When and where did you take the survey to find out that "there are people who listen to what happens when changes are made to an audio circuit and there are those who don't"? It's your opinion alright but what is it based on?
Before taking a trip (costs time and money), potential visitors, including skeptics, should find out what's in it for them. How is your listening method set up when comparing DACs for their sound quality? If it's a total bunk, why should anyone waste their time and money? So lets hear it (just like test driving a car before buying).
Are you about to start a DAC business soon?
You can cut through the noise / fog by asking the claimant what evidence the audible difference claim is based on. If you get anything other than direct answer from him, it's a phony claim. In such case, ignoring him and moving on will be the best thing for your time and money.
Look, Jam is a friend and he happens to be both an audio hobbyist and in the audio business. However, he is not in the DAC business and has no plans to be in it. He has plenty of work to do as it is for the next year or two, and by then there should be any number of good, new, well-designed dacs out using AK4499, and also some not using AK4499. If at that time the dac we (mostly me) are working on here is better sounding than other dacs out there, then we will see. But in no case am I going into business. Someone else would have to be found to do that, PCB design and everything else.
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I have no idea what has jam to do with this and why you are even mentioning him in this context. And honestly, I don't really care. As much as I don't care about your past, current and future business plans. I do care about honesty and the technical BS perpretated here, in particular when the perpetrator attempts to wrap it in a pataphysics crust. From this perspective, a vendor forum where the owner has moderating rights is IMO perfectly fine for each and every story about a present or future product.
Example:
To claim that the ancient 7805 regulator is a good choice, better than a modern low noise LDO regulator is an insult to any half competent electronics enthusiast. Either there is no difference (likely) or the LDO is better.
A low noise LDO has to better for some things, not necessarily for everything. I would be fine with using them clocks, digital sections of the dac chip, etc. They don't sound good for analog audio, IME. There may be some reasons for that which are not well documented. Someone pointed me to an old thread which I read for a few pages. There seemed to be some thoughtful discussion about appropriate uses for ADM7150: https://www.diyaudio.com/forums/power-supplies/247643-modern-ultra-low-noise-ldo-adm7150-print.html
...just in case anyone cares to read it.
There is also some old dac documentation translated from Russian in a thread here that explains why use Jung type regulators for AKM dacs:
FS: LynxAudio DAC D60
Here is the translated pdf: https://www.diyaudio.com/forums/att...s-lynxaudio-dac-d60-dac_lynx_d60v1_en_opt-pdf ...2nd page, 2nd paragraph contains the basic finding.
Probably there is more, but it recently occurred to me before seeing the above links that voltage regulator linearity was probably a missing/neglected factor of interest for some audio applications. Not surprising others have thought about such things too.
In addition to the reading material above, some time ago I experimented with an Iancanada ES9038Q2M dac and a Twisted Pear dual LDO AVCC module using ADM7150 family parts. I found that the TP AVCC supply didn't sound as good as the usual opamp circuit we use in way the music dynamics and distortion were rendered. Also found that adding a load resistor (much like described in one of the above links a few pages in) helped, and so did increasing the input voltage from 5v in increments to 7v above which no further improvement in sound quality occurred. At its best, it didn't sound as good as an AD797 non-inverting unity gain buffer following a low noise reference.
All a skeptic has to do is try some things and listen. I used to be much more like the skeptics here until I found some things I wasn't expecting. If you don't bother to look you will never see if you are wrong.
For other claims about audio circuitry that I have always dismissed as impossible or very unlikely, I still am that way. I only believe in what I can directly observe and assess using skilled listening.
Over time Jam has been showing me more things that surprise me, including that trick circuit I used on the AK4499 eval board. I just stuck it there to see what would happen although I was still quite skeptical. When it worked, only then did I start to think about why that might be.
Its been an interesting journey, not what I expected. You would find the same thing too if you would listen first before measuring.
EDIT: Forgot to tell more of the story about NJM7805. For AK4499 eval board, tired substituting a 5v LT1963 regulator for one of the 7805's using the provided banana jacks and jumpers. I figured if the 5v was for the digital part of the output it shouldn't matter what regulator is used, and might not matter much anyway since they were using a 7805. Turned out the LT1963 flattened out the dynamics much like ADM7150 did for ES9038Q2M AVCC. Sounded better with the 7805.
Previously, Jam told me that years ago he and another guy did a comparison of 78xx regulators for audio using samples of all the different brands. NJM78xx won the listening comparison.
Taking the above two things into account, plus previous LDO experience as described, I said to keep the NJM7805 regulators. If you happen to find a better sounding regulator using your eval board, please let me know. On the other hand, if you refuse to try then you get to keep your present beliefs. That important to you?
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I'm not sure if you interpreted everything correctly on that thread. The ADM7150 will slaughter a 7805 in every single conceivable measurement except price (and stability for those who can't read the datasheet or app notes).
The notion that such a regulator is not suitable for analog, but a 7805 is, is ridiculous. They are both series regulators. Do most LDOs use a different pass transistor? Maybe. Does the ADM7150 still soundly beat a 7805 in output Z? Yes.
Maybe I should go tell my colleagues that we should switch to 7805 regulators for our LTC2387-18 ADC driver circuit. The LTC6228 will be more dynamic if we get rid of LT3045 and LT3094 because they are LDOs.
You should let it be known that your assertion is just an opinion, which has no proposed basis in fact, and seems to be contradicted by the millions of high performance analog applications (including Class A Stereophile winning audio gear) which are supplied with LDO regulator ICs from the usual suspects like LT/AD/TI.
Anyway, have a Happy Thanksgiving.
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I sure wouldn't say that to anyone unless I tried it myself first and found it did as you say and that it was a change for the better to my ears. I would then have them listen and compare the two sets of regulators, only then would I tell them what the experiment was about. Obviously, if a data converter is for test and measurement rather than for listening to music then that would likely change things a lot in terms of what is best.
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Thankfully, it's not for audio, so we can define actual requirements.
Purely subjective, maybe. Transient response? I don't really see it. Correct me if I am wrong, but I thought AKM is using this high bandwidth Jung-style regulator with an AD817 and then hanging a large amount of capacitance on the output, ensuring that the transient response is crippled. It's most likely just that they copied what they saw and maybe failed getting AD797 stable.
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Exactly, then recommending to increase the capacitance even more, to improve the LF distortions
.
I'd settle if you could tell what makes an audio applications different from (for example) a space, T&M or medical application. Other than you would always have for audio the universal bludgeon argument "sounds better".
The banana jacks and jumpers on the eval board are there to facilitate testing of any theories
EDIT: Appears we cross posted. Not trying to make arguments, mainly just report observations.
By the way, IME not all LDOs are bad for audio. LT1083 sounds good to me for powering opamps, and in this case the Jung inputs (one LT1083 for all four Jungs).
Also using LT1083 and LM337 (or possibly an upside down LT1083) to power the I/V opamps. However, Jam suggests to try some other regulators before calling that part done.
EDIT: Appears we cross posted. Not trying to make arguments, mainly just report observations.
By the way, IME not all LDOs are bad for audio. LT1083 sounds good to me for powering opamps, and in this case the Jung inputs (one LT1083 for all four Jungs).
Also using LT1083 and LM337 (or possibly an upside down LT1083) to power the I/V opamps. However, Jam suggests to try some other regulators before calling that part done.
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The banana jacks and jumpers on the eval board are there to facilitate testing of any theories
We may have a completely different understanding of "testing". You should use "listening" instead. Or at least "testing by listening".
"Testing" is usually reserved for the process of comparing an experimental result with a specification. Specification which, in your case, doesn't exist.
OT
The term "testing" or "test" is used when evaluating hypothesis.
Insofar, as you routinely take the correctness of your hypothesises (often more just opinions) about possible audible differences for granted and avoid doing/conducting sound listening experiments, it simply aren't complete tests.
So, yes, yours and Mark4's understanding about the correct meaning of the term "testing" is different.
Beside that, I'm quite sure that most (if not every reader) is able to get that Mark4 is reporting his listening impressions.
Instead of bring the same,old fight in every thread like this, wouldn't it be better to offer just constructive tips based on your hypothesises (technical reasons) and to let the OP decide what to do?
If you have to, you could still add a remark that you don't believe in any audible difference occurring when following your recommendations.
The term "testing" or "test" is used when evaluating hypothesis.
Insofar, as you routinely take the correctness of your hypothesises (often more just opinions) about possible audible differences for granted and avoid doing/conducting sound listening experiments, it simply aren't complete tests.
So, yes, yours and Mark4's understanding about the correct meaning of the term "testing" is different.
Beside that, I'm quite sure that most (if not every reader) is able to get that Mark4 is reporting his listening impressions.
Instead of bring the same,old fight in every thread like this, wouldn't it be better to offer just constructive tips based on your hypothesises (technical reasons) and to let the OP decide what to do?
If you have to, you could still add a remark that you don't believe in any audible difference occurring when following your recommendations.