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WSLam
2005-06-21, 21:48
I am so happy with the SB2 (replacing slowly, my Linn CD12) that I really hope SD will build an 'audiophile' version of the SB.

Here are a list of features I could think of! Hope you guys can all pitch in:

- No Internal DAC. Save the cost, and spend it on elsewhere
- AES Digital Out (That would make my day!)
- No Volume control, the simpler the circuit, the better
- WBT or Neutrik connectors
- Make it heavier! =) audio nuts are all for heavy equipment! (otherwise, the AES cable is gonna make the SB2 'move')
- A even better, higher resolution display.
- more 'solid' feel remote control

Anyone else?

ws

WSLam
2005-06-21, 21:51
Oh one more...
Remote Display... maybe something like the Sonos controller. =)
Audiophiles will pay!

pfarrell
2005-06-21, 22:10
On Tue, 2005-06-21 at 21:48 -0700, WSLam wrote:

> - No Internal DAC. Save the cost, and spend it on elsewhere
> Anyone else?

I am not an IC engineer, but I can't imagine that
leaving out the internal DAC would save any money at all.
Instead, I would bet a beer that it would net out to
costing more.

In ancient postings, one of the Slim engineers said
that the display was the largest cost part of the SB1.

If they just left out the part, it would save at most
the price of the DAC chip. Since the whole
thing sells for under $300 and the wired version
for under $250, it is hard to imagine that the
DAC itself costs more than $20.

They would then have to have two products, two
sets of packaging, separate QA procedures, etc.
They would accidentally ship some normal products
to audiophile customers, and some audiophile
products to normal customers, and the labor to
straighten it out would destroy any savings.

It they designed a special model, without the DAC
support circuits, they would have two more radically
different products, with _all_ of the same problems
listed above.

Set the volume on wide open and ignore it.

AES connections over XLR would be cool,
but from a practical matter, the cable lengths
are way too short to care. It is hard
to imagine that an audiophile would have the
squeezebox more than a meter away from the
preamp/amp. At those distances, cables are
snakeoil.

Put a brick on top to keep it from moving.
Or better yet, I'll get a huge aluminum
heatsink and sell it as a critical cooler and
weight to keep it from moving.

A more serious remote would help the marketing
for audiophiles, but I'm not at all sure
that there are enough audiophiles that
are computer literate enough to be a market.
You can always just buy a Harmony remote.

BTW, my Classe integrated amp has a wonderful
remote. Feels machined out of a billet of metal.
Very cool. But, no one has the IR codes for
Classe stuff, so I have to get a learning remote
to be able to reduce my collection of remotes.
There probably is a market for taking the
Harmony remote and wrapping it in $20 worth
of metal and selling it for $500 :-)

Pat

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

WSLam
2005-06-21, 22:55
Pat, you made some very practical comments. perhaps audio nuts like me are not very practical to begin with! =)
It does a fine job as is now, but I cannot imagine this is now a 'done' deal. I am sure further improvements can be made. I would think that Slim Devices has a bigger 'ambition' then that.

julian2002
2005-06-22, 00:01
certainly a higher quality digital outputs aes/ebu, spdif coax and optical at/st glass optical.
better psu.
internal shielding between audio and support circuitry.
standard hi-fi sized case.
separate power lead.
audiophile internal components (black gates, oscons, holco, etc..)
cheers


julian

Fabrice Rossi
2005-06-22, 00:59
Hi.

What I would really need is a top quality _scientific_ analysis of the
possible jitter issue of the SB2 digital out, used with a standard
cable, something Sean was not able to do at high resolution because of
the cost of the analyzer. Then some optimization could be done by using
a higher end clock or something else. The transport part is nice because
this is something that can be tested on pure objective basis.

For the rest, I'm quite happy with the SB, but it would be nice if
slimdevices could come up with their own NAS, something like the kuro
box but with the slimdevices outstanding support quality. Nothing to do
with sound quality, however...

Fabrice

Fabrice Rossi
2005-06-22, 01:00
Pat Farrell a écrit :
> If they just left out the part, it would save at most
> the price of the DAC chip. Since the whole
> thing sells for under $300 and the wired version
> for under $250, it is hard to imagine that the
> DAC itself costs more than $20.

The DAC is a Burr-Brown PCM1748. According to TI web site
(http://focus.ti.com/docs/prod/folders/print/pcm1748.html), the price is
1.3 US $ if you buy 1000 units. Your are therefore completely right.


Fabrice

Steve Agnew
2005-06-22, 13:08
Well, why not!

Regards, Steve.

Andrew L. Weekes
2005-06-22, 13:28
Steve,

That's hilarious - nice editing job.

Andy.

Andrew L. Weekes
2005-06-23, 14:56
What would people pay for a true 'audiophile' version of the Squeezebox?

Traditionally 'audiophile' products are expensive, for which there are several reasons, some reasonable, some simply marketing based. Some of it is related to perception (i.e. it can't be any good unless it's pricey - the Stereophile effect, if you will) but at least as much, in a truly well-engineered product, is related to the very significant design effort needed to produce something that sounds great and keeps you from your bed, or the TV, in pursuit of music.

Couple that to the ever-shrinking market for two-channel only audio systems and the development costs take on a whole new meaning; the simple commercial reality is that they have to be spread across the potential number of customers for that product. For a Linn CD12 that number runs to just thousands, worldwide, I suspect, hence the huge price tag.

The SB2 as it is is a wonderfully elegant, modestly sized, reasonably easy to use, immensely practical device, that gives great access to a wide range of media, which as a user I love.

I don't personally feel it can currently feed my main system though as a main source having tried it. I would actually love that it did it all, but interestingly there's not much talk about the *sound* above!

The point is that for me, as a consumer (rather than an engineer) what goes on inside the box should be irrelevant, it's what comes out that matters. What comes out is very much related to what goes on internally, but I'm curious as to whether the comments above are just becuase the SB2 is *perceived* as not being audiophile (because it doesn't tick the right boxes and looks like a radio alarm clock) or whether people identify, as I do personally, that there's something missing from the results it produces?

Lots of meaningless (in my view) talk about components, interfaces, design implementation, features (absent or not) but nothing about the most important thing of all - the music!

Surely the purpose of an audiophile version would be to sound as good, or better, than whatever your own personal quality reference is?

If, for example, you are comparing to a Linn CD12 at 12000GBP, it's going to be hard to expect that level of performance for significantly less than that.

I think the current SB2 is a marvellous piece of superb engineering, but am curious as to how much people are seriously prepared to pay for a product that competes with some of the other audiophile standards out there.

Curiously, my own absolute standard, in terms of musical enjoyment, is still the vinyl record, courtesy of a Linn LP12 turntable. No CD player, or any source (with the possible exception of a good FM tuner and broadcast) I've yet heard comes close to it!

Andy.

Aylwin
2005-06-23, 16:20
While a hi-end audiophile version of the SB would be nice, I don't think it's practical for Slim Devices to get into it. Currently, the audio quality is already very good and there are many other things to work on (e.g. SW).

I think mods are the way to go. Some enterprising and technically competent person should buy a few SB2's, mess around with them and then try to develop mod packages. I'm sure quite a few audiophiles out there would be willing to have their SB2 modded.

In the end though, it's still PCM and many audiophiles will prefer SACD and/or analog (vinyl records) for their serious listening. For me, it's SACD and I doubt any amount of hardware changes to the SB2 (or any other CD player, for that matter) will make it sound better than the SACD sound that I like.

pfarrell
2005-06-23, 17:47
On Thu, 2005-06-23 at 16:20 -0700, Aylwin wrote:
> I think mods are the way to go.

I tend to think so as well.
Maybe package the mods and sell them if it works great.

Back before the SB2 I was thinking of taking a SB1 and
a Benchmark DAC-1, putting them in a single case of heavy
metal and selling it for $2000.

> In the end though, it's still PCM and many audiophiles will prefer SACD
> and/or analog (vinyl records) for their serious listening.

I hear you, and read about it, but don't understand.
I can see SACD over red book, but don't see any
reason that 24/96 PCM can't do as well.
I do all the recording in my studio at 24 bits, and use
96k when there is any hope that folks will care
about quality.

It is about impossible to get a real test comparing them.
All of the stereo mags tests seem to compare SACD to redbook.
Of course, the labels have no incentive to release the same
recordings in both formats so that they could be compared.

It was interesting to see Stereophile test SACD disks
a few months back. Many of them (most?) had no signal
above 20kHz. Probably because they were just remasterings
of low rate PCM in the first place.

It is pretty clear to me that DVD-A and SACD are dead for
any real volume. Perhaps dual-disk will work, altho I'm skeptical.

The folks who really care use LPs, and there will always
be a niche market to support them. But it is not
at all clear how there can be new material, most
orchestras & symphony groups are no long able
to get funding to record (Naxos the exception that
makes the rule, and they are not hi-fi)


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

WSLam
2005-06-23, 23:11
Andy,

I own a Linn CD12.

I did a little experinment the other night.

Comparing the CD12's analog output and the SB2's analog output is simply unfair. So that is imo, NOT a valid comparison.

But comparing the CD12's Digital out and SB2's Digital out, the difference is so small I find it negligible. (feeding both signals into the same TacT RCS2.0s DAC for a lack of a better option (considering EMM Lab))(SB2 using Audio Note Sogon cable, Linn using Siltech G5 cable). I try to be as honest as I can be and often put myself in the 'blind test' position. The only difference I could tell is that the SB2 seems to be slightly less dynamic. Other then that, I can't tell them apart.

Audiophiles are often more then just after sound. We want 'quality', we want well built, sturdy stuff. SB2 + Slimserver has so much potential to explore other segments of the mkt, hence the thread.

If enough 'science' can be proven for a bit perfect source, I will be happy to pay a lot more then what SB2 is selling for now...

Andrew L. Weekes
2005-06-24, 01:43
But comparing the CD12's Digital out and SB2's Digital out, the difference is so small I find it negligible.

This is exactly as should be the case, providing: -

1. the SB2's digital out is bit perfect
2. the external DAC can effectively de-jitter the SPDIF stream and render differences between the CD12 and SB2 negligible.

The comparison you've made is not between CD12 and SB2, but mainly how sesitive your DAC is to jitter on the incoming data stream.

For me an audiophile SB would have to stand on it's own - I would want to buy a box, plug it in and get great music, but that's quite an engineering challenge, especially if one wants to keep the flexibilty of the device!

I think you've answered my question though that it's more to do with perceived quality* of the product, than sound quality, for many.

Andy

*This isn't meant in any way to be derogatory, the SB2 is a very well built and engineered device considering it's incredible value for money, but obviously doesn't feel like a big heavy several thousand pound / dollar CD player.

Aylwin
2005-06-24, 03:44
Back before the SB2 I was thinking of taking a SB1 and a Benchmark DAC-1, putting them in a single case of heavy
metal and selling it for $2000.Actually, I think SB2 + Benchmark DAC-1 would make an even better combination. It's something I'd be interested in and certainly worth $2K if put together nicely. Another option, would be to put the SB2 in a larger case and include: an internal power supply, super regs for the chips, better caps, ultra-low jitter clock, Bybee filters, etc.


I hear you, and read about it, but don't understand. I can see SACD over red book, but don't see any
reason that 24/96 PCM can't do as well.To be honest, I don't fully understand either. I can hear the difference between SACD and RBCD but not necessarily between SACD and DVD-A. But like you say, I haven't been able to compare the same material on both formats. Then there's the issue on whether the master is on analog or DSD, or, PCM.

Another issue is universal players that use multi-format DACs from the likes of Burr Brown. Apparently, these universal players convert the DSD bit stream to PCM before conversion to analog which defeats the purpose of DSD. I have one such player and the sound is pretty much the same regardless of format.

I have since acquired a "real" SACD player which maintains the DSD bit stream all the way through to the analog section. In fact, it doesn't pass through any DAC at all (I don't really understand this but it has to do with low pass filters or something). Anyway, the sound is amazing. I've read about SACD sounding analog while other PCM based formats sound, well, digital. I can't say anything about that as I have little experience with hi-end analog systems to compare with but I guess what I'm hearing is what "they" are talking about. Then again though, I have no DVD-A player of equal quality to compare against.


It is pretty clear to me that DVD-A and SACD are dead for any real volume.Sad but true. Format wars are silly. But if any one of them has a chance it's probably SACD with its hybrid discs. These discs (costing more or less the same as a regular CD) contain both SACD and RBCD layers allowing payback on normal CD players.


The folks who really care use LPs, and there will always be a niche market to support them. But it is not at all clear how there can be new material,There's some but not much. For example, there's Mobile Fidelity: http://www.mofi.com/ I have a Patricia Barber SACD from them and audio quality is simply stunning. They release on vinyl too so I assume those would be top notch as well.

pfarrell
2005-06-24, 08:57
On Fri, 2005-06-24 at 03:44 -0700, Aylwin wrote:
> Then there's the issue on whether the master is on analog or DSD, or, PCM.

I believe, without benefit of any inside information,
that Sony pushed SACD because they own a huge library
of music, most of which is on 2" analog tape.

The analog tape ages and is fragile, they needed an
archive medium so they could protect their very
expensive assets and be able to sell them to us
a third or fourth time when Smell-o-vision media
is invented in 2045.

If you don't have a huge library of analog
then SACD loses a lot of its appeal. Of course
both DVD-A and SACD were supposed to include DRM
and prevent copying, but as usual, that didn't happen.

>From the recording studio side, 2" tape is only used
in rare occasions. Hi/wide PCM gear is much more
readily available than DSD stuff. All the editing
and looping stuff used for pop is PCM. ProTools,
which is used by nearly all the top shops is PCM.
The last 2" tape manufacturer ended production
a few months ago, but some niche players have already
announced that they will pick it up. A lot of this
is cost based. a reel of 2" tape is about $150 and holds
about 20 minutes at 30ips. A day in the studio can use
thousands of dollars worth of tape.

The sad reality is that the mass market provides most of the
material, and the mass market doesn't care a hoot about
quality.

BTW, most "master" tapes are 1/2 inch two track.
The 24 track 2" tapes are mixed down to two tracks,
and then mastered by a separate engineer.
A well done AAA recording would be third generation,
first the 24 track 2" session tape, then the
1/2" (sometimes 2" two track) mix tape, and then
the two track tape sent to the LP pressing plant.
Mastering for vinyl is voodoo.

--
Pat Farrell PRC recording studio
http://www.pfarrell.com/PRC

Fabrice Rossi
2005-06-24, 09:13
Pat Farrell a écrit :
> Of course
> both DVD-A and SACD were supposed to include DRM
> and prevent copying, but as usual, that didn't happen.

Really?

The high definition content of SACD is protected at the physical level
and it seems nobody as cracked it yet (see
http://en.wikipedia.org/wiki/SACD). Of course, the standard PCM content
is not really protected.

The DRM of DVD-A is similar to the one of DVD (the famous CSS), but it
has not been cracked (see http://en.wikipedia.org/wiki/DVD-Audio).

The funny thing about those DRM systems is that you can digitize back
the analog output of your player with sufficient quality to produce the
low bitrate MP3 everybody is downloading from P2P network. So they
basically bother people who are ready to buy the things...

Fabrice

pfarrell
2005-06-24, 09:31
On Fri, 2005-06-24 at 18:13 +0200, Fabrice Rossi wrote:
> Pat Farrell a écrit :
> > Of course both DVD-A and SACD were supposed to include DRM
> > and prevent copying, but as usual, that didn't happen.
>
> Really?

yes. it really doesn't protect the data.

> The high definition content of SACD is protected at the physical level
> and it seems nobody as cracked it yet

Not clear that anybody cares to. There are very few SACD only
recordings, and only a tiny percentage of them would be of
interest.

You show a clear way to achieve this later in your note.

There is not much of a conceptual challenge to cracking any
cryptography used by any of the schemes. Good cryptography
is about key management. To have a real DRM for hardware
players, each player would have to have unique keys. This
is against everything that mass market manufacturers want.

Doing real cryptography is a lot easier on networked computers,
especially with things like the CPU-identification number
that Intel put in the Pentium-III.

It is impossible to "copy protect" digital media.
It is possible to prevent usage of the copied data
when you use real cryptography.

But this is gettting way off topic for Slim Audiophiles.
Contact me off list, or check out the serious
cryptography lists for more.


> The DRM of DVD-A is similar to the one of DVD (the famous CSS), but it
> has not been cracked (see http://en.wikipedia.org/wiki/DVD-Audio).

Again, mostly because there is no reason to work that hard.
CSS was trivial to break.


> The funny thing about those DRM systems is that you can digitize back
> the analog output of your player with sufficient quality to produce the
> low bitrate MP3 everybody is downloading from P2P network. So they
> basically bother people who are ready to buy the things...

With a two hundred dollar audio card, you can play the multi-track high
res audio out, and re-digitize it at 24/96kHz. Less money for stereo.

While it may not be technically bit perfect, who is going to be able to
tell one bit mis-quantitized? I maintain that lots of cheap "pro audio"
cards can do the job well enough to recover the 100dB signal to noise
ratio that the fundamental recording gear has. And with 20hZ to 50kHz
bandwidth.

It is perfect enough that you can return to arguing about which
$500 interconnect cable is better.


--
Pat Farrell PRC recording studio
http://www.pfarrell.com/PRC

Fabrice Rossi
2005-06-24, 10:27
Pat Farrell a écrit :
>>>Of course both DVD-A and SACD were supposed to include DRM
>>>and prevent copying, but as usual, that didn't happen.
>>
>>Really?
>
> yes. it really doesn't protect the data.

Well theoretically, you're right, but see below.

> There is not much of a conceptual challenge to cracking any
> cryptography used by any of the schemes. Good cryptography
> is about key management. To have a real DRM for hardware
> players, each player would have to have unique keys. This
> is against everything that mass market manufacturers want.

Right, but this is exactly what is happening. In order to play SACD, you
must get a key from Sony. They will give you one only if you sign a lot
of paper. And they don't give a key for software players as was done for
DVD. And the same is true for DVD-A. You won't find software player
(however there are software authoring tool and they might be decompiled,
I guess).

> Doing real cryptography is a lot easier on networked computers,
> especially with things like the CPU-identification number
> that Intel put in the Pentium-III.

Which is disabled. But new things are coming from Intel and AMD, you're
right.

> It is impossible to "copy protect" digital media.

You can protect authoring of a compatible copied media. This was done
for DVD. In order to make a bitwise copy of a DVD that includes the
keys, you need a specific hardware that is very difficult to get. Of
course organised "piracy" has it. And if you request for all the digital
path to be encrypted, you will only be able to copy the analog output
(yes I mean HDCP), unless you reverse the hardware, which is doable, but
quite difficult, especially if you use smartcard like technology.

> It is possible to prevent usage of the copied data
> when you use real cryptography.

And this is what is used by DVD, SACD, DVD-A, console games, etc.. As
you said before, the problem is the key(s). Basically the media key is
put on the media itself (for DVD, SACD and DVD-A). In order to get it,
you need a player key. The media key is encoded by a bunch of player
keys and all those keys are written on the media. If you know one of the
keys, you can get the media key and decode it. So you have to keep the
keys secret, which is difficult, but doable with hardware only decoders.
For console games the trick is based on a signature but this is the same
idea.

>>The DRM of DVD-A is similar to the one of DVD (the famous CSS), but it
>>has not been cracked (see http://en.wikipedia.org/wiki/DVD-Audio).
>
> Again, mostly because there is no reason to work that hard.
> CSS was trivial to break.

Not so much. It was because a software player was badly written and both
the key and the algorithm appeared. Then it also appeared that the CSS
algorithm was very weak and can be broken easily. Everything is based
on the fact they allowed software player. This is not going to happen again.

> With a two hundred dollar audio card, you can play the multi-track high
> res audio out, and re-digitize it at 24/96kHz. Less money for stereo.
>
> While it may not be technically bit perfect, who is going to be able to
> tell one bit mis-quantitized? I maintain that lots of cheap "pro audio"
> cards can do the job well enough to recover the 100dB signal to noise
> ratio that the fundamental recording gear has. And with 20hZ to 50kHz
> bandwidth.
>
> It is perfect enough that you can return to arguing about which
> $500 interconnect cable is better.

I fully agree. But the "content industry" is trying to push for a pure
digital encrypted path for high quality content. At the end, it will be
possible to tape a movie displayed on you high res plasma screen, but
they are trying to make sure it's going to be the only way to copy a
movie. They wan to kill the analog path, at least for movies in the
future format. Will they succeed?

Fabrice

Yannzola
2005-06-24, 17:23
How about a 75 ohm BNC SPDIF out?

y.

dean
2005-06-24, 17:43
I've seen these on some equipment, is there consensus (audiophiles,
consensus? HA!) on BNC vs. RCA for S/PDIF?


On Jun 24, 2005, at 5:23 PM, Yannzola wrote:

>
> How about a 75 ohm BNC SPDIF out?
>
> y.
>
>
> --
> Yannzola
>

JJZolx
2005-06-24, 19:43
> I am so happy with the SB2 (replacing slowly, my Linn CD12)
> that I really hope SD will build an 'audiophile' version of
> the SB.
>
> Here are a list of features I could think of! Hope you guys
> can all pitch in:
>
> No Internal DAC. Save the cost, and spend it on elsewhere


Keep the internal DAC and the analog outs. If many of the other suggestions are made, it would no doubt sound all the better.

One thing I think should be kept in mind, even as an "audiophile" targeted product, is use within a second or third audio system. Eliminating the perceived need for an external DAC simplifies such a system greatly. But, of course, leave the option to add the external DAC as you have now.


> - No Volume control, the simpler the circuit, the better


I'm wondering if this would make any difference. Isn't the current volume control digital? Easily bypassed if so.


> - WBT or Neutrik connectors


Absolutely. Get them off of the motherboard as well. I'm guessing that a daughter board for the rear connectors might be needed. Or maybe they can just be wired to the current motherboard.


> - Make it heavier! =) audio nuts are all for heavy equipment!
> (otherwise, the AES cable is gonna make the SB2 'move')


Yes. The chassis and overall aesthetics are vital. I'm not necessarily a proponent of making it a standard 17" width chassis, though. There are many good examples of smaller form factor chassis. If I could place the Squeezebox2 Audiophile(tm) next to a DAC on an equipment rack, or put both on top of an integrated amp in a bedroom system, then I'll be happy.

Needs to have an all metal chassis, with a nicely finished, heavy aluminum front plate. No more silver paintjobs done at the local auto body shop. :-)

A power switch, either front or rear mounted is also a necessity. There's nothing that feels cheesier than having to unplug a device from the mains just to reset it whenever it goes braindead.


> - A even better, higher resolution display.


Maybe. I think the thing here is that it could only be bigger and/or have higher resolution. Maybe it would be viewable from further away, but without programming changes in SlimServer, there'd be no additional information displayed.

I suspect that whatever changes are made to the physical device, asking that the programming of SlimServer distinguish between the Squeezebox2 and the Squeezebox2 Audiophile in order to support added functionality would likely kill any possibility of it ever becoming a product.


> - more 'solid' feel remote control


Unimportant for me, but not a bad idea. Could just be an upgrade, even to the current models.


> Anyone else?


A much better, linear power suppy, with IEC connector. I think an internal power supply in a larger chassis would be great. Or perhaps a power supply in a matching metal chassis would be easier to do.

Add some chassis vibration damping. And RFI shielding, especially of the wireless section.

My biggest question is whether some of the enhancments would require a new motherboard design. Hopefully it would not, and the CPU and the wireless boards could just be unstacked and seperately mounted within the chassis, with flat cables running to the current board connectors.

Certainly nice would be enough chassis mounted buttons (or dials or rotary knobs) to replace/emulate much of the remote's functionality. There's just something about a device that cannot be operated at _all_ except by remote control. It's one thing to have added functionality on the remote - for instance, programming a track sequence on a CDP - that can't be done from the player's buttons, but not being able to operate a piece of audio equipment by physically manipulating controls on the device itself is something different.

JJZolx
2005-06-24, 19:48
Back before the SB2 I was thinking of taking a SB1 and
a Benchmark DAC-1, putting them in a single case of heavy
metal and selling it for $2000.

Another possibility might be if Slim Devices could work with some DAC manufacturer, or manufacturer_S_ and package the Squeezebox2 "engine" such that it could be dropped into the DAC and make it ethernet/WIFI enabled. My biggest reservation here is that I and many others would still want a Squeezebox2 Audiophile _transport_ for the DAC of our choice.

pfarrell
2005-06-24, 20:22
On Fri, 2005-06-24 at 17:43 -0700, dean blackketter wrote:
> On Jun 24, 2005, at 5:23 PM, Yannzola wrote:
> > How about a 75 ohm BNC SPDIF out?
>
> I've seen these on some equipment, is there consensus (audiophiles,
> consensus? HA!) on BNC vs. RCA for S/PDIF?

Ha is right.
My benchmark DAC-1 has BNC for S/PDIF
as does most of my studio gear ("pro audio" or
better). [any gear with "pro" in its marketing
name is really aimed at amateurs.]


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

Triode
2005-06-25, 05:34
I've see quite a lot of audiophile gear with BNC rather than RCA - many shiped with a BNC to RCA converter for those who wanted RCA.

Of course this didn't actually mean that the transmitter circuit had a source impedance of 75 ohms (though you would hope so!) With a true 75 source, transmission line with 75 ohm BNC connectors and termination at 75 ohms, this should minimise reflections and hence reflection induced jitter in simple receiver circuits.

Adrian

Andrew L. Weekes
2005-06-26, 13:02
I've seen these on some equipment, is there consensus (audiophiles,
consensus? HA!) on BNC vs. RCA for S/PDIF?

The simple fact is that compliance with the consumer spec. mandates RCA, but this will *always* sound worse, unless the external DAC is completely insensitive to incoming jitter (e.g. Benchmark DAC1) since the RCA can never be a true 75R. AES / EBU allows XLR's, which are nominally 110R, but these have discontinuous impedance characteristics, which makes them pretty poor too (but not as bad as RCA).

The reflections introduced will add significant jitter, for many consumer grade units the jitter on SPDIF with an RCA is likely to be in the order of 500-1000ps, with a really good one being maybe 10ps. You want low picoseconds here...the sonic results usually largely depend on how well engineered the DAC is.

The numbers are misleading too, the spectral content of the jitter is more important than the absolute jitter numbers.

Even with a BNC it's hard to get it right, but at least it's not intentionally handicapped from the outset.

I'm interested in the responses here, as if one likes the sound of the Benchmark DAC, then using it with the Squeezebox is audiophile quality, providing the data is bit perfect from the SB2, which we are assured it is (and I have no reason to doubt).

The diffculty is that to support the multiple sample frequencies required makes the design job MUCH harder, if an audiophile Squeezebox were to have an internal DAC, since the distibution and switching between clocks whilst trying to retain the jitter performance required, is a big job.

I'm going to try feeding a clock straight into the DAC on my SB2 at some point, just for 44.1k FLAC replay, to see how much difference it makes.

Andy.

Andrew L. Weekes
2005-06-26, 13:28
Interesting to still see so much about looks, and features, but none about the sound...

Just to provoke and stir things up, here's what I'd personally do if I were to design a networked music device along similar lines...

1. Single sample frequency support (44.1) for ripped CD replay only, all other formats can be sample rate converted at the Server end.

2. Internal DAC, with a good clock.

3. Better filtering at the o/p, with good line driving capability, maybe balanced as well as single ended.

4. Change the display (VFD's are very noisy and require a fair bit of work to eliminate their ills) and use something more benign.

5. Still have the digital volume control, since the option is always there to fix it at max, for best quality.

6. Make it sound so good you don't want to go to bed at night (which means lots of work in lots of areas, but it's ultimately the only thing that matters to me).

The rest is just froth, although some is a case of form from function.

Andy.

BTW, the remote supplied may be cheap and light, but it's great, ergonomic and I can use it with my eyes closed or in the dark. Most audiophile equipment has rubbish remote controls that are expensive and unuseable, I'd rather see the money spent where it matters.

Carl W. Irving
2005-06-27, 08:39
If I may put in my $0.02:


> 3. Better filtering at the o/p, with good line driving capability, maybe balanced as well as single ended.

I don't have an SB2 (yet) to comment on the current filter quality, but I think that balanced outputs might open interesting new applications for the SB even if they may, strictly speaking, be non-audiophile markets. For example, professional users tend to recognize equipment qualities that are congruent with what the audiophile looks for, so addressing both may help sustain sales volumes that are more viable.



> 4. Change the display (VFD's are very noisy and require a fair bit of work to eliminate their ills) and use something more benign.

Well, except that the VFD is one immediate hook for the vast majority of people that would buy an Audiophile SB... Let's face it, most people, audiophile or not (OK, mostly not), want their expensive toys to look cool and expensive... A VFD is a key differentiator in that respect. Slap an LCD in there and you immediately get compared to the $150 LCD-based Roku at Radio Shack, the Turtle Beach Audiotron or something else equally irrelevant to the audiophile market. It is an unfair comparison, but that doesn't stop people from making it.

I don't dispute your arguments regarding VFD display noise, I'm just saying that it is pretty much a given that they just have to be worked around. Which leads to...

> The rest is just froth, although some is a case of form from function.

Except that some froth is necessary to commercial success, even in high-end gear. :-)

Yannzola
2005-06-27, 11:09
[QUOTE=Andrew L. Weekes]Interesting to still see so much about looks, and features, but none about the sound...[QUOTE]

I have to agree with Andy here.... sound is what ultimately matters. No amount of dolling up the case will substitute for that.

If the cost of integrating an uber-audiophile class DAC in the SB is too cost prohibitive, how about focusing on making the SB as transparent and user upgradable/tweakable as possible? The existing dac could be kept in place for those on a budget (like me), but entirely and cleanly bypassable (sp?) for those who would rather run an external unit.

Perhaps the PSU portion of the Audiophile SB could also be made similiarly "transparent". Allowing the user to either use the standard wallwart, or to bypass this circuitry entirely with some sort of external linear PSU.

???

y.

Andrew L. Weekes
2005-06-27, 14:31
Yannzola,

Thanks for the well thought out response.

Except that some froth is necessary to commercial success, even in high-end gear. :-)

Of course you are right, remote control and other luxuries that I wouldn't leave out are all part of the 'problem' as well as part of the practical solution.

Perhaps the PSU portion of the Audiophile SB could also be made similiarly "transparent". Allowing the user to either use the standard wallwart, or to bypass this circuitry entirely with some sort of external linear PSU.

Plug in external PSU's are a very common upgrade path to some manufacturers. it can allow huge gains in an easy to implement manner, my only criticism of it (as a man who currently has 4 external PSU's on his rack of kit) is it's less elegant aesthetically, cables etc. lower the WAF*

My post was partly aimed to provoke - I always find it interesting when people see particular features as being 'audiophile' as if by some magic they automatically enhance a product, when in most cases they don't and can even make it worse. You can make most things sound good, but only if they are well-designed, just throwing parts at something (like special caps, expensive connectors etc.) are no guarantee of performance. You have to know when, where and how to use them.

Most big heavy RCA plugs for example sound far worse than some of the cheaper varieties. The best by far are the ludicrously flimsy but lightweight and highly conductive 'Bullet' plugs, in my experience.

You can't get away from the problem though that the more features one adds, the more work it usually results in - VFD's, fast CPU's doing lots of work, wireless modules etc. all add up to an EMC situation that's anathema to good audio.

It's hard to shut down the micro though in a device that's fundamentally micro-controlled though, so it's just something that has to be dealt with. It's not impossible, but it adds cost that gives you no benefit whatsoever in terms of sound and adds work just to enable you to keep stationary, before you even try to progress forward sonically. It's all part of the fun of engineering!

But 'the high end' is as much about appearance, looks and labels, in many cases, as it is about sound quality, with a few exceptions. To some it's a status symbol to be displayed - to me I'd like a tiny invisible box that only draws attention to itself by dint of the music it plays, rather than the room-dominating rack of kit I currently own ;)

Andy.

P.S. I haven't looked, but I'm amazed that with current LED technology someone hasn't come up with an idea for a VFD replacement, with all the brightness capability (and possibly more) a wider range of colour options, but a far more benign electrical and EMC environment. Maybe I should have patented that idea...:)

*Wife Acceptance Factor, for those that don't know!

Fabrice Rossi
2005-06-28, 00:51
Yannzola a écrit :
>If the cost of integrating an uber-audiophile class DAC in the SB is
>too cost prohibitive,

I would say that the DAC chip itself is not a problem. Very high end
chips from Burr Brown cost less than 20 $ (if you buy 1000 chips) and
they are used in highly praised CD players. The problem I guess is
everything that goes around the DAC...

Fabrice

WSLam
2005-06-28, 03:24
I think by eliminating what SD cannot do 'best' (ie DAC) i would argue that the perceived value of the device would be higher. (perfect transport substitute vs a perfect transport substitute and a so-so cd player substitute)...

Andrew L. Weekes
2005-06-28, 05:22
I think by eliminating what SD cannot do 'best' (ie DAC) i would argue that the perceived value of the device would be higher.

I don't think this is the case, as it's based on the premise that designing something as a transport is somehow easy.

The reality is that 99% of external DAC's have a jitter transfer function, to get the best performance from an external DAC therefore requires detailed work on the digital out side of things, which is similar in nature, if not in absolute volume, to that required for a DAC implementation.

In fact, by placing the DAC externally you make it harder to acheive the ultimate performance levels, since the digital interface is an additional source of jitter which is over and above that you acheive inside the player.

Andy.

WSLam
2005-06-28, 10:49
Yes I understand, and believe in that principle, hence I own a Linn CD12.
However, I find it hard to believe that SB2's internal DAC can ever be as good as some of the best DAC/players out there without hiking up the cost. I was just suggesting that for the 'audiophile model' of the SB2, leave the DAC out.
yes, doing a bit perfect transport seems easy enough, but it's always the 'last little bit' of imperfections that differentiates the great, and the greatest.

ws

Yannzola
2005-06-28, 11:18
In fact, by placing the DAC externally you make it harder to acheive the ultimate performance levels, since the digital interface is an additional source of jitter which is over and above that you acheive inside the player.

Andy.

What about creating a co-branded product? I'm thinking of Benchmark Media in particular. You could market the product as having the best of both worlds... the ultimate low jitter / high convinience transport + the best-value NO jitter DAC available.

This could open up a new market for Benchmark, as well as strengthen the Squeezebox's position as =the= audiophile music server solution.

Is UltraLock™ Technology licenseable? Could it be integrated into an SB? Dunno.



y.

kjg
2005-06-28, 11:45
Even within the audiophile market, sound is not the only consideration,
and looks, features and the cool factor still play a part. The number of
audiophiles for whom sound is the *only* consideration is a smaller
percentage of the total market (e.g. those that read Sterophile and TAS,
buy high quality gear gear and enjoy excellent sounding music). Some
audiophiles buy super expensive cables, some do not yet they are all
part of the audio-enthusiast market. Both audio and aesthetic
considerations need to be accounted for in this market, and nearly all
of the audiophiles will buy in, even at a higher price to get the total
package.

- Ken

Yannzola wrote:

>Andrew L. Weekes Wrote:
>
>
>>Interesting to still see so much about looks, and features, but none
>>about the sound...> > >
>>
>>
>>>I have to agree with Andy here.... sound is what ultimately matters. No
>>>amount of dolling up the case will substitute for that.
>>>
>>>If the cost of integrating an uber-audiophile class DAC in the SB is
>>>too cost prohibitive, how about focusing on making the SB as
>>>transparent and user upgradable/tweakable as possible? The existing dac
>>>could be kept in place for those on a budget (like me), but entirely and
>>>cleanly bypassable (sp?) for those who would rather run an external
>>>unit.
>>>
>>>Perhaps the PSU portion of the Audiophile SB could also be made
>>>similiarly "transparent". Allowing the user to either use the standard
>>>wallwart, or to bypass this circuitry entirely with some sort of
>>>external linear PSU.
>>>
>>>???
>>>
>>>y.
>>>
>>>
>
>
>
>

Yannzola
2005-06-28, 11:52
Is UltraLock™ Technology licenseable?

Perhaps UltraLock™ =is= licenseable! It appears that it is currently being used in a variety of digital video decoders. The Benchmark DAC appears to be the first, and so far only pure audio implementation of the technology.

Or... more likely... I could be confusing two similairly named technologies?

???

y.

Yannzola
2005-06-28, 13:11
Even within the audiophile market, sound is not the only consideration,
and looks, features and the cool factor still play a part.

I agree, to a certain degree.
In my opinion, the new look of the SB2 =is= cool. Minimal, with that oh-so-chic bulbous-yet-tapered look. If I were to redesign it, I would keep the small form-factor and basic shape, but improve the quality of the materials used. Brushed aluminum with maple or beech accents? A thicker fancier power cable (ideally attached to a better internal or external PSU)... something braided and translucent? "Sexier" product packaging?

IMHO Good design doesn't draw attention to itself. Really good design is invisible.

Here's a wacky idea: what if the SB interface was capable of being projected on a wall, with the unit itself hidden out of sight?

y.

seanadams
2005-06-28, 18:25
Perhaps UltraLock™ =is= licenseable!
As good as the benchmark DAC is (and it is very good IMHO) there is nothing mysterious inside.

It's some simple 3-terminal regulators, off-the-shelf DIR and DAC chips, and inexpensive, standard op-amps.

The benchmark DAC is living proof that audiophile quality is all about GOOD DESIGN, not exotic parts. Good marketing (Ultralock™) is what sells it, but it has nothing to do with what's inside. As Andrew says, it's all about the sound. You do need more than good sound to make it sell though - throwing a little xxxxx™ in there never hurts. We have SlimDSP™, for example. :)

Yannzola
2005-06-28, 21:07
As good as the benchmark DAC is (and it is very good IMHO) there is nothing mysterious inside.

It's some simple 3-terminal regulators, off-the-shelf DIR and DAC chips, and inexpensive, standard op-amps.

Doh!
I thought Ultralock was some fancy patented hardware that somehow magically eliminated jitter. It's obvious I really don't know what I'm talking about ;)

BTW: I think it's fabulous that you take the time to interact with your customers directly. That's very very cool.

y.

pfarrell
2005-06-28, 21:14
On Tue, 2005-06-28 at 21:07 -0700, Yannzola wrote:
> Doh!
> I thought Ultralock was some fancy patented hardware that somehow
> magically eliminated jitter. It's obvious I really don't know what I'm
> talking about ;)

Don't feel bad, lots of folks talk about jitter
and I'm not sure it exists. Clock error can
exist, at least in a studio with lots of
separate gear that can each march to their own
drummers.


> BTW: I think it's fabulous that you take the time to interact with your
> customers directly. That's very very cool.

Yes, Sean and folks being accessible, and the
general Slim user community is very cool.



--
Pat Farrell PRC recording studio
http://www.pfarrell.com/PRC

Triode
2005-06-29, 10:47
Re jitter - I would suggest it is known to exist and matter, but whether it matters in your setup depends on what the designer has done to the individual components you have. Many modern dacs like the benchmark do some form of reclocking to minimise jitter and hence don't drive the dac conversion from a simple recovery of transitions on the spdif line. Hence they are far less sensitive to transport jitter and poor spdif transmission lines.

The Benchmark appears to be a well engineered, but relatively standard implementation of asychronous sample rate conversion - some details at: http://www.diyaudio.com/forums/showthread.php?s=&threadid=8078&highlight=

BTW - diyAudio's digital board is a good source of debate about jitter and all things digital.

Also while I am at it, there has been some debate on AA's computer audio asylum recently about doing resampling in software due to the improved algorithms that could be run - see: http://www.audioasylum.com/forums/pcaudio/messages/4690.html
This won't help jitter, but is interesting - perhaps slimserver could do some upsampling...

Adrian

robinbowes
2005-06-30, 03:47
Here's a wacky idea: what if the SB interface was capable of being projected on a wall, with the unit itself hidden out of sight?

Now that's one of the best ideas I've heard for a long time.

Does anyone know if such modules are generally available?

R.

seanadams
2005-06-30, 05:39
Now that's one of the best ideas I've heard for a long time.

Does anyone know if such modules are generally available?

R.

I was thinking we could drive the audio out of the s/pdif and then use the DAC to drive a pair of galvanometers with mirrors attached to them to generate the graphics, and then include a large argon laser with every Squeezebox2.

pfarrell
2005-06-30, 07:09
On Thu, 2005-06-30 at 05:39 -0700, seanadams wrote:
> I was thinking we could drive the audio out of the s/pdif and then use
> the DAC to drive a pair of galvanometers with mirrors attached to them
> to generate the graphics, and then include a large argon laser with
> every Squeezebox2.

Wow, you can get galvanometers?
Getting proper weighted VU meters is hard and expensive.

The more I think, the more a pair of proper VU meters lit
from the warm glow of a 6L6 would be about the thing.

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

Fabrice Rossi
2005-06-30, 07:17
seanadams a écrit :
> I was thinking we could drive the audio out of the s/pdif and then use
> the DAC to drive a pair of galvanometers with mirrors attached to them
> to generate the graphics, and then include a large argon laser with
> every Squeezebox2.

That would be so cool ;-)

And of course, you will provide an interface to those galvanometers?
They could be turn into fans with proper driving, I guess (you need
large needels, though).

And maybe the argon laser can be used also as an anti theft device.

And what about playing divx with the laser?

Ah, super squeezebox, I'm waiting for you...

Fabrice

Aylwin
2005-06-30, 07:41
Galvanometer? Isn't that a device for measuring galvanized iron? ;-)

max.spicer
2005-06-30, 14:37
And maybe the argon laser can be used also as an anti theft device.

I believe Microsoft could help you there. I remember reading a long time ago about how Bill has a satellite with a laser beam attached to it, capable of taking out inefficient salesmen at the touch of a button.

Max

PS Actually, that reference was from a great story about the last human on earth without windows 95. My memory told me that it was so good it was worth googling for: http://www.ijmc.com/archives/1995/November/15November1995.html. Ah, the memories!

Yannzola
2005-06-30, 18:08
I was thinking we could drive the audio out of the s/pdif and then use the DAC to drive a pair of galvanometers with mirrors attached to them to generate the graphics, and then include a large argon laser with every Squeezebox2.

Ha ha... very funny mister smarty-pants ;-)
I was thinking along the lines of those "lcd projection clocks".
But lasers would be =way= cooler... great idea!

y.

seanadams
2005-06-30, 22:48
Galvanometer? Isn't that a device for measuring galvanized iron? ;-)

Heh. I'm not making this up - it could be done. Would use the headphone jack to do the blanking (and drive color filters maybe):

http://www.laserfx.com/Works/Works3S.html

Oh, to have more hours in a day....

Aylwin
2005-06-30, 23:08
Good link! I actually know how galvanometers work but not how they were used in laser projection. Cool stuff!

Okay, I'll add that to my wish list. :-)

In the meantime, how about a more simple choice between composite and s-video outputs? And while we're at it, we might as well add video streaming support and streaming of DD and DTS signals. The audiophile part of it would be the possibility to turn off the video circuitry. :-)

julian2002
2005-07-01, 00:37
come on, anything tainted by 'video' is inherently not audiphile.

Robin Bowes
2005-07-02, 12:28
seanadams wrote:
> robinbowes Wrote:
>
>>Now that's one of the best ideas I've heard for a long time.
>>
>>Does anyone know if such modules are generally available?
>>
>>R.
>
>
> I was thinking we could drive the audio out of the s/pdif and then use
> the DAC to drive a pair of galvanometers with mirrors attached to them
> to generate the graphics, and then include a large argon laser with
> every Squeezebox2.

Heh.

How about some sort of visual output that could plug into an external
box that could drive a computer monitor or plug into a TV or drive a
projector so we would have the option to display the SB output somewhere
other than on the SB display?

R.

Robin Bowes
2005-07-02, 12:30
Yannzola wrote:
> seanadams Wrote:
>
>>I was thinking we could drive the audio out of the s/pdif and then use
>>the DAC to drive a pair of galvanometers with mirrors attached to them
>>to generate the graphics, and then include a large argon laser with
>>every Squeezebox2.
>
>
> Ha ha... very funny mister smarty-pants ;-)
> I was thinking along the lines of those "lcd projection clocks".
> But lasers would be =way= cooler... great idea!

Yep. Me too.

It would be a nice option...

R.