misunderstood what you're trying to explain.

What exactly do you mean when you say "drop the level to a third"? If you mean you want to drop the voltage level of the resulting analogue signal to one third of the maximum (ie. about a 10dB reduction), then you don't lose anything like this number of bits: in fact you drop from 24 bits to about 22.4 bits, giving a dynamic range of about 134dB.

If you really do mean that you're going all the way down to 8 bits, then this represents a drop in the resulting analogue signal by a factor of over 65000. Suppose you set up your system so that a full-scale 24 bit signal plays at 110dBA (pretty loud). Then the signal resulting from dropping all the way to 8 bits will be about 14dBA; well below the background noise level of any domestic listening room. I don't think that quantisation noise is going to be a factor here.

Using the SB2's ability to adjust the SPDIF level when feeding a genuine 24-bit capable DAC strikes me as an entirely valid approach to volume adjustment. Isn't this precisely the way that digital volume controls on devices like the Meridian 518 work?

John Stimson
2005-05-23, 16:15
I think the primary potential for loss of fidelity is in the scaling and dithering required to adjust the volume digitally. If the samples were floating point numbers instead of integers, there would be no problem. With integers, somehow you are going to have to account for the fractional LSBs that you're rounding off. With a bad algorithm or limited processing power, you can lose fidelity. Maybe not much at first, but increasingly as you lower the volume.

If you lower the volume more than 48dB, then no matter how perfect your algorithm, you will start losing information that was present in the original 16-bit source material.

I too am baffled by an 8-bit signal being the result of "dropping the digital level to a third".

cliveb
2005-05-24, 00:57
If you lower the volume more than 48dB, then no matter how perfect your algorithm, you will start losing information that was present in the original 16-bit source material.
Yes, this is true. But in practice does it actually matter?

Let's say you're playing a 16-bit source with a peak level of 110dBA. At what level is the quantisation noise? 96dB down, ie. about 14dBA, which is *vastly* beneath the background noise level in any domestic listening environment, and is effectively inaudible.

Now drop the level by 48dB, ie. go down to 8-bit resolution. This takes the peak level down to 62dBA. And where is the quantisation noise now? 48dB down, ie. the same place as it was before (14dBA). This is still massively beneath the background noise level, and still effectively inaudible.

People make a big fuss about quantisation noise in digital systems, but in a domestic playback environment it's really not the bogey man everyone makes it out to be.

Fifer
2005-05-24, 02:15
I suspect that the last few posts suggest that using the digital volume control to adjust between approx. 95% and 100% of full volume to balance sound level between different albums isn't really going to make a significant difference to sound quality?

relen
2005-05-24, 14:39
Using the SB2's ability to adjust the SPDIF level when feeding a genuine 24-bit capable DAC strikes me as an entirely valid approach to volume adjustment. Isn't this precisely the way that digital volume controls on devices like the Meridian 518 work?

All I can say is that sometimes I write a load of sloppy rubbish. Right in principle, but indeed maybe you can't hear it. I must learn not to write things last thing at night. Apologies.

The 518 is before my time. However as far as I am aware in most current digital products we do not use a purely digital level control: it's a hybrid analog/digital control in which the digital output is scaled in a series of steps with analog control 'between' the steps. This is because if you did the control entirely digitally you'd lose resolution.

In addition I was assuming that you would be using a digital output control not to vary the level (as in a volume control per se) but to provide gain-structure matching between the digital device and the amplifier or whatever. If you had the digital output turned down to match a high-gain analog input for example, so that the final audio output was fairly respectable then sure you'd hear quantization distortion, noise etc.

In such situations I would rather run the digital side at full bore - ie minimal headroom, maximum twiddling of bits - and turn down the /analog/ gain at the input to the amplifier, thus reducing the noise while maintaining the full dynamic range on the digital side.

Yes, you can argue that a 24-bit system ought to have 144dB dynamic range and if you turn that down on the analogue side quiet signals will probably be swamped by analogue input noise, but once again I'm too tired to be sensible and this is probably rubbish too.

--R

seanadams
2005-05-24, 15:55
I understand that the fixed volume setting for best sound quality applies to the analogue output, but not the digital.

Just to confuse this further:

**Squeezebox1** had separate digital and analog volume control capabilities in hardware - this just happened to be included in its integrated DSP chip. The feature was not used initially - we just always used the digital volume control, because that was the only way to make the volume control work both sets of outputs together, which is what most users wanted. We added the "fixed digital level" option later, which changed the analog outputs to use the analog volume control.

**Squeezebox2** does NOT have attenuation capability AFTER the DAC, although there is an attenuation feature IN the DAC (digital, presumably) which we're not currently using - see related thread and bug entry: http://forums.slimdevices.com/showthread.php?t=14382


So, the "fixed digital level" feature as respects analog vs digital volume control really only applies to Squeezebox1. In Squeezebox1 it had a very real improvement in noise floor, especially if you were using the headphone output.

In Squeezebox2 we have full 24 bits through to the s/pdif and the DAC, so instead what this feature does is just not apply volume control on s/pdif. It doesn't actually change the mechanism of volume control for the analog outputs.

Fifer
2005-05-25, 00:22
Just to confuse this further:

**Squeezebox1** had separate digital and analog volume control capabilities in hardware - this just happened to be included in its integrated DSP chip. The feature was not used initially - we just always used the digital volume control, because that was the only way to make the volume control work both sets of outputs together, which is what most users wanted. We added the "fixed digital level" option later, which changed the analog outputs to use the analog volume control.
Would it have been possible to have the firmware respond to the volume buttons by simultaneously adjusting the digital and analogue volume controls, providing the optimum solution for both outputs, or are the DSP volume controls effectively in series?

cliveb
2005-05-25, 01:30
**Squeezebox2** does NOT have attenuation capability AFTER the DAC, although there is an attenuation feature IN the DAC (digital, presumably) which we're not currently using .....

In Squeezebox2 we have full 24 bits through to the s/pdif and the DAC, so instead what this feature does is just not apply volume control on s/pdif. It doesn't actually change the mechanism of volume control for the analog outputs.
Just to make sure I understand correctly. You're saying that the way the *analogue* output volume control works is actually that you apply arithmetic attenuation to the *digital* signal before it goes to the DAC, right?

What this means in practice is that, if at max volume you're feeding 24 bit signals to the DAC, then at -6dB, you're actually using 23 bits of the possible resolution; at -12dB we're down to 22 bits, and so on. That's fine by me; I have no philosophical problems with this (as you can probably deduce from my earlier posts in this thread), but I suspect it's going to worry a few others around here.

seanadams
2005-05-25, 08:13
Would it have been possible to have the firmware respond to the volume buttons by simultaneously adjusting the digital and analogue volume controls, providing the optimum solution for both outputs, or are the DSP volume controls effectively in series?

Right, series, hence the need for the setting.

seanadams
2005-05-25, 08:21
Just to make sure I understand correctly. You're saying that the way the *analogue* output volume control works is actually that you apply arithmetic attenuation to the *digital* signal before it goes to the DAC, right?

What this means in practice is that, if at max volume you're feeding 24 bit signals to the DAC, then at -6dB, you're actually using 23 bits of the possible resolution; at -12dB we're down to 22 bits, and so on. That's fine by me; I have no philosophical problems with this (as you can probably deduce from my earlier posts in this thread), but I suspect it's going to worry a few others around here.

Well, you and I understand the math, so of course we wouldn't be concerned. However, if one objected on a philosophical basis then he could just use his receiver's volume setting, just like you'd do with a CD player. :)

SteveC
2005-05-26, 01:06
* earthbased shaped the electrons to say...

>RAID 5 uses at minimum 3 drives to stripe data and parity info across
>them. If one drive fails, the lost data can be re-constructed in
>real-time until the drive is replaced. I just read about the
>TERASTATION; looks like that is my solution for my FLAC files.

The Terastation has abysmal throughput. I suggest you look elsewhere... Please could you specify more exactly what you meant by this comment. I'm led to expect from tests about 1.3 MByte/s throughput when acting as a server and I wonder if this is what you mean by "abysmal throughput"?

rich spengel
2005-06-03, 10:58
hi there,

sorry for the late reply! i haven't checked all the messages for a while, and just saw yours.

i am using a fastora NAS-T4 device. the manufacturer is fastora (http://www.fastora.com). they make a NAS-T2 box, which holds 2 drives, and a NAS-T8 which holds 8 drives. all of them support RAID 0, 1, and 5. thae T4 and T8 also support hot spare, but for audio you probably don't need that.

i populated the NAS-T4 with 4 300G seagate drives (model st3300831art, parallel ata100, 7200rpm). these drives are very quiet, and come with a 5 year warranty.

i have been very pleased with the performance of the fastora device. i can rip, encode and listen to music all at the same time, without missing a beat! the nas box has 2 ethernet ports (1 10/100, and 1 gigabyte ethernet failover). i'm using the 10/100 port, which provides plenty of bandwidth. i found the fastora box online for $917, and the drives online at $176 each. if you're inetrested, just email me and i'll tell you where i got them from. i don't want to do a shameless plug for anyone on these forums! :-)

for a network diagram, please see my webpage (listed in the signature below). go to the "home built digital music server" section, and click on the link to the network diagram.

hope this helps! happy listening,
-sherman


I have some thoughts on music storage. I am ripping my collection to FLAC at minimum compression, and it is clear that
about 1000 albums will fit on my 300GB ($150) hard drive. You would use even less space with more compression. It is also clear that it takes considerable time to do all that ripping and album art searching. By the time you get through the first 1000 discs (groan) you will probably be able to buy another 300 GB drive for about 75 cents or thereabouts. This sounds pretty economical. I also can't figure why you would want to break the bank with a RAID array. I bought a 300GB external hard drive ($200) for backup and keep it in a safe place. Offsite is best. This is cheap, fast and convenient. When my internal music drive goes toes-up, I can buy a new one (for 75 cents?) and reload it in short order. Can anyone shoot any holes in my theories?

pfarrell
2005-06-03, 11:15
On Fri, 2005-06-03 at 10:58 -0700, rich spengel wrote:
>
> I have some thoughts on music storage. I am ripping my collection to
> FLAC at minimum compression, and it is clear that
> about 1000 albums will fit on my 300GB ($150) hard drive.

A minor nit, the flac compression control is for controlling
how long the encoded tries to squash the bits. Higher
setting take lots longer and only yield a modest amount of
additional compression.

Its all "flac compression" and easy to expand.

> Offsite is best. This is cheap, fast and convenient. When my internal
> music drive goes toes-up, I can buy a new one (for 75 cents?) and reload
> it in short order. Can anyone shoot any holes in my theories?

I think your approach is fine. I dispense with the backup
disk, and consider my 800+ CDs as backup.
But I would rather not have to reextract and recompress them



--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

Robin Bowes
2005-06-03, 12:54
Pat Farrell wrote:
> I think your approach is fine. I dispense with the backup
> disk, and consider my 800+ CDs as backup.
> But I would rather not have to reextract and recompress them

To right. The thought of all those hundreds of hours... ugh! $200 for a
back up disk sounds cheap at twice the price.

Personally, I've got 6 x 250GB drives in a RAID5 array (4+1 + spare)
giving me a 974566400 byte drive (929.42 GiB 997.96 GB).

Now, backing that up is a bit of a pain... :)

R.
--
http://robinbowes.com

Robin Bowes
2005-06-03, 13:22
Robin Bowes wrote:
> To right. The thought of all those hundreds of hours... ugh! $200 for a

Ooops, call me pedantic but I did of course mean "Too right".

R.
--
http://robinbowes.com

kronos
2005-06-03, 15:05
Hola ! fantastic brothers ( and sisters ) of the squeezebox community...

=)

...been reading AVIDLY and i'm wondering about TWO points :

1 - can i set-up a network drive to be used with the squeezebox 2 WITHOUT a PC ? ( i would have two plugs on the drive ethernet port to connect the PC for data transfer, but i wouldn't like to hear the HUMMING of the PC while i listen to my stored music, hence the need to turn the PC off but still access the HD )

2 - question to the gentleman who performed the ACCUPHASE CD/DAC test; here's another vote to ask for you ( or anyone else with an audiophile grade DAC ) to give us your impressions on the ANALOG output of the squeezebox 2 compared to your hi-end hi-fi set-up

...can anyone help on these two points ?

THANKS A BUNCH !
looking forward to your replies,
cordially,
KRONOS

earthbased
2005-06-03, 17:16
Hola ! fantastic brothers ( and sisters ) of the squeezebox community...

=)

...been reading AVIDLY and i'm wondering about TWO points :

1 - can i set-up a network drive to be used with the squeezebox 2 WITHOUT a PC ? ( i would have two plugs on the drive ethernet port to connect the PC for data transfer, but i wouldn't like to hear the HUMMING of the PC while i listen to my stored music, hence the need to turn the PC off but still access the HD )

2 - question to the gentleman who performed the ACCUPHASE CD/DAC test; here's another vote to ask for you ( or anyone else with an audiophile grade DAC ) to give us your impressions on the ANALOG output of the squeezebox 2 compared to your hi-end hi-fi set-up

...can anyone help on these two points ?

THANKS A BUNCH !
looking forward to your replies,
cordially,
KRONOS

Get a Kuro Box. It uses 17W power and is very quiet.

Dan

kronos
2005-06-03, 17:43
Get a Kuro Box. It uses 17W power and is very quiet.

Dan

thanks for the tip Dan, do i take your reply as a NO to my 1 - question ?

=(

EDIT - just checked the web for the KURO BOX, and found out the NSLU2, as well the Netgear WGT634U.

...in particular, the NETGEAR would suit me just fine; can i use it or the NSLU2 instead of the KURO BOX, or do they STILL need a PC to run the software to link the SB2 to the HD ? ( it remains that this question stands ONLY if i can't access any HD from the SB2 directly that is... )

pfarrell
2005-06-03, 18:01
On Fri, 2005-06-03 at 17:43 -0700, kronos wrote:
> earthbased Wrote:
> > Get a Kuro Box. It uses 17W power and is very quiet.
> thanks for the tip Dan, do i take your reply as a NO to my 1 - question

I'm not Dan, but part of the confusion may be that you asked if you
need "a PC" and the answer is either "no, a Kuro box will work" or

"define what is a PC" since what you really need is a computer running
a supported operating system. The box doesn't need a powerful CPU
and nearly any modern OS is supported. Win XP, 2K, Mac OS9 & 10, Any
Linux, etc.

People talk about running the SlimServer on Tivos.
Or on NAS boxes, which are supposed to only have disks,
but actually have a CPU and linux in addition to the disks.

The SlimServer must run on a computer. Not much of a computer, I bet
someone has hacked a Xbox to run it.

I ran mine for over a year on a free PC that a buddy gave me, stuck
down in the basement so I didn;'t have to hear its fans


--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

earthbased
2005-06-03, 18:02
thanks for the tip Dan, do i take your reply as a NO to my 1 - question ?

=(

EDIT - just checked the web for the KURO BOX, and found out the NSLU2, as well the Netgear WGT634U.

...in particular, the NETGEAR would suit me just fine; can i use it or the NSLU2 instead of the KURO BOX, or do they STILL need a PC to run the software to link the SB2 to the HD ? ( it remains that this question stands ONLY if i can't access any HD from the SB2 directly that is... )

You need something that can run SlimServer; the Kuro Box can. The Kuro Box is basically an open source version of the Buffalo LinkStation. So you can load whatever linux programs on it you like.

kronos
2005-06-03, 18:50
THX guys, now i get it; will report your replies to the appropriate thread i opened in the "beginners" section of the board, and stick to question number 2 of my post here ( about SB2 DAC quality comparisons ) to avoid mix-ups.

THANKS !=)

Aylwin
2005-06-05, 07:15
Although I don't own a high-end DAC, I'll offer my opinions on your 2nd question. I have an MSB LinkDAC III which I think is very good for the price. I consider it entry level audiophile along with the rest of my stereo setup.

To my ears, the analog outputs of the SB2 can't compare to its digital output + external DAC. To me, the difference is very significant and doesn't even require blind testing. In my opinion, for the SB2 to be in a high end setup, an external DAC is a must. Others will probably disagree but this subjective anyway. Everyone has different equipment, listening environments, preferences, and ears.

Still, I think the SB2's internal DAC and analog outputs are very good considering the price of the whole unit. I have my SB2 connected via analog to an integrated amp and I think it works quite well.

What amazes me though is how well the SB2 works as a digital transport. To me, there's no noticeable difference between the SB2 (with the digital output bypassing volume control) and my CD changer when both are connected to the external DAC.

kronos
2005-06-05, 20:28
thanks AYLWIN, that's exactly the kind of replies i'm looking forward to reading about my question.

=)

Mike Hanson
2005-06-06, 02:32
To my ears, the analog outputs of the SB2 can't compare to its digital output + external DAC. To me, the difference is very significant and doesn't even require blind testing. In my opinion, for the SB2 to be in a high end setup, an external DAC is a must. Others will probably disagree but this subjective anyway. Everyone has different equipment, listening environments, preferences, and ears.[Bold Added]
I hope no one jumps to the conclusion that the SB2's internal DAC is unacceptable. Although my office system is far less impressive than my main system in my listening room, it's still arguably a "high end setup" (Naim NAC102 pre-amp, MyNAPSC and Naim SNAPS2 (dual-railed) power supplies, Naim NAP110 power-amp, and Royd Merlin speakers). I listen in a "nearfield" configuration, and it's very revealing!

My standards are quite demanding, yet I've been very impressed with the SB2's internal DAC. In fact, some of the external DACs that I used were no better. One was the DAC in my Roland VS-880 home studio, another was the M-Audio Delta 410 card in my studio PC, and the best was the the Scott Nixon Chibi Saru. Only the Chibi Saru was able to exceed the SB2, but that required an impressive external power supply for the Chibi Saru. With a lesser supply, it was below the SB2. The one DAC that I've tried that is very obviously better is the Benchmark DAC1.

The moral of the story here is don't assume that you MUST have an external DAC to appreciate the SB2 in an "audiophile" system. You might save yourself a bit of money.

BTW, the SB1's internal DAC sounds like crap! Nuff said!

-=> Mike Hanson <=-

Aylwin
2005-06-06, 03:29
I hope no one jumps to the conclusion that the SB2's internal DAC is unacceptable.
I agree. My opinion is mearly based on my own experience with the SB2 on my listening room system. On my other system it is more than acceptable. And I'm sure it also is on many many other systems.


The moral of the story here is don't assume that you MUST have an external DAC to appreciate the SB2 in an "audiophile" system. You might save yourself a bit of money.
I'll agree but... the above depends on some subjective variables.

First, each person's definition of an "audiophile system" may vary.

Second, my definition of external DAC is a dedicated box in which the sole purpose is to convert digital input (coming from a source CD) to analog line level output. So internal DACs of receivers, sound cards or any other devices with more than a simple DAC function don't count.

And finally, kronos did ask "to give us your impressions on the ANALOG output of the squeezebox 2 compared to your hi-end hi-fi set-up". I can't possibly imagine how the SB2's internal DAC and analog section can be expected to perform at the level required in a hi-end system. Even in my non hi-end system, the difference is obvious.

Therefore, I would say that an external DAC is, in fact, a MUST to appreciate the SB2 in a hi-end audiophile system. If it's not a hi-end system then perhaps not. It still depends on the system though (like in my case).

But like I said previously, this is all subjective. There is no right or wrong. Just varying opinions based on varying experiences.

Mike Hanson
2005-06-06, 05:46
I'll agree but... the above depends on some subjective variables.

First, each person's definition of an "audiophile system" may vary.
Of course! However, I think most would consider my office amplification and speakers (which would have retailed for well over $5K when new) as an "audiophile system". Sure, my downstairs system is better, and it considering it cost 10 times as much, it certainly should be. Regardless, either system was easily able to resolve the difference between the DACs that I tested.


Second, my definition of external DAC is a dedicated box in which the sole purpose is to convert digital input (coming from a source CD) to analog line level output. So internal DACs of receivers, sound cards or any other devices with more than a simple DAC function don't count.
I think you're being a bit pedantic. Even if it's not in a single-purpose box, it's still a separate DAC, with its own performance traits. For example, the DAC in my Roland VS-880 was far better than the SB1's internal module, and I was happy to use it for a while. Ignoring it just because it's not a single-purpose device doesn't make much sense.


And finally, kronos did ask "to give us your impressions on the ANALOG output of the squeezebox 2 compared to your hi-end hi-fi set-up". I can't possibly imagine how the SB2's internal DAC and analog section can be expected to perform at the level required in a hi-end system. Even in my non hi-end system, the difference is obvious.
Why must the SB2's internal DAC be discounted, just because it's included in the box? And as far as hearing differences, almost any change in a system will result in an audible difference. As to whether it’s good/bad, or sufficiently worthwhile for the investment is another matter altogether.


Therefore, I would say that an external DAC is, in fact, a MUST to appreciate the SB2 in a hi-end audiophile system. If it's not a hi-end system then perhaps not. It still depends on the system though (like in my case).

But like I said previously, this is all subjective. There is no right or wrong. Just varying opinions based on varying experiences.
Exactly! The point I was trying to make was that not everyone would determine that an external DAC is a "MUST", and that you should begin with the understanding that the internal DAC in the SB2 is really quite good.

Ultimately, finding an external DAC with significantly better performance was more of a challenge than I originally expected, so everyone should go into this with an open mind.

-=> Mike Hanson <=-

Aylwin
2005-06-06, 07:39
I think most would consider my office amplification and speakers (which would have retailed for well over $5K when new) as an "audiophile system".

I'm just saying that, in general, definitions may vary. This has nothing to do with your system and and nothing to do with cost.


I think you're being a bit pedantic. Even if it's not in a single-purpose box, it's still a separate DAC, with its own performance traits. For example, the DAC in my Roland VS-880 was far better than the SB1's internal module, and I was happy to use it for a while. Ignoring it just because it's not a single-purpose device doesn't make much sense.

Well, it makes sense to me and it's down to definitions. Maybe I AM being pedantic but to me, an audiophile system consists of: 2 front speakers, speaker cables, power amp + pre amp (or integrated), interconnects and a source. For our purposes, that source is PCM (from a CD player or via the SB2). So, if I were to consider whether or not to add an external DAC to my existing audiophile setup then it would naturally be a dedicated box. What other functionality would I need to add? To my understanding, that was the point of the original question.

Obviously, if there are other components in the existing system that also have DACs (like a receiver or sound card) then a comparison can easily be made. One can then judge which of their components has the best internal DAC. That may very well be the SB2. Still, the SB2 won't beat a good external DAC (or should I say, dedicated DAC?) as you yourself have noticed with your Benchmark.



The point I was trying to make was that not everyone would determine that an external DAC is a "MUST", and that you should begin with the understanding that the internal DAC in the SB2 is really quite good.

No arguments there. My point was just referring to the original question where I still feel that an external DAC is a must in a hi-end audiophile system. I don't think that necessarily conflicts with your statement above.


Ultimately, finding an external DAC with significantly better performance was more of a challenge than I originally expected...

By my definition of "external DAC" where I only consider dedicated boxes, it's not a challenge at all. Again, you may say I'm being pedantic but the definition matters to me. To name a few external DACs that I would consider:

MSB LinkDACIII or higher (includes Nelson, Gold and Platinum)
Bel Canto DAC
California Labs Alpha or Sigme DAC
Musical Fidelity A234 (and maybe even X-DAC)
Audio Note DAC 1.1 or higher
Ack DAC
Perpetual Technologies P-3A
EVS Millenium DAC
plus, the Scott Nixon (with good power supply)
and Benchmark DAC1 you've already mentioned.

Obviously, receivers, pc sound cards and the like don't count. Why would I add one of those to a perfectly working audio system?

I think we're arguing two different things. I don't disagree with any of your comments. I completely agree that the SB2's analog outputs are very good indeed. However, do you disagree that an external DAC (like the one's I've mentioned above) is a must for the SB2 to be in a hi-end audiophile system? Okay, if "must" is a bit strong, how about we say that an external DAC provides a considerable noticeable improvement?

Mike Hanson
2005-06-06, 12:02
do you disagree that an external DAC (like the one's I've mentioned above) is a must for the SB2 to be in a hi-end audiophile system? Okay, if "must" is a bit strong, how about we say that an external DAC provides a considerable noticeable improvement?
Yes, a dedicated, external DAC can be superior to the SB2's internal DAC. However, this isn't a given: I've already observed that the Scott Nixon Chibi Saru is inferior to the lone SB2, until you add a good power supply. Then it does surpass it by a bit, but not a lot. IMO, the SB2 is that good!

I started down this road before the SB2 was released. My original, tentative plan was to use the SB1 with the Scott Nixon DAC in my main system, and then to decide what to do in my secondary system. Then the SB2 was released and I received the Scott Nixon DAC, and I realised it wasn't significantly better than the SB2 (although it certainly surpassed the SB1). So I went out and bought a Benchmark DAC1, which is really, really good.

I want the extra buffer of the SB2 (and a few of the other features) in my listening room, working with the Benchmark DAC1. That leaves the SB1 and Scott Nixon DAC in my office. If, however, I had a spare SB2, I would happily use it without an external DAC in my office. IOW, my high expectations are nominally satisfied with the internal DAC of the SB2 (although I certainly appreciate the marginally superior performance that I get from the Scott Nixon DAC).

I should interject something here. You claim to be able to hear differences between transports, while I can’t honestly admit that I can do the same. Perhaps they seem different to me, and perhaps I just want them to. (I certainly hear the difference between DACs!) If you really can discern the differences between transports, then perhaps your ears are more golden than mine, and the money that I’ve spent on my fancy-dancy “audiophile systems” is all for naught, when I could be completely happy with a P.O.S. Bose system. <sigh>

I think we understand each other quite well at this point, and we’re merely arguing the concepts of “want” vs. “need”, and “optional” vs. “a must”.

-=> Mike Hanson <=-
The Sarcastic Bastard

Aylwin
2005-06-06, 13:07
I think we understand each other quite well at this point, and we’re merely arguing the concepts of “want” vs. “need”, and “optional” vs. “a must”.
Agreed! And thanks for the background story. It's always better to know that kind of stuff.

As for my being able to tell the difference between transports, I can't say categorically that I can. I believe I heard a difference between my CD changer and the SB2 when I initially tested it. Who knows? Maybe I imagined it.

However, I've since discovered that you can bypass volume control on the digital output. Actually, I learned about that in this thread. Anyway, now I can't tell the difference.

Mike Hanson
2005-06-06, 13:19
Anyway, now I can't tell the difference.
I've developed the belief that, while in the digital domain, things need to be "good enough". Beyond that point, it's all essentially the same. Less than that, and you're getting all sorts of data problems, and the overall performance suffers.

This explains why different transports, assuming they're all "good enough", won't sound appreciably different. However, DACs also work in the analog domain, and that's where the real differences can be heard.

-=> Mike Hanson <=-

seanadams
2005-06-07, 22:49
This explains why different transports, assuming they're all "good enough", won't sound appreciably different.

Agreed - once it's in digital land, it's only a matter of having no errors (jitter doesn't count BTW; that's really an analog phenomenon).

However, the thing about an opto/mechanical (CD) transport is that you have to deal with how well the, uh, transport itself is working - and that's a real-world error-prone process involving light, motors, and quite fragile media. I have several real-life, perfectly reproducible cases where a slightly scratched CD plays fine in one player, and with skips/clicks in another. On a CD with even the most utterly microsocopic imperfections (even a brand new one), you'll find one transport plays it with more errors than another. Impercipble to the ear, maybe, (a single bad sample just gets interpolated) but it's not digital perfection.

SB2 does have quite an "unfair" advantage in that our "transport" simply doesn't have to deal with frequent read errors. As long as the hard drive is functioning and the network is fast enough, it just works.

There is a simple but time-consuming empirical test you could do (maybe I'll try this if nobody else has), which is to simply measure the bit error rate of various CD transports. Then you want to compare the output from a good ripper, say EAC, which I expect would outperform any audio CD player. The reason I say that is because a ripper is not encumbered by real-time constraints, and can take as long as it likes to retry a particular read attempt until it gets the best possible data.

Aylwin
2005-06-08, 00:08
Agreed - once it's in digital land, it's only a matter of having no errors (jitter doesn't count BTW; that's really an analog phenomenon).Ummm... sorry, I beg to disagree. Jitter is very digital. Okay, maybe we could argue that it's analog but the point is that it primarily affects the digital domain. Being lazy, here's a definition I found on the internet:

Jitter is the deviation in or displacement of some aspect of the pulses in a high-frequency digital signal. As the name suggests, jitter can be thought of as shaky pulses. The deviation can be in terms of amplitude, phase timing, or the width of the signal pulse. Another definition is that it is "the period frequency displacement of the signal from its ideal location." Among the causes of jitter are electromagnetic interference (EMI) and crosstalk with other signals. Jitter can cause a display monitor to flicker; affect the ability of the processor in a personal computer to perform as intended; introduce clicks or other undesired effects in audio signals, and loss of transmitted data between network devices. The amount of allowable jitter depends greatly on the application.

I would be willing to accept Mike's "good enough" but I have trouble with "it's only a matter of having no errors". However, I think one key point from the definition above is, "The amount of allowable jitter depends greatly on the application".

I come from the telecoms world where jitter can be a real headache in digital transmission networks. It probably is less of a factor for audiophile applications but how much less I honestly don't know. Still, for a real-time application where digital transmission is involved I would assume that synchronization and clock recovery are also important. Please correct me if this assumption is wrong.

mwphoto
2005-06-08, 00:38
Aylwin wrote:

> I would be willing to accept Mike's -"good enough"- but I have trouble
> with -"it's only a matter of having no errors"-. However, I think one
> key point from the definition above is, -"The amount of allowable
> jitter depends greatly on the application"-.

I agree, and possibly the confusion arises because there are two distinct
applications in place when using an SB2. I think the issue here is more the
management or errors. Protocols like TCP/IP (which are used for PC <-> SB2)
have inbuilt checks to identify errors (caused by jitter). In this case they
can simply be requested again and corrected. This means the SB2 is always
processing from a perfect copy of the wav/flac/mp3 sent by the PC. For PC
networks errors are a normal part of operation, but no-one notices because
the built in protocols correct the errors before any downstream processing
happens.

In a pure audio stream (such as you get from a CD transport) there is no
error correction or buffering so if jitter causes an error there is no way
to identify it unless it causes a nasty spike and no time to request a
resend to perfectly correct it. In this case interpolation has to be used
and this degrades audio quality.

So in summary, the digital (network) link between the PC and SB2 and the
digital link from SB2 to DAC both suffer from jitter, however in the PC/SB2
link the network speed and protocols allow errors to be identified and
corrected. The approach taken for identifying and correcting errors in the
SB2/DAC stream means that errors reduce audio quality.

As regards clock synching and so forth my old ARCAM transport had a separate
clock signal, I wonder if this is something that could be considered for the
SB3? Actually it might even be possible for the SB2 if the firmware would
allow the 2 digital outputs to be used for different purposes (data and
clock).

Malcolm



> -----Original Message-----
> From: audiophiles-bounces (AT) lists (DOT) slimdevices.com
> [mailto:audiophiles-bounces (AT) lists (DOT) slimdevices.com]On Behalf Of Aylwin
> Sent: 08 June 2005 08:09
> To: audiophiles (AT) lists (DOT) slimdevices.com
> Subject: [SlimDevices: Audiophiles] Re: "SB2" and "Audiophile" go
> together?
>
>
>
> seanadams Wrote:
> > Agreed - once it's in digital land, it's only a matter of having no
> > errors (jitter doesn't count BTW; that's really an analog
> phenomenon).Ummm... sorry, I beg to disagree. Jitter is *very*
> digital. Okay,
> maybe we could argue that it's analog but the point is that it
> primarily affects the digital domain. Being lazy, here's a definition I
> found on the internet:
>
> -Jitter is the deviation in or displacement of some aspect of the
> pulses in a high-frequency digital signal. As the name suggests, jitter
> can be thought of as shaky pulses. The deviation can be in terms of
> amplitude, phase timing, or the width of the signal pulse. Another
> definition is that it is "the period frequency displacement of the
> signal from its ideal location." Among the causes of jitter are
> electromagnetic interference (EMI) and crosstalk with other signals.
> Jitter can cause a display monitor to flicker; affect the ability of
> the processor in a personal computer to perform as intended; introduce
> clicks or other undesired effects in audio signals, and loss of
> transmitted data between network devices. The amount of allowable
> jitter depends greatly on the application.-
>
> I would be willing to accept Mike's -"good enough"- but I have trouble
> with -"it's only a matter of having no errors"-. However, I think one
> key point from the definition above is, -"The amount of allowable
> jitter depends greatly on the application"-.
>
> I come from the telecoms world where jitter can be a real headache in
> digital transmission networks. It probably is less of a factor for
> audiophile applications but how much less I honestly don't know.
> Still, for a real-time application where digital transmission is
> involved I would assume that synchronization and clock recovery are
> also important. Please correct me if this assumption is wrong.
>
>
> --
> Aylwin
>

Robin Bowes
2005-06-08, 15:22
Malcolm Wotton wrote:
> So in summary, the digital (network) link between the PC and SB2 and the
> digital link from SB2 to DAC both suffer from jitter, however in the PC/SB2
> link the network speed and protocols allow errors to be identified and
> corrected. The approach taken for identifying and correcting errors in the
> SB2/DAC stream means that errors reduce audio quality.

No, not quite. Jitter is not an issue in the PC->SB2 link. You can
pretty much do what you like in the digital domain because bits are
bits. It's only when you start converting them back into analogue domain
that the timing information becomes critical and jitter becomes an issue.

R.
--
http://robinbowes.com

Andrew L. Weekes
2005-06-08, 15:44
However, the thing about an opto/mechanical (CD) transport is that you have to deal with how well the, uh, transport itself is working - and that's a real-world error-prone process involving light, motors, and quite fragile media. I have several real-life, perfectly reproducible cases where a slightly scratched CD plays fine in one player, and with skips/clicks in another. On a CD with even the most utterly microsocopic imperfections (even a brand new one), you'll find one transport plays it with more errors than another. Impercipble to the ear, maybe, (a single bad sample just gets interpolated) but it's not digital perfection.

It's often salient to remember that the signal from the CD player pickup (mechanism) isn't digital at all, it's a high-frequency RF signal, with plenty of opportunity for it to get messed up before we even get to processing it!

Anyway, to try and understand and visualise jitter better, this little FAQ may help: -

http://www.pinkfishmedia.net/forum/showthread.php?s=&threadid=10480

Jitter only matters, in audio terms, at one point and one point only, the point of domain conversion (i.e. A to D or D to A conversion - OK that's two places ;) ). In extreme cases it could corrupt data on a digital link, but that's not the same as the actual analogue errors introduced at the conversion stage.

Andy.

Robin Bowes
2005-06-08, 15:54
Andrew L.Weekes wrote:
> -However, the thing about an opto/mechanical (CD) transport is that you
> have to deal with how well the, uh, transport itself is working - and
> that's a real-world error-prone process involving light, motors, and
> quite fragile media. I have several real-life, perfectly reproducible
> cases where a slightly scratched CD plays fine in one player, and with
> skips/clicks in another. On a CD with even the most utterly
> microsocopic imperfections (even a brand new one), you'll find one
> transport plays it with more errors than another. Impercipble to the
> ear, maybe, (a single bad sample just gets interpolated) but it's not
> digital perfection.-
>
> It's often salient to remember that the signal from the CD player
> pickup (mechanism) isn't digital at all, it's a high-frequency RF
> signal, with plenty of opportunity for it to get messed up before we
> even get to processing it!
>
> Anyway, to try and understand and visualise jitter better, this little
> FAQ may help: -
>
> http://www.pinkfishmedia.net/forum/showthread.php?s=&threadid=10480

All good stuff.

Just to clarify, I was talking about the Squeezebox not CD players.

R.

--
http://robinbowes.com