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Optical TOSLINK vs. USB: Which connection is better to connect a DAC? - Page 6

post #76 of 105

< Sounds like jealousy to me evil_smiley.gif

 

I've seen $200+ plastic, I mean polymer cables, and $35 glass ones. I went from a decent quality plastic fiber toslink cable to a similarly-priced glass one, and I noticed a difference. But that was with my highest-quality DAC, the NOS Bel Canto DAC2, which has its own master clock that is optimized for s/pdif: "A local crystal oscillator reference clock drives the DAC directly for minimal jitter."

 

Where I found the Firestone Bravo re-clocker to make a profound difference when used with my balanced Mini-i DAC, on the Bel Canto it had no effect. But what did have a notable effect was switching to the glass cable, that really tightened things up with the BC. So I tried the glass cable with the Mini-i, and it did not make a difference when compared to the cheaper plastic one.

 

The difference in the two results, I believe is the superior "local crystal oscillator reference clock" in the Bel Canto, making it sensitive enough to resolve a difference in the heightened transmission quality of the glass. I've never tried a high-dollar "advanced polymer" toslink cable though, they are likely very nice as well and probably more durable. 

 

Another difference would be that the Mini-i just sounds better when using its coaxial input, rather than its toslink or USB input. So the Bravo is fully utilized with it, providing a re-clocking function along with an s/pdif coaxial converter. The Bel Canto sounded equally good with coaxial and toslink, but better with the glass toslink.

 

These results are all highly system-interdependent; a tweak that improves one component won't automatically have the same result on another one. We have to look at the DAC conversion as a collection of processes to discover where the deficiency may lie.

 

Like Robsix said, the Tx/Rx modules are part of the story as well, just like every other link in the digital-analog conversion chain; they all matter in regards to the final product, the sound that hits our ears.


Edited by grokit - 3/9/11 at 11:17pm
post #77 of 105

 

Quote:
Originally Posted by grokit View Post

< SBut that was with my highest-quality DAC, the NOS Bel Canto DAC2, which has its own master clock that is optimized for s/pdif: "A local crystal oscillator reference clock drives the DAC directly for minimal jitter."

 

Where I found the Firestone Bravo re-clocker to make a profound difference when used with my balanced Mini-i DAC, on the Bel Canto it had no effect.

 


Not very surprising... the Bel Canto DAC2 uses an AD1896 asynchronous sample rate converter (just like the Benchmark DAC1). Any jitter at the input is highly attenuated and transformed into noise (as explained here : http://www.diyaudio.com/forums/digital-source/28814-asynchronous-sample-rate-conversion.html , by an engineer behind such chip's design). A same clock drives the ASRC output and the DAC input.

 

I really like that DAC design btw and I used it as a a starting point for my own DAC. The analog I/V stage is using the very nice sounding ths4130 fully-balanced opamp and a fully DC coupled output stage.

post #78 of 105

ASRC is just upsampling, and I sure as hell don't want my music to pass through a mandatory upsampling pass...all it'll do is increase THD+N and make the sound brighter. It's just a dirty way to get rid of jitter, the poor man's solution..ghetto style. The best Sabre implementations are said to disable its internal ASRC, which many ppl call colored and clinical sounding to the utmost.

 

Glass toslink very much matters if you use cheap gear in realtime, it's been thoroughly discussed in this thread: http://www.head-fi.org/forum/thread/459752/which-is-the-best-optical-cable-under-300/135#post_6599838

 

"I swapped out the 1M Monster cable with the 1M Dayton GOC-3 Glass Toslink cable and viola!

The cymbal smashes became three dimensional with a better sense of space, they were better located in the sound stage and no longer too bright and came to life. The bass surprisingly tightened up even further with better definition."

 

The best sounding cable I found is this one: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=180-951

 

But it doesn't hold a chance against a short coax IME. There are physical reasons as to why glass sounds better than POF:

-lower constringence/optical distortion, much higher OTF/MTF sharpness than plastic

-much higher bandwidth

 

All this allows for a much smoother clock extraction in the end.

post #79 of 105

The Bel Canto DAC2 bright ? Come on... rolleyes.gif  http://www.soundstage.com/revequip/belcanto_dac2.htm (and I globally agree with that review). The Benchmark DAC1 uses the same chip and is more clinical, but it's pretty much down to its analog stage, nothing to do with upsampling.

 

As for an ASRC being "just upsampling", sure, did I ever said the contrary ? Actually, asynchronous sample rate conversion is a more accurate term than the much marketing-abused "upsampling" which has different meanings according to whom you're asking to define it.

 

What are the "best Sabre implementations" which are "said" to disable upsampling so that I don't buy them ?

 

 

post #80 of 105

Well, the holy Benchmark DAC-1 is full of horrid sounding 5532's and 4562's, together w/ ASRC many ppl call it bright and shrill: http://ravenda.wordpress.com/2009/08/14/audiogddac19/

 

"Benchmark DAC1 ($995 ~ harsh, flat out boring)"


That's what crappy dual opamps and ASRC do...just like in the DacMagic(that's fed off a noisy SMPS too), miracles do not occur in the audio world.

 

Apparently, Wavelength's Sabre implementations do disable its internal ASRC: http://www.usbdacs.eu/urzadzenia/Denominator/6.html/

 

Well, it's great that you enjoy upsampling...it's still a dirty way to fix the jitter problem. You can easily measure the THD/THD+N drastic increases when upsampling, using WaveSpectra. Upsampling does sound clearer, but it drastically colors the sound too...and what sounds great for a day/week can become dead boring after a few weeks/months IME. There are smarter ways to fix the jitter problem, that don't rape the waveforms at that.


Edited by leeperry - 3/10/11 at 5:43am
post #81 of 105

The Bel Canto DAC2 has ASRC and is warm sounding. The Benchmark DAC1 has ASRC and is rather cold. From where do you draw the conclusion that the coldness is coming from the ASRC ?

 

"Many people" hear many things. I'm not forced to agreed with them. I've heard the Benchmark and it certainly wasn't harsh. Clean sounding, yes. Harsh, no.

 

Drastic increase in THD ? That's nonsense. Could you please check the THD+N of the Benchmark you were just dismissing ?


Edited by 00940 - 3/10/11 at 6:07am
post #82 of 105

nonsense? that upsampling increases THD+N? you're kidding, right? I did some experiments on the Reclock forum a while ago: http://forum.slysoft.com/showpost.php?p=227530&postcount=4000

 

You can do it too, make a 1kHz/10kHz 44.1kHz test tone wav file using SineGen, upsample it to 192kHz and look at the drastic increase in THD+N in WaveSpectra.

 

Upsampling doesn't come for free...it can somehow "smooth" the waveforms(even though it's highly debated), but it DOES increase distortion and colors the sound. Anyway, we're rather OT at this point and I've got no interest in discussing those matters tbh. We all seem to be happy w/ the gear we own, it's all that matters in the end [:keldun]

post #83 of 105


 

Quote:
Originally Posted by mikemalter View Post




Rob, what are your experiences with optical vs. plastic?
 

 

I have never really sat down and tried to compare the two in any serious way.  I find myself reaching for coaxial cables more just out of habit.

I have many associate that prefer glass if that is what you are asking.
 

 

post #84 of 105
Quote:
Originally Posted by leeperry View Post

...the drastic increase in THD+N....


three one-thousandths of one percent?

drastic?

 

Add to that mind-boggling amount of distortion the fact that I'm listening to it with 60 year old tubes.

There's no hope for guys like me evil_smiley.gif

 

post #85 of 105

If you open the SRC4192 datasheet, you''ll find a nice summary of why I don't loose sleep over ASRC induced distortion. As a remainder, -140db is 0.00001%

 

src4192.GIF

 

Even the best DAC chips will have more distortion, especially as THD goes up with frequency. However, I'll gladly trade the extra distortion against the easier analog filtering I get by upsampling to 96khz. See for example the PCM1794:

 

thd.GIF

post #86 of 105

 

Originally Posted by Justin Uthadude View Post


three one-thousandths of one percent?

drastic?

 

Add to that mind-boggling amount of distortion the fact that I'm listening to it with 60 year old tubes.

There's no hope for guys like me evil_smiley.gif

 


Well, yeah...w/ your 1% THD amp, the audiophile fever will quickly end up in inaudible differences IMHO. POF toslink might not be your biggest problem right now images?q=tbn:ANd9GcQN5YMgogKyHS_Ob3I3K-EI9sXoLDF9zswmXpKUGpxvC-ZuM2sVphaucg

  

Originally Posted by 00940 View Post

 

Even the best DAC chips will have more distortion, especially as THD goes up with frequency. However, I'll gladly trade the extra distortion against the easier analog filtering I get by upsampling to 96khz.

 

Well, who wants to add noise to the incoming signal on purpose? once it's dirty, you can't clean it...

 

Yep, the whole idea behind upsampling is that the oversampling curves will provide a more gentle filtering...each to his own, as usual. Each time I've heard upsampling, it was brighter(due to the increased THD+N) and sounded utterly colored to my ears. Hopefully, in a $1.5K DAC it'll sound amazing \o/


Edited by leeperry - 3/10/11 at 12:20pm
post #87 of 105

@leeperry :You know what's funny ? Somehow we should stay at 44.1Khz and throw DVD-A and SACD to the bin. Distortion figures would be lower than with the high-resolution formats. Higher THD doesn't come from upsampling per se but from the inability of the DACs to cope with high frequency signals as well as with the good old 44.1Khz.

 

@Justin Uthadude: I somehow agree. Chasing the last digits of THD isn't a goal by itself. My favorite amp to this day is still the Audiovalve RKV, not the most neutral ever, and my headphones of choice are the AKG K340, which, I'll admit it, have their coloration. However, I still want a clean source. I've enough trouble with amps and headphones to voice my system as pleases me. I don't want another bottleneck or link to care about.

 

 

post #88 of 105

 

Originally Posted by 00940 View Post

You know what's funny ? Somehow we should stay at 44.1Khz and throw DVD-A and SACD to the bin. Distortion figures would be lower than with the high-resolution formats. Higher THD doesn't come from upsampling per se but from the inability of the DACs to cope with high frequency signals as well as with the good old 44.1Khz.


What's funny is that you compare interpolated upscaled audio data and genuine hi-res files...they have nothing in common whatsoever. One has more genuine informations, the other is filled w/ bogus interpolated data. But hey, you can upsample 44.1@384kHz if you like...I'm sure the experts on the amazing computeraudiophile.com website do exactly that.

 

Many TI DAC's lower their upsampling rate >95.9kHz, but this is not the case w/ AKM chips. Anyway, I'm from Team Oversampling, you're from Team Upsampling...let's just agree to disagree. This is OT discusson anyway [:icon12]

post #89 of 105

We're OT since a long time already and the OP is long gone.

 

You mean the website where they discuss the merits of respective usb cables ? rolleyes.gif

 

It was a jest, because 16 to 24bits saves the day as far as high-resolution formats and THD+N are concerned. However, it is also quite serious. Many professionals, including Dan Lawry (in here: http://www.lavryengineering.com/documents/Sampling_Theory.pdf ), have pointed out that 192khz is completly useless. 24bits/96khz is already overkill. The DAC IC don't care if they receive a file sampled "natively" at 192khz or upsampled. In both cases, they will add more distortion of their own than if they had received files sampled at 96 or 44.1 khz, just have a look at the datasheets.

 

Bogus data is perfectly fine, when the differences in the analog waveform end up under -140db (Benchmark measured distortion due to their use of an ASRC at -135db, http://www.hydrogenaudio.org/forums/lofiversion/index.php/t75505.html ).

post #90 of 105

OK, back OT

I think it still boils down to implementation. Good USB dac beats a dac with a poor s/pdif interface, and vice versa.

Beware, using the better (for you) interface could be another one of those Head-Fi 'sorry about your wallet's as the following excerpt suggests:

 

Another interesting thing about audibility of jitter is it's ability to mask other sibilance in a system. Sometimes, when the jitter is reduced in a system, other component sibilance is now obvious and even more objectionable than the original jitter was. Removing the jitter is the right thing to do however, and then replace the objectionable component. The end result will be much more enjoyable.

Jitter can even be euphonic in nature if it has the right frequency content. Some audiophiles like the effect of even-order harmonics in tubes, and like tubes, jitter distortion can in some systems "smooth" vocals. Again, the right thing to do is reduce the jitter and replace the objectionable components. It is fairly easy to become convinced that reducing jitter is not necessarily a positive step, however this is definitely going down the garden path and will ultimately limit your pursuit of audio nirvana.

Sibilance in a system caused by preamp, amps and other components and cables can also be so high that changes in jitter are not very audible. This is why there is such contention on the web forums about jitter and its importance. What matters in the end is if you are happy with the sound of your system, and whether or not you can hear this distortion.

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Head-Fi.org › Forums › Equipment Forums › Cables, Power, Tweaks, Speakers, Accessories (DBT-Free Forum) › Optical TOSLINK vs. USB: Which connection is better to connect a DAC?