Differences in sound: DAC vs. DAC + Pre-amplifier

[barrows]

19 minutes ago, hopkins said:

Why are you questioning my motivation ? 

 

I am not challenging the fact that isolating noisy digital audio is "proper engineering" - please don't misquote me. I am challenging the fact that you are "selling" in most of your posts a given "architecture" based on solutions which are unproven and debated.

I questioned your motivation because I had no idea why you would challenge what is fairly basic, accepted, best practice for implementing digital receivers without citing any other approaches of note.

 

I did not misquote you, any quotes i posted were taken directly from your posts?

 

OK, so experience counts for nothing with you, I must say i do not really get that: say your getting a heart transplant, would you rather have a surgeon who has done the procedure before, or a first timer?

 

I will take a look at the thread you reference.

 

And by the way, i am not "selling" anything here.  I currently have no affiliation with any company which produces any commercial DAC for sale.  My opinions are my own, as the result of my experiences and the experiences of the engineers I have discussed the subject with over the years.

 

I would disagree that isolating USB (as well as ethernet) interfaces is an "unproven" approach.  It is actually well proven by many, many companies making DACs.  In fact, most of the better DACs available use this approach, and if one measures carefully, for things like USB packet noise, for just a single example, one can show in measurements that well engineered isolation reduces noise in a DAC's output.

 

[barrows]

 

@hopkins, are you associated with EC designs?  If so, you probably should reference such in your signature.

 

I took a quick look at their website, and I find it kind of confusing that at first they criticize USB, but then their interface is just a D-D converter form USB to toslink?  Weird way to go if you think USB is problematic in the first place.

 

I have zero interest in anything that has anything to do with Toslink, there are MUCH better optical interfaces available, and even if their interface has incredibly good output, it will be compromised by the cheap Toslink receiver on any DAC (I assume they make something better on their own DAC).

 

Also, interfaces which are sample rate limited are of no interest to me.  I prefer higher rate DSD so all this and R2R PCM specific DACs hold no interest for me as well.  Although if one must use PCM, a really good R2R approach can sound nice.

 

Measurements do not show most of the problems they claim there can be with USB when good isolation is implemented, they just seem to claim such and offer no evidence.  I would expect their optical isolation of USB to work well if they implemented it well, such an approach could be used inside any DAC of course.  And it could be applied to an Ethernet interface as well: i look forward to seeing actual measurements showing that this approach improves on already accepted approaches in wide use.

I do believe ground loops can be a problem with USB: this depends the source used: I prefer a USB source which is floating for the USB output for this very reason: some DACs will be sensitive to this, some will not-certainly with DACs which have non-isolated USB interfaces ground loops can be an issue.  But if the USB source is floating, there is no problem.

[barrows]

22 minutes ago, EvilTed said:

Actually the X1 is NOT a DAC.

It is a network streamer, so it negates the need for Ethernet renderers such as Sonore or SotM.

It has optical network input, so it is comparable to the OpticalRendu from an isolation point of view.

 

Semantics: I would say it is a DAC with an Ethernet input.  Like I said, i am very familiar with the X-1, and I like the way it sounds.  But a DAC cannot compared directly to a Renderer, as the performance of a Renderer has to include whatever DAC and cable it is connected to .

I am glad that you like your preamp!

[barrows]

3 minutes ago, hopkins said:

 

No, I am not associated in any way with ECDesigns. I am a consultant, like you, but in IT - nothing to do with audio.

From the summary you give, I suggest you spend a little more time reading the link I gave you.

Yeah, i read the entire post.  Lots of words, but zero measurements.  Like i said, it might be interesting to use their approach to isolate the Ethernet or USB input in a DAC, and then measure compared to conventional approaches using isolation chips.  I would like to see that comparison.  So far, the measurements I have seen of conventional isolation approaches do not exhibit the large amounts of high frequency noise and poor ground isolation which EC Designs claims.  But if their approach is really that superior in terms of isolation, I am all for it and getting it in a package which can be reasonably implemented to isolate the Ethernet or USB input inside a DAC.  Optocouplers are already used for this by some companies of course, but increasing the distance of the input side to the output side should reduce capacitive coupling, whether this actually results in a meaningful difference needs to be proven.  

[barrows]

4 minutes ago, hopkins said:

As for "sample limited" versus DSD, perhaps you should keep an open mind about that as well, given that you have probably only heard digital with "less than perfect" isolation (to quote you). 

Not gonna happen.  DSD is the superior format for me.  Especially with the ability to oversample with a powerful computer, fully isolated from the audio system (in another part of the home, connected by optical fiber).

I have now heard 4 different types, of discrete, DSD DACs at home, and every one of them had a big advantage over any PCM DAC, including discrete and chip based R2R.  DSD has the advantage of allowing for such a simple, low noise conversion stage, which is still actually linear (unlike R2R).  Everyone of these discrete DSD DACs, while being different in overall performance aspects had a naturalness and ease to their sound quality, that I just do not ever hear from PCM, and that was regardless of the isolation between the USB interface and the DAC, a couple of them I listened to with no isolation at all, and still that natural sound quality prevailed.

I am open minded, but I am not going backwards.  I have tired a lot of things and good sound can be achieved a lot of different ways, but I kept coming back to the discrete DSD converter approach because it offered a sound quality nothing else shared.  Now the trick is to optimize the approach.

 

 

[barrows]

2 hours ago, Summit said:

Technical evidence I don’t know, but one principle I consider to be of great importance is that it’s better to attempt to NOT let the noise “come in” than to clean it up later down streams.

Exactly, and by using Ethernet you keep noise from the server coming in.  Specifically, best practice is to use optical fiber Ethernet.  No matter what extremes one goes to trying to make a server as silent as possible, that server will never be as silent as well designed Renderer.  I suggest, that the better approach, is not bother about making the server silent.  Put it in another part of the home, and do not let its electrical noise to get to the audio system, by sending the music to the audio system over Ethernet (which is isolated by transformers), or even better, with optical fiber Ethernet (which does not pick up and carry electrical noise at all).

The the only noise which gets to the audio system is that generated locally, in the audio system.

 

There is another big advantage to Networked Audio as well:  You can do as much processing in the server as you may want, run room correction, for example, or much more sophisticated oversampling programs like HQPlayer (which can be a big sonic advantage, especially HQPlayer oversampling and a simple DAC which does no additional processing onboard, reducing noise in the DAC even further).  All this processing in the server makes a lot of noise, but by isolating the server away form the audio system, connected by only an optical fiber cable, the noise never gets to the audio system.  

[barrows]

2 hours ago, matthias said:

IMO, there is no evidence at all that the endpoint concept is superior sounding, quite the contrary.

There is no possible technical explanation for why this would be so.  and it is entirely contrary to my, and thousands of others' experience.  No matter what extremes one goes to, a server can never have a s low a noise profile as well designed Renderer connected by optical fiber Ethernet.  The server, by definition, generates a larger noise profile.

I would suggest that the above expressed viewpoint is an outrageous one, not supported by any valid technical theory, and as such would be in opposition to any accepted understanding of how electrical systems, and audio systems actually work.  In order to support such an outrageous claim, I would suggest that a lot more than listening impressions of a few people would be required.

Can you provide any technical theory for this claim?

Can you provide any measurements showing how this approach could possibly make any DAC perform better?

 

[barrows]

4 minutes ago, hopkins said:

Using optical fiber and thinking it actually provides isolation is complete nonsense because you are still putting an ethernet chip inside the DAC. 

 

There are no measurements to back up the fact that this is a superior solution. 

not sure what an "Ethernet Chip" is?  There really is no such thing.

 

Your post misses the point I was making, perhaps I was not clear.

 

I was talking about an Ethernet Renderer connected to a DAC via USB, vs. a Server connected to a DAC via USB.  the point is that the Renderer presents a lower noise profile to the DAC than that of the Server.

[barrows]

5 minutes ago, Summit said:

My own experience has showed me that the sever matters with my uR and I have said it many times. I was one of the first to get a JCAT net board and to use LPS on my switch because of that.  

Indeed, and the working theory for why this is the case is that clock phase noise is the single issue here.  The Jcat NiC has a good clock, hence the improvement.  And of course you are referring to an electrical interface, where noise may propagate, so a low noise NiC is a good idea, and may improve performance.

With an optical fiber interface, general noise from the server does not get to the Renderer, that is just a physical reality.  But there is a theory (and only a theory, at this point unproven) that clock phase noise does travel with the signal.  I am still skeptical, as the implications seem to me to indicate that the Internet itself could not possibly work reliably if this were true...  But, perhaps the measurement system will be developed well enough to actually show that this can happen.  In the mean time, I do advise for using an upstream device with good clocking of the Ethernet data stream.

[barrows]

11 minutes ago, hopkins said:

I quoted you yesterday, and that really summarizes your logic, which is  just guesswork:

No they are not, they are verified through measurements, and correlated with listening tests.

 

BTW, I spent a little time looking for measurements of EC designs DACs.  Given the very high levels of distortion products in the outputs of these DACs, I would not trust that any relevant opinions could be formed by listening tests, of source noise, using these DACs.  Any low level effects caused by source noise would almost certainly be swamped by audible levels of distortion at the DAC's outputs.  I am not surprised that EC Designs does not give any specs for their DACs.

[barrows]

20 minutes ago, bodiebill said:

Don't we all agree that network activity to some degree degrades SQ?

Do you mean other Network activity, separate from the activity of playing the music file?  If one is concerned about such, then I would advise an isolated dedicated LAN for the audio system, this is not hard to implement.  I would suggest testing for such effects in one's own system before bothering though: how about streaming some hi res video to couple of TVs while listening, and then shutting down the rest of the Network and listening again.

If you mean the network activity only associated with playing the music file, I would suggest that optical fiber cable isolates the Renderer and DAC from that.  If we are playing music files from a computer, now matter how we do it, there is always some processor activity associated with the action, this is unavoidable.  So the question becomes, how much processor activity is acceptable (or even audible), and how do we reduce that activity.  Using a Renderer which runs with less than 25 watts of power (one can equate power usage, roughly, to how much noise will be produced) is a good way to reduce computer activity which may effect the DAC to the lowest level possible.

Oversampling in the computer, and using a DAC with no onboard oversampling, is another way to reduce noise inside the DAC, and comes with the side \benefit of being able to apply more sophisticated and accurate oversampling algorithms.

[barrows]

7 minutes ago, Summit said:

f an optical fiber interface would make the digital signal immune to all types of noise

I did not say that, please go back and re-read the posts.

The current theory is that clock phase noise may be able to travel embedded in the signal, although this theory is highly speculative at this point.  Because of this, a good clock handling the Ethernet data stream is recommended for absolute best performance.  Hopefully, at some point, there may be verification of this theory.

General, server borne, electrical noise is not transmitted over optical fiber interfaces.

[barrows]

14 minutes ago, hopkins said:

 

As I said, I am not affiliated to them, and i suggested that you address  your questions and speculations directly with them. I send you a link yesterday to illustrate another point of view on the topic of isolation,  to which you basically replied: optical sucks because DSD is better! 

 

Well, believe it or not, USB ain't that great either.

 

We live in an imperfect "audio" world, with a lot of "unknowns", and i think the quote i gave above illustrates well that point. 

 

 

 

Respectfully, the above illustrates that either you are not actually reading my posts, or you are misreading them in some way:

 

I am not speculating here, at all.  Again, I am referring to things which have been shown in measurements and correlated with listening tests-not speculation.

 

If you prefer to believe in "magical" solutions to audio "problems" which are demonstrated to be non-existent, i am fine with that.  But this is not my approach, and I do not share "magical" beliefs with you.

 

There are not as many "unknowns" as many people seem to like to believe.  Electronics, and audio, are very well understood.  Perhaps not perfectly understood, but very nearly so.  developing audio equipment is a process of engineering, it is science, and it actually adheres to the laws of physics.

[barrows]

4 minutes ago, bodiebill said:

I got better sound when removing the network connection, alas losing my remote access of course.

Interesting, was this with an optical fiber Network connection?  And did you ever try and verify the test with someone else removing the Network connection while you listened, without your knowledge, and were able to accurately discern the exact moment the connection was removed?

 

[barrows]

3 hours ago, bodiebill said:

 

Yes, with optical isolation also, using a fiber NIC in the endpoint. However in the end I changed back the last downstream part with copper ethernet as to my great surprise this clearly sounded better to my ears.

 

 

No, never did that so I cannot disprove placebo 🙂

However I am usually not comparing short term A/B but long term effects by living with the setups for days, being aware of the frequency of goosebumps or at least the amount of joy and involvement.

Sometimes this makes me conclude the opposite of the initial A/B assessment.

For instance if A has a higher level of detail I initially think it is better, but when I notice that I can listen to B much longer and stay involved, I choose B.

It is all very intuitive (sorry) so perhaps hard to replicate for others.

 

For years I had a complete optical network between server and endpoint, and was happy as in my mind optical was almost synonymous to noise isolation. Now I think that was an example of placebo, as when I went back to copper for the last stretch, just to try, I saw had been wrong, at least in terms of perceived SQ.

 

I really do not want to be promoting specific products here, and have tried to avoid doing so.  But, I would suggest that actual Renderers purpose built for audio, do have a technological (not imaginary) advantage in terms of noise versus general commercial computer gear.  Built for audio products generally have much more room in the BOM to spec more expensive components (like many ultra low noise linear regulators) and more sophisticated layouts, with more isolated sections.  For just a single example of what I mean: how many commercial main boards used as a renderer have a dedicated LT 3045 regulator, just a few mms from the USB output for the USB output power leg?

i agree that long term listening is often better for really evaluating a change, although it can be very difficult.  For me, short term comparisons often lead to "ah ha!" moments, where there "might" be a "difference", but the difference in often a sideways one, and not necessarily an improvement.  We humans seem especially subject to interpreting any change as "exciting" and therefore concluding it is better; long term listening seems to even out these first impressions, especially when a wide variety of music is tssted.  I always try and verify any conclusions based on short term A/B style comparisons with long term listening.

[barrows]

51 minutes ago, matthias said:

 

A good example is this one with the Taiko Extreme:

 

https://www.whatsbestforum.com/threads/taiko-audio-sgm-extreme-the-crème-de-la-crème.27433/page-150#post-631854

 

Maybe interesting for @barrows as well. 🙂

 

Matt

What a waste of time that was.  Same old nonsense, with no basis in technical reality and no actual facts, just a listening preference.  I asked for a technical explanation of these claims, and support of measurements, i see none here.

[barrows]

12 minutes ago, matthias said:

@barrows

 

Maybe a more technical explanation here:

 

https://www.whatsbestforum.com/threads/taiko-audio-sgm-extreme-the-crème-de-la-crème.27433/page-99#post-616560

 

Matt

That is not a technical description.  What I mean by a technical description is one which gives an actual technical explanation for why a given approach results in a change in performance.