Return-to-zero shift register FIRDAC

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MarcelvdG

Member
Joined 2003
Markw4 said:
"As far as I'm concerned, the only thing that is flawed about it is the stuff Mark wrote."

https://www.diyaudio.com/community/threads/return-to-zero-shift-register-firdac.379406/post-7427735

What did you mean by "it" if not the dac. Did you mean my report of the sound of the filter board was the "it" that was flawed?
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I meant that the stuff you wrote was flawed. That referred to your hypotheses about differential circuits. Apologies for the unclear phrasing.

Markw4 said:
It should be music you know intimately, that you always use for test. Its not just the music either. Ideally you need to prepare yourself by clearing you mind. Stop thinking while you're listening. Just listen to everything at once in as much detail as your brain can take in.
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That would be Vivaldi's Nisi Dominus played by Le Banquet Celeste and some DIY recordings of the mixed chorus Rumours then. I've never been any good at clearing my mind.

Markw4 said:
Ran out of editing time. Something I forgot to say is about the DUT. Before starting to listen, its important to let the DUT up warm up and stabilize thoroughly. Overnight is usually good, if you can do it. Clocks can take longer. Some things may need to burn in for days or longer before fully stable (e.g. electrolytics in the sound path). When I am doing these kinds of tests, I try to leave the DUT running 24 hours a day, just turn down the volume for silence. If I have to power a DUT down to make a change, the clocks typically remain powered up.
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That's not going to happen. Some of my power supplies are not safe enough to leave them turned on overnight. (I normally never leave audio equipment on overnight because it's a waste of energy, but I could make an exception for this test if it were safe.)
 
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B

bohrok2610

Member
Joined 2005
Markw4 said:
Ah, but the spectral analysis FFTs look perfectly the same. No difference at all.
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Not really as phase would tell the difference. Most FFT SW is able to show phase as well. Anyhow this is not about FFT but your failing to understand why the files sound different.
Markw4 said:
Yet there are people over there who believe FFTs tell all.
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This site is not ASR. If you have issues with ASR, make your complaint there.
 
M

Markw4

Member
Joined 2016
Marcel,
Then please try to do your best. Maybe let it warm up for a few hours during the day? If you listen SE with some kind of passive filter, versus listen to the filter board as designed, versus slowing the common mode attenuation opamp (we could call them A, B ,C conditions), do you hear any difference in low level musical details, and or do you hear other differences that you can describe in musical and or perceptual terms (just not engineering terms)?
 
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Hans Polak

Member
Joined 2005
Gentlemen,

It’s Mark’s abundant time and money he is investing and whatever he finds is up to him.
When we do not like or doubt his judgements, well that’s what it is, it won’t change anything.

So, could we now please let Mark continue with the Firdac experiments, because the current discussion leads to nowhere and maybe you will find some of his steps worthwile despite all.

Hans
 
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Markw4

Member
Joined 2016
To explore the purpose a little more (if there is one), Acko has expressed a possible interest in making a DSD dac. He knows about Marcel's dac and about Andrea's dac. Marcel's is considerably lower cost to make. Question then arises what do you get for your money? How much money/complexity for how much listening satisfaction of picky audiophiles? How many dacs might people want, given a particular price/subjective-performance point?

What I have found out so far is pretty basic: If you surround Marcel's dac with good supporting circuitry/shielding then it can perform its best. If you modify Marcel's dac to be technically more like Andrea's dac, then it starts to sound more like Andrea's dac.

Next line of inquiry might be, is it possible to retain what is good about the sound of Marcel's dac, while at the same time improving whatever may not be as subjectively good about its sound? If it is possible, how much would it cost?

Right now I am in a bit of quandary. The X5R caps are doing something good, and also something bad. First question, is the good a psychoacoustic consequence of the bad? IOW, is the X5R cap distortion somehow creating an illusion of more space and openness? If the answer is yes, then for me at least we may be at a dead end. It would mean we can't preserve what is good while fixing the bad, at least we can't do it directly. To move forward, a solution needs to be found to solve the problem or else the problem must be reformulated. Maybe its okay to have less space and less openness if the distortion is lower? For some people that would probably be a satisfactory solution. For other people it would be unacceptable.
 
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rfbrw

Member
Joined 2001
Markw4 said:
Which raises the more fundamental question: is it supposed to be more like applied research or like basic research?
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I think calling it research might be stretching things a little. It seems much simpler than that. Shorn of the chaff it boils down to this -
Turning the FIRDAC into something that pleases Markw4. Which I suppose is the ultimate aim of the exercise.
 
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rfbrw

Member
Joined 2001
Markw4 said:
Actually, no. There are other people listening here too. I already told you about pro hi end audio designer guy. I changed the caps back to X5R to satisfy him, not me. I don't like the distortion. Was that not clear?
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Until now there have been positive comments about the FIRDAC. You could have simply commented on the dac and moved on whether your comments were positive or negative. The moment you started to change the design you changed the parameters. You are the one making the changes and you are making those changes based on your listening. That you don't like what you consider distortion is ultimately about you and your preferences but that isn't a problem. That you seem to see yourself as a universal reference might be.
 
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rfbrw

Member
Joined 2001
Markw4 said:
Comment: I hear what my friend above hears, and he hears what I hear. That has been confirmed. So what's going on? IMHO it has to do with preference. Restored to its original state as it is now, the dac has space, soundstage width and depth. But the sound is grungy and grating. Like sandpaper on my ears. I don't like it.

OTOH, the way I had the dac before reversion to original was very precise and well on its way to being very clean and dynamic sounding. But the illusion of space was much diminished as compared to its present state. I like that clean sound better. So do some other people I know who have heard it. To my friend in the quote above, the sound I like is inferior. The space has collapsed and is no longer good sounding.

Ideally we could find a way to satisfy both of us, but its not yet clear to me if that's possible. Part of the answer has to depend on the original recording and how it was digitized. If there were problems there then there may be no way to make reproduction sound a way that is satisfying to everyone.
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Surely, that someone hears what you hear and thinks what you prefer is inferior must cause you to pause for thought ?
 
M

Markw4

Member
Joined 2016
rfbrw said:
Surely, that someone hears what you hear and thinks what you prefer is inferior must cause you to pause for thought ?
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Yes. I think about it a lot. Also think about the guy that heard the Purify demo FM effect just as easily as the AM effect. Obviously, different people hear differently. Their brains process sound somewhat differently. The evidence for that is IMHO overwhelming. However, there are likely be groups of people with different distributions of preferences. An analogy might be that off the shelf clothes and shoes are made to fit so-called average people, although some people say they get a better fit from certain brands. Getting back to sound, is there a so-called average listener who can't hear things a few other listener's can hear? Well, the answer appears to be yes, at least in some cases. Another question might be, can an average, so-called naive listener improve their recognition skills (can they by training and practice rewire their brain a little to hear more)? At least in some cases, again IMHO, it looks like there is ample evidence the answer is, yes. What it all seems to come down to is that human auditory perception is much more complicated than was once believed. However, it doesn't appear to be random. Its not, anything goes. It only has to be good enough for survival, not necessarily better. So it isn't always better. That said, from inside conscious awareness it always seems like objective perception of reality. ...Which it never really is.

EDIT: There is one other thing I said before that some people seemed to have missed. I said pro hi end audio designer guy and I hear the same things, but we have different preferences. What I didn't say about us both hearing the same things was if I meant we both have average aural perception. In some ways I don't think we are average. We are fairly closely matched, but not exactly. We also both have a history of professional/expert experience/training that has taken place over many years. That's all.
 
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