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sleepysurf
2005-06-26, 19:16
I've been running my SB2 via Wireless B with SPDIF out to a Yamaha RX-V1000 (as Pre-amp, using it's native DAC), feeding a Sunfire Cinema Grand powering Martin-Logan Aerius speakers. Overall, I thought I'd achieved near CD quality, and was going to trial a Benchmark DAC1 for further improvement. On a whim, I hardwired the SB2 to my network, and was surprised to hear quite an audible improvement... tighter bass, more crystalline highs, and better imaging. Has anybody else compared Wireless B (or G), vs. hardwired Ethernet, in a higher-end system. I was quite surprised to hear such a difference. I have 2.4 Ghz wireless phones all around, and wonder if that might account for the difference. Guess I'll hafta unplug them late one evening and conduct another test. Of note, I felt the SB2 native DAC was giving me less dynamic sound vs. the Yamaha DAC, which is why I stuck with SPDIF output.

pfarrell
2005-06-26, 20:23
On Sun, 2005-06-26 at 19:16 -0700, sleepysurf wrote:
> On a whim, I hardwired the SB2 to my network, and
> was surprised to hear quite an audible improvement...

Verify that your server configuration was not changing things.
I don't speak SB2, but on a SB1, my server
automagically downconverts FLAC to MP3 to send
to my wireless unit, but leaves it alone to my
wired one.

On 802.11b, I never got good sound, or reliable connections.
The WAP was 12 feet or so from the Squeezebox


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

sleepysurf
2005-06-26, 21:01
I am streaming only FLAC files. Wireless signal strength is ~60%, with SB2 located ~75 ft from my (Linksys) Wireless B router.

I am now totally flabbergasted by the improvement when listening via wired ethernet. I just finished listening again to a demo playlist of favorite tracks, it's like night and day! Fortunately, I have USTec structured wiring running to my media wall, and can swap out an unused connector to Cat5. If the audio quality was 9/10 via wireless, it's now 10+/10 with hardwiring!

pfarrell
2005-06-26, 21:11
On Sun, 2005-06-26 at 21:01 -0700, sleepysurf wrote:
> I am streaming only FLAC files. Wireless signal strength is ~60%, with
> SB2 located ~75 ft from my (Linksys) Wireless B router.

Then it should not be doing anything, but I'd check just
to be sure.


--
Pat Farrell
http://www.pfarrell.com/

radish
2005-06-26, 21:42
There must be some downsampling going on...TCP/IP is TCP/IP regardless of the transmission medium.

Patrick Dixon
2005-06-27, 00:03
Check that Player Settings->Audio->Bitrate Limiting is set to 'No Limit'

Fifer
2005-06-27, 00:45
but on a SB1, my server
automagically downconverts FLAC to MP3 to send
to my wireless unit, but leaves it alone to my
wired one.
Pat, you can tell Slimserver not to transcode in the file preferences page.

pfarrell
2005-06-27, 00:53
On Mon, 2005-06-27 at 00:45 -0700, Fifer wrote:
> > but on a SB1, my server
> > automagically downconverts FLAC to MP3 to send
> > to my wireless unit, but leaves it alone to my
> > wired one.
> Pat, you can tell Slimserver not to transcode in the file preferences
> page.

Oh, I knew that, I was just suggesting to OP that
he check. Patrick gave the correct thing to check

I've found that I have to transcode to make the wireless one
work. It has non-audiophile speakers (self powered),
so it is OK that it not be bit perfect.

The only downside I've found is that syncing between
the wired and wireless doesn't work perfectly,
but I can live with that until the budget allows
me to buy a couple of SB2s


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

PhilNYC
2005-06-27, 12:34
At some point, I'm going to try out using a wired connection (am currently using SB2 via 802.11g). But it does make sense that the wired connection will work better than the wireless connection if SB2 powers down the wireless circuitry when ethernet is plugged in. I would assume that the RF generated by the SB2 wireless stuff would impart some noise into the audio signal...

radish
2005-06-27, 15:06
At some point, I'm going to try out using a wired connection (am currently using SB2 via 802.11g). But it does make sense that the wired connection will work better than the wireless connection if SB2 powers down the wireless circuitry when ethernet is plugged in. I would assume that the RF generated by the SB2 wireless stuff would impart some noise into the audio signal...
Yes that's a potential issue, however the OP stated he was using the digital outs. Unless his DAC/amp isn't properly shielded that shouldn't have an effect (and anyway, there's a metric f***load of RF floating around most peoples houses, I'm sure the SB2 makes little overall difference!).

PhilNYC
2005-06-27, 21:03
Yes that's a potential issue, however the OP stated he was using the digital outs. Unless his DAC/amp isn't properly shielded that shouldn't have an effect (and anyway, there's a metric f***load of RF floating around most peoples houses, I'm sure the SB2 makes little overall difference!).

I was thinking that the RF from the wireless unit would potentially affect the digital signal inside the SB2 itself as well. No way to shield the unit from itself...

sleepysurf
2005-06-28, 06:27
FYI... Bit-rate has always been set to unlimited, and volume is set at max (for digital).

My Martin Logan Aerius electrostatic speakers are particularly revealing in the highs. I first noticed the difference listening to cymbals/snares on the title track of David Grisman's Acousticity, also the sibilant highs of Norah Jones in Cold Cold Heart.

I know that TCP/IP should provide an IDENTICAL stream (either wired or wireless), so it must be some other RF or EMI issue. One thing that may be contributing in my case is that I had the SB2 sitting directly on top of my center channel speaker. It's supposedly shielded, but may be having a deleterious effect nonetheless.

I'll relocate the box, and do more listening tests later this week. Will also unplug all our 2.4 GHz wireless phones and see if there is a difference.

In the meantime, I'm curious to hear what others find if they conduct critical listening tests comparing wired vs. wireless.

MrKegFlex
2005-07-06, 09:55
I too am experiencing the same thing with a wireless SB2. Using flac files and connecting with digital coax to my avr is not producing the same sound as my cd player connected with digital coax to my avr. The sound is totally different... it really is a night/day difference. I have not had the opportunity to try the wired setup yet, I hope to try that setup before the end of the week.

MrKegFlex
2005-07-06, 10:45
I too am experiencing the same thing with a wireless SB2. Using flac files and connecting with digital coax to my avr is not producing the same sound as my cd player connected with digital coax to my avr. The sound is totally different... it really is a night/day difference. I have not had the opportunity to try the wired setup yet, I hope to try that setup before the end of the week.

I should note that I'm on a 802.11g network. Does the software do any downsampling for a 802.11b and/or 802.11g network?

MrKegFlex
2005-07-06, 12:55
I should note that I'm on a 802.11g network. Does the software do any downsampling for a 802.11b and/or 802.11g network?

I posted in haste and forgot this response from support - "the output of the SB2 is bit-perfect from the files being sent to it"

seanadams
2005-07-06, 14:30
I would strongly suggest measurements and/or blind testing for further investigation.

It is very easy to verify bit-perfect output from SB2 either by playing non-PCM material or by recording with a PC.

sleepysurf
2005-07-06, 16:15
It is very easy to verify bit-perfect output from SB2 either by playing non-PCM material or by recording with a PC.

How exactly could us "non-engineers" EASILY do this? It would be great if there is some software program that could objectively compare WIRED vs. WIRELESS streamed SB2 output (either analog or digital out). It's difficult to conduct a blind subjective test comparing the two, since you need to keep reconfiguring the setup for wired or wireless (ain't no way my wife is gonna help me with that <g>).

radish
2005-07-06, 18:45
Easy, assuming you know your way around an audio editor:

Create a small test sample (ideally a clean test tone with obvious starts and ends).
Connect the SB2 via wired, connect the digital out to the digital in of your PC.
Record on the PC, play on the SB2.
Reconnect via wifi, repeat.
Now compare the two recordings, either visually, or trim them down to exactly the same length and do a binary comparison of the resulting wav files.

I'd do it myself if I had time this evening :)

seanadams
2005-07-06, 19:26
or you can play a DTS (surround sound, i.e. "non-pcm") .WAV file to a home theatre receiver. Errors would cause the receiver to lose sync.

Google has a bunch of links on how to rip a DTS disc to a WAV file - there are also a few sample files out on the net. I would post a sample file for download but I don't have anything public-domain/free that I could post. If somebody has something (even a home-made test file) that would be a great resource to have.

Also I do not understand the objection to trying a blind test. If the difference is audible, indeed "night and day", then it should be equally audible in a blind test. Since the time required to switch between sources is the same, blind or not, I don't see how that makes a difference.

Please note, I am not saying you're wrong - I am offering ways to elucidate, quantify, explain, and ultimately resolve any differences. If you're not willing to go those next steps, then I suggest it's rather unfair to claim that there's a problem.

bossanova808
2005-07-06, 20:54
I've just switched from wired to wireless and done a few blind tests and can't hear a difference - using Rotel pre-amp/amp and Rega Jura speakers.

The amp is a bit older so I'm using RCA outs from the SB2

All files are FLAC.

Andrew L. Weekes
2005-07-06, 23:23
It is very easy to verify bit-perfect output from SB2 either by playing non-PCM material or by recording with a PC.

The only problem with this (from the perspective of audible differences) is that the bit perfect test is in the digital domain, where jitter is almost irrelevant unless gross enough to exceed the SPDIF receiver's jitter limits.

The conversion to analogue is where the problem arises. If for any reason the jitter spectra changes on the SPDIF, between wireless and wired operation, even if 'bit perfect', there will most likely be audible differences.

I'm not saying either party is right here, since I've not yet tried it, but it's easy to think that just because it's bit perfect in the digital domain, it remains so when converted to analogue, which isn't true.

Jitter only matters at the point of domain conversion, from A-D, or D-A, whereupon its effects are totally dominated by the digital receiver's jitter transfer function. Most SPDIF receivers use a single PLL, with a corner >5k, so any jitter below that remains unattenuated.

To measure the effects of jitter (on the analogue output) is quite hard to do, yet the effects are clearly audible.

Andy.

Stric9
2005-07-07, 16:27
I don't own a Squeezebox2 yet but was looking at purchasing one in the near future for streaming music to my bedroom. At the moment I use XBOX Media Center to stream music to my living room and have noticed this same problem with FLAC files that are streamed wirelessly. In my case there is an audible difference between wireless streaming and local playback from the XBOX built in harddrive. I would definately be interested to find some more concrete data as to why this is happening I was hoping the Squeeze Box would have solved this problem but this doesn't appear to be the case.

Also Andrew if you could point me to any good references on the digital jitter problem I would be very interested in reading them.

Stric9
2005-07-07, 16:59
I found the following article which appears to be a good read on jitter...

http://www.digido.com/portal/pmodule_id=11/pmdmode=fullscreen/pageadder_page_id=28/

However i'm still reluctant to say this is the culprit on this issue. From my understanding jitter is a time based issue that occurs when the timing on the transmission side is unstable and the DAC uses this unstable timing as a basis for conversion. I would presume the Squeezebox or XBMC in my case would read the FLAC file into a buffer and then send it via the digital output to the receiver where the DA conversion would take place. If this were the case as long as the buffer was never empty the wireless-ness of the transmission should not contribute to jitter in my opinion.

sleepysurf
2005-07-07, 19:17
Interesting comments, and link! Unfortunately, I haven't had time for more listening tests (and having to work this weekend, won't till late next week). However, I'm hoping somebody else (with more audio and technical know-how than I), can perform some OBJECTIVE measurements in the meantime.

Sean, one other possibility, perhaps??? My SB2 was one of the earliest units that had the grounding issue, and I sent it back for repair. It was promptly fixed, and I might be grasping at straws here, but is it possible the repair could account for what (I think) I heard?

seanadams
2005-07-07, 20:57
I am not going to answer any more questions in this thread until someone is willing to try a blind test. It only takes a few minutes.

There is no logical explanation as to why wired vs wireless should sound different. I could explain all the science behind this, but it's completely irrelevant - just let your EARS tell you. If you claim "night/day" differences then you should have no problem passing the Pepsi challenge. Please give it a try.

NealG
2005-07-08, 00:09
I'll give it a go today.

Aylwin
2005-07-08, 01:12
I am not going to answer any more questions in this thread until someone is willing to try a blind test. It only takes a few minutes.

There is no logical explanation as to why wired vs wireless should sound different.
Couldn't agree more.

MrKegFlex
2005-07-08, 04:38
I am not going to answer any more questions in this thread until someone is willing to try a blind test. It only takes a few minutes.

There is no logical explanation as to why wired vs wireless should sound different. I could explain all the science behind this, but it's completely irrelevant - just let your EARS tell you. If you claim "night/day" differences then you should have no problem passing the Pepsi challenge. Please give it a try.

Just to make sure there is no confusion, I don't believe the "night/day" comparision was used to describe the difference between a wired and wireless connection. It was used in my post to compare the difference between my cd player and a wireless sb2.

In my case, I suspect either a setup problem with the sb2, the sb2 is doing something I'm not aware of, bad lossless files, or possibly my cd player is doing something I am not aware of. Support has been quick to respond and explain that the sb2 is not doing something I am not aware of that would affect the audio, so I'm ruling that out. I have rechecked my sb2 settings and I'm pretty sure I can eliminate that variable now too. So, I'm now looking into how I created my flac/wma lossless files and my cd player specs.

FWIW, in my scenario, I was able to setup a wired/wireless test last night. I did a quick 5 minute test and I couldn't tell a difference between the two. However, I have a friend swinging by this weekend and I will have him take a blind test too to see if he can hear a difference... and I plan to give the test more time than 5 minutes to sample different material.

CardinalFang
2005-07-08, 05:12
Unless data is being lost or corrupted when trasmitted wirelessly, then the data is the same in the buffers, no matter how it got there.

Also unless the wireless side is powered down in wired mode, the power supplies will have the same amount of work to do and assuming that the wireless circuitry does not interfere with the digital output, if it's all kept in the digital domain, then I don't see how ther should be a difference at all. I could perceive of a difference between wired and wireless models though if the PSUs were the same.

If you are using the analogue outputs, then I guess in wired mode there could be a diferent in current being drawn from the PSU, but again, I still don't think there should be a difference.

I have compared the SB2 plus Musical Fidelity X-DAC3 in wireless mode with my Copland CD player and there is a difference, but that's not to say that the SB2 isn't a great transport for digital music. I honestly don't use the CD player anymore, the SB2 is more than good enough for my ears.

It's a shame really, by the time you have enough disposable income to afford some really decent stereo gear, your ears are well past their best...plus having been to one too many Motorhead concerts. I wouldn't trust myself comparing sources - my ears aren't trained to do it. I can compare guitar pickups and tone though, since you are focussing on one instrument and the subtleties of the sound and my ears have become attuned to those differences.

Paul

Andrew L. Weekes
2005-07-08, 05:23
From my understanding jitter is a time based issue that occurs when the timing on the transmission side is unstable and the DAC uses this unstable timing as a basis for conversion.

That is true.

I would presume the Squeezebox or XBMC in my case would read the FLAC file into a buffer and then send it via the digital output to the receiver where the DA conversion would take place. If this were the case as long as the buffer was never empty the wireless-ness of the transmission should not contribute to jitter in my opinion.

What you may have overlooked here is there will be jitter on the transmission interface to the DAC and it is this jitter (and this jitter only) that can cause audible degradation, depending on the DAC's jitter transfer function (i.e. how much jitter on the interface gets to the DAC clock). In the case of a Benchmark DAC1, it's none, for other DAC's it varies a lot, depending upon how well engineered they are in terms of the SPDIF interface, the receiver circuitry, the clock regeneration etc.

Andy.

Andrew L. Weekes
2005-07-08, 05:30
These links make good reading: -

http://www.benchmarkmedia.com/appnotes-d/jittercu.html

lots more here: -

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

and here: -

http://www.digido.com/portal/pmodule_id=11/pmdmode=fullscreen/pageadder_page_id=28
Andy.

NealG
2005-07-08, 13:13
I tried it. Uncompressed wav only. Significant other half got bored after about 6 'switches' I could not tell the difference. Tried it a few times on my own and could not tell the difference!

Stric9
2005-07-08, 13:54
What you may have overlooked here is there will be jitter on the transmission interface to the DAC and it is this jitter (and this jitter only) that can cause audible degradation

I understand that this is the case. My point is that the transmission interface to the DAC is buffer->transmission interface->DAC. In other words the buffer is filled the same way whether it's wireless or wired networking interface and once your in the buffer the networking method shouldn't matter anyomre, so jitter should not be the culprit here unless something really wacky is going on.

I'm glad to see some people have done tests and seen no difference. I'll purchase one for myself and see if I can notice any difference and post my findings.

MrKegFlex
2005-07-09, 20:52
Just to make sure there is no confusion, I don't believe the "night/day" comparision was used to describe the difference between a wired and wireless connection. It was used in my post to compare the difference between my cd player and a wireless sb2.

In my case, I suspect either a setup problem with the sb2, the sb2 is doing something I'm not aware of, bad lossless files, or possibly my cd player is doing something I am not aware of. Support has been quick to respond and explain that the sb2 is not doing something I am not aware of that would affect the audio, so I'm ruling that out. I have rechecked my sb2 settings and I'm pretty sure I can eliminate that variable now too. So, I'm now looking into how I created my flac/wma lossless files and my cd player specs.

FWIW, in my scenario, I was able to setup a wired/wireless test last night. I did a quick 5 minute test and I couldn't tell a difference between the two. However, I have a friend swinging by this weekend and I will have him take a blind test too to see if he can hear a difference... and I plan to give the test more time than 5 minutes to sample different material.

Well... on my hearing differences between my cd player and the sb2 feeding my receiver... I am now convinced I was hearing things that weren't there. Maybe, it's that phantom breakin period? I had a friend over tonight to hear the differences I was talking about and I couldn't even tell a difference when I was doing an A/B test for him. Maybe, I was trying to hear something that wasn't there when I was reviewing the sb2? Not sure but I'm now convinced that my system is performing as expected with the sb2 integrated into it.

I was also able to do more wired vs wireless tests and I could not hear a difference between the two... sober and drunk. ;o) I hope sleepysurf figures out the difference in sound between the wired and wireless in his system. Don't rule out the phantom breakin period when you change something in your system, it can happen... it just happened to me with the sb2 replacing my cd player. :)

sleepysurf
2005-07-10, 11:58
Being housebound with Hurricane Dennis (fortunately little effect in the Tampa area)... I had my wife help me conduct a blinded test. This was done with S/PDIF out to my Yamaha RX-1000, feeding a Sunfire Cinema Grand, and ML Aerius speakers. I also turned off our 2.4 GHz wireless phones.

Picked three "revealing" test tracks, conducted total of 10 trials, randomly switched between Wired vs. Wireless B (five each). I was the only one listening... was correct only 40% of the time!! From my perspective, this proves a) NO significant difference between Wired vs. Wireless, and b) it's easy to be BIASED and believe what you WANT to believe!

I appreciate everybody's input on this thread, and respectfully retract my statement that the difference was like "night and day". (Hmmm, maybe the UV light during daytime listening has an audible effect... <g>).

Andrew L. Weekes
2005-07-10, 13:15
In the interests of science, would you do another test comparing your CD player (assuming you have one) to the SB2 in a blind test.

The results may be interesting!

Andy.

sleepysurf
2005-07-10, 14:18
In the interests of science, would you do another test comparing your CD player (assuming you have one) to the SB2 in a blind test.
That is much more difficult, as the sound levels need to be perfectly matched, and you're really comparing the DAC of the CD player (or outboard DAC) with the DAC of the SB2 (assuming both deliver bit-perfect digital streams, which the SB2 may actually excel at).

pfarrell
2005-07-10, 17:41
On Sun, 2005-07-10 at 13:15 -0700, Andrew L.Weekes wrote:
> In the interests of science, would you do another test comparing your CD
> player (assuming you have one) to the SB2 in a blind test.

The current issue of Stereophile, August 2005 has an editorial
on page 3 that talks about how bad, useless and harmful
blind tests are.

Their website does not yet have the August issue.
The do have a 15+ year old article
http://www.stereophile.com/features/113/
on "Blind Listening"

This is a probably a followup of the
July 2005 issue, where the editor
wrote in his As We See It section:
"Fresh back from the "Great Debate" at HE2005, John Atkinson ponders the
problems of "scientific" listening tests."

In the old article, it says:
" But when you have taken part in a number of these blind tests
and experienced how two amplifiers you know from personal experience to
sound extremely different can still fail to be identified under blind
conditions, then perhaps an alternative hypothesis is called for: that
the very procedure of a blind listening test can <i>conceal</i> small
but real subjective differences. Having taken part in quite a number of
such blind tests, I have become convinced of the truth in this
hypothesis."

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

sleepysurf
2005-07-10, 18:42
Well, either you believe in science, or you don't!

Since high-end audio is all about how it "sounds"... I can't fathom why somebody would nix blind listening tests. Actually, I'd luv to see Reviewers audiograms posted as a sidebar next to all their reviews! Now, THAT would be interesting!

Patrick Dixon
2005-07-11, 00:21
you're really comparing the DAC of the CD player (or outboard DAC) with the DAC of the SB2 (assuming both deliver bit-perfect digital streams, which the SB2 may actually excel at) and (not to be forgotten), the clock jitter performance of the two transports.


Since high-end audio is all about how it "sounds"... I can't fathom why somebody would nix blind listening testsPerhaps because they feel blind listening tests don't accurately predict how music "sounds" when you listen to music, rather than equipment.

When your hypothesis doesn't fit the facts, you have to look closely at your hypothesis - rather than dis the facts!

Fabrice Rossi
2005-07-11, 01:07
Patrick Dixon a écrit :
>>Since high-end audio is all about how it "sounds"... I can't fathom why
>>somebody would nix blind listening tests

> Perhaps because they feel blind listening tests don't accurately predict
> how music "sounds" when you listen to music, rather than equipment.
>
> When your hypothesis doesn't fit the facts, you have to look closely at
> your hypothesis - rather than dis the facts!

Or you can get some facts from the medical and drug design industry and
learn about placebo effect and related things. Your mind is so powerful
that it can actually heal your body not only when you believe your are
given an active drug, but also (in case of single blind tests) when the
nurses and doctors believe your are given an active drug.

Many audiophiles are pissed off because they can't tell the difference
between things that "sound extremely different" under blind test. So
they reject the facts which actually are that those things do not sound
different. No fancy explanation needed here.

Andy gave a very interesting explanation why the standard ABX testing
methodology might 1) rely on short term memory 2) put you under a lot of
stress. This might give an explanation why people fail to recognize
different equipments under the ABX methodology (I'm not completely
convinced, but at least there are some explanations). But, this does not
apply to blind AB tests in which you level match the devices and then do
what you want (listen for one full day to A and then to B, etc.).

The same anti science rant was used by some "psychics". Some of them
refused to perform there tricks under the supervision of a magician or
taped by several high rate video recorder. They claim that the bad vibes
of the magician were disturbing them and other strange things.

Fabrice

PS: by the way, thanks a lot to sleepysurf for reporting his test results.

Patrick Dixon
2005-07-11, 03:31
> When your hypothesis doesn't fit the facts, you have to look closely at
> your hypothesis - rather than dis the facts!

Sorry should have also added:

"or fall back on some (possibly unrelelated) facts, that do fit your hypothesis"

Aylwin
2005-07-11, 05:35
Their website does not yet have the August issue.
The do have a 15+ year old article
http://www.stereophile.com/features/113/
on "Blind Listening"
Very interesting article. The letters are very interesting too. I guess the effectiveness of blind testing depends on how different the sound is between the components tested and also on the person doing the listening. Some people obviously have better trained (or simply more gifted) ears than others.