Why is SPDIF better than USB?

[Dynobot]

If jitter was ONLY in the time domain and its effects never in the frequency domain then it would not be an issue because it would be inaudible.
 
The whole issue IS jitter timings affecting frequency AFTER the digital signal is converted to analog and affecting the frequency...ie audible character of sound.
 
crap in, bad timing jitter---->da coverter--->crap out, horrible frequency response
 
good signal in no jitter---->da converter--->good signal out, good frequency response
 
One measurement tool on the Jitter side for timing usually measured in ps...
One measurement tool on the frequency
 
Two different tools, one measuring the purity of data going IN the other measuring the purity of frequency coming out.
 
 
Er....something like that

 

[Pricklely Peete]

The biggest myth perpetuated by the those that eschew (anything pro is great) is the misguided maxim that the latest tech is always the best. As far as DAC's are concerned the latest tech still does not surpass what was built nearly 20 years ago (in the audiophile industry, the high end).......think about it. Just about all of the top level dac's still use a topology and a set of IC's that are well over 10 years (or more) old. The only reason sigma delta IC's were developed were to cut manufacturing costs for the core builders. It was a bean counter move...many companies require a min level of profit, that profit drives the R&D department to improve things (if they can get away with it) by producing similar results using less expensive parts. As labor costs climb (in the West) you see the result (literally) compared to the previous 2 decades. Most gear 30 years ago was built to a much higher standard (overbuilt in some cases) but could be had for a reasonable sum. Fast forward to today and you have the same level of build going for outrageous sums. The trickle down effect in terms of whiz bang bullet points rarely equates to "superior sound quality" from the previous high water marks. It is very rare that a real earth shaking breakthrough emerges in the pro or audiophile community. The last great sea change was CD/digital itself (late 70's early 80's)...the second I would say was the solid state revolution. Neither are considered as clearly superior replacements (tubes, vinyl) than the tech they were supposed to better (arguably). I happen to think redbook was a damn good leap but I also feel that vinyl and tubes have a magic that cannot be duplicated (fully).
 
Something to think about....newer is not necessarily better but it usually is cheaper to mass produce (which is why the marketing types hype the new stuff as being slightly better than the old)....the rest of us study this development and do the smart thing (compare it to known benchmarks and judge).
 
Peete.

 

[Dynobot]

I don't know about that....DICE II jitter rejection was not around 20+ years ago.
 
Neither was the famed Sabre Dac ship...
 
Neither was Asynch via Firewire I don't believe...
 
20 years ago Toslink [consumer] and AES/EBU [pro] was the preferred methods of digital transfer.  Now USB [consumer] and perhaps Firewire or AES/EBU [Pro], but in either case I think the technology feeding that Dac chips have improved significantly....even if the chips have not.  But then you are what you eat.
 
 

 

[K3cT]

Quote:

 

Yes, many testimonials seem to confirm that ASRC kills the whole point of using a low jitter transport...but many ppl believe that a mandatory upsampling stage is uncalled for, only degrading and coloring the sound. Most recent DAC chips already include a very capable oversampling stage.

It's not that simple I believe.
 
Here is a thread discussing such issue: http://www.diyaudio.com/forums/digital-source/28814-asynchronous-sample-rate-conversion.html

 

[Pricklely Peete]

BNC has been around for a long time...jitter reduction circuits (I'm somewhat dubious about this tech and the claims made)...just use a DIR9001 receiver chip and forget about the gadgets that for the most part don't drop jitter any lower than a DIR9001 would (using a correctly terminated coax). The Cirrus Logic receivers (8214/8216) run in the 200ps range....Don't get too hung up on jitter numbers as long as you have a decent receiver and a well built transport the result should be quite good (with or without so called jitter reduction circuitry). The variables that contribute to SQ degradation (or improvement) are myriad and it depends on the entire chain being optimized rather than just specific parts of it (although any positive steps forward should be looked at as long as they don;t make ridiculous claims ).
 
The latest Sabre DAC chip is still just a sigma delta design which has the same issues as any other chip of that ilk. The Sabre however is just a better implementation (chiefly the 9018 version that uses 8 parallel DACs internally).
 
There is a reason why ESS did this (to compete directly with designs using 8 pieces of mult bit R2R chips, namely the pcm1704). Does such a DAC outperform the older DAC design ? I doubt it...does it come closer than anything before it ? You bet but this is not the norm and it represents many kicks at that can to get where ESS is now.  Think of all the various generations/iterations of sigma delta designs that have come and gone in the last 15 years (none of which unseat the pcm1704/AD1965/pcm58, etc).
 
All IMO of course.
 
Peete.

 

[Dynobot]

Well I guess if you refuse to believe DICE II or Asynch work to reduce jitter then so be it....
 
As for BNC the Pros only use BNC for clocks as far as I know....
 
Consumers have fallen into the hype surrounding BNC's 75ohm superiority.
 
I guess audio is like a Cafeteria, pick and choose what you want or like and leave the rest.  Some people have a plate full of Asynch USB, others BNC cables, while still others swear it all takes the same and choose regular ol Toslink.   Then there are those who want their USB served up to taste like Coax and feel that is the best.
 
I guess I am in the group that likes to try everything and then pick what I like the best, 75ohm or not, Diced II or not, Asynch'd or not.
 
 
Enjoy

 

[Pricklely Peete]

Why would I want insert an extra device between the CD7 and the RE1 ? Whatever claims these people are making (WRT to jitter reduction devices) the actual level of jitter will likely remain somewhere between 30 and 60ps (if you use a decent BNC or RCA COAX). The lowest possible jitter comes from straight connections via I2S from transport to DAC...the ideal pathway would be as short as possible and terminated at both ends at precisely 75ohms. Once you add in RCA jacks, the the cable itself, the cable makeup, the RCA jacks make up...etc etc...the jitter numbers can climb regardless of DICE II etc...in other words the best connection is the simplest...I2S, BNC, RCA COAX, ASYNC USB, TOSLink and lastly regular USB (best to worst). BNC is the only certified 75 ohm standard and it was originally considered for use by SONY/Phillips but they found out that many folks simply balked when asked about the connection type so the choice was made to mollify the masses which led to the use of RCA jacks (digital output) on the back of CDP's and DAC's (when they emerged later on in the 80's). The consumer was very familiar with RCA jacks but totally perplexed by the BNC type (which was in wide use in the video/broadcast/pro audio industry). Funny how things turn out and not always for the better (from a SQ standpoint which refers back to my original post's thrust in this thread).
 
The simple BNC connection between the CD7/RE1 vastly outperforms any other method of hookup or transport I have used (and that includes computer transports). The CD7 is head and shoulders above any of my other source transports. I would focus less on jitter reduction and pay more attention to analog stage design and the level or refinement that is needed for all the of various power supplies required for a decent sounding DAC. If the design has poor power supply design no amount of circuit tricks or anything else will help the unit sound as good as it could sound (if it had properly designed tightly regulated noise free PSU's). That is the key to considering a DAC..look at the power supply first, second and third. You can sort a lot of wheat from the chaff by knowing what a good PSU looks like and how it is built. It's easier to critique by sight than you think (you do need internal shots of course). I'm always leery of any manufacturer that won;t supply internal pics of thier kit.
 
Peete.

 

[jude]

I've spoken with few people who convinced me they truly understand digital audio component design (not just the individual bits and bobs and their individual specs, but designing the whole component, and what finally outputs from that).  Digital audio component design isn't voodoo, but it is something that seems to me to be far more often misunderstood than understood. I think it's a relative lack of knowledge by many (and I definitely include myself in that bunch) about digital audio design that leads us to seek truisms--and, thus, broad generalizations that aren't necessarily true--so that we can feel more comfortable with all of it. I'm not pointing any specific fingers in this thread, I'm speaking from my own personal experience, and what I've done and believed.
 
A lot of audio gear moves across my desks, and I've had a couple of DACs here that had very ambitious published specs.  One had a published S/N that was very high, yet had substantially more self-noise at the output than a DAC I also had on hand with substantially lower published S/N.  Someone clued me in to reading the specs of the DAC chip that was inside that piece, and comparing those to the published specifications by the component's manufacturer (that is, compare the final DAC component's specs to the specs of the DAC chip within it).  Wouldn't you know it, the manufacturer of the noisier DAC was using the specs from the chip inside of it--the exact same S/N, dynamic range, etc.  The other DAC (the one that was actually quieter at the outputs) was using measurements taken at the outputs.  When comparing the latter's specs with the specs of the DAC chip inside it, I was pleased to see they didn't match.
 
In other words, we can talk about all the little individual pieces that go in--like the DAC chip itself, for example--and forget that there are a lot of things you can screw up fore and aft of the DAC chip.  I've seen jitter measurements (not guesses based on ps measurements of individual pieces, but actual output measurements) where changes in the jitter measured at the outputs were affected by whether or not the components' LED displays were on, off, or dimmed.  You can stick the most chic DAC chip in a box and end up with a sub-par overall piece, as there are so many places before and after it that you can do some decidedly non-chic things, whether intentional or not.
 
Anyway, since y'all are talking about jitter, some of the most layman-friendly reading about jitter I've found were posted here at Head-Fi by Dan Lavry.  In this post (link), I provide some links to interesting comments/discussion from Lavry on the topic.

 

[Dynobot]

Actually its not the amount of jitter in the cable that matters so much as the amount of jitter that the Dac chip sees.  With the DSP1 chip as well as DICE II the chip can see much less jitter than what can be measured in the cable.
 
But for the sake of argument, I agree have as less between the source and the Dac is best, again this is thanks to the new Alien Technology that was not around 20 years ago

 

[Pricklely Peete]

As always Jude you manage to clarify the complexities involved better than I have managed to do it. You are right of course there are so many factors that affect performance it's mind boggling to contemplate them all let alone begin to discuss them without putting everyone to sleep (from techno induced hypoxia).
 
I"ll have a look at that link ...thanks.
 
Peete.

 

[Dynobot]

Yes I agree, thank you for the link

 

[krmathis]

It is better?
Please link us to research or trustful comparisons stating so.

 

[phill1978]

ive heard some really good digtal equipment.
 
with all its faults I cant help but feel vinyl is always infront and digital even at 24bit is a 'a copy of sound'. perhaps that the sound is physically happening in the real world and transmitted is the main reason.
 
it just resonates with me much more. and I could acheive serious music enjoyment from a relatively budget analogue (in source not amp or preamp) setup
 
why mention this? well, jitter however micro it may be may offer a small contribution to a lower percieved SQ, but there are far greater things between heaven and earth than this that cause problems with 'digital', its that very perception of what sound is to our ears that causes the problems.
 
 
perspective is needed.

 

[shaddix]

Yeah I also don't understand why usb DAC doesn't just have a buffer in front of it, even just a tiny one, then no need to worry about jitter at all.

 

[MacedonianHero]

So here are some preliminary thoughts on the USB Thingee (using my Concerto and LCD-2s), the major differences between USB straight into my DLIII (upsampling to 192 Hz) is immediately I can tell the sound stage has opened by about 20%ish and given them more "air" (which I like) and the bass/treble seem more extended. Nice!
 
FYI, I'm using the toslink out (Kimber toslink cable) of the USB Thingee right now to my DAC as my Marantz CD player has the spdif connection already filled. Tomorrow, I'll try switching between toslink and spdif. But a good first impression so far on improving my PC audio over standard USB --> DAC.