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Audio-gd Master 7 Singularity Review (DAC)

AudioSceptic

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I'm not a tech expert but as I understand, the PCM1704 is DAC chip of the "R-2R", sometime called "ladder DAC", variety. These DACs use a different decoding method than the now-prevalent "delta-sigma" variety. Many audiophiles and pundits consider the R-2R DACs to have a nice sound, mainly smoother, more "analog" in sound.

The PCM1704 is now out of production as are many formerly available R-2Rs hence a maker has to be lucky, (let's say), to find a supply.
Thanks. Yes, I get that the PCM1704 is R2R, but it's still an IC which I can't even see in the photo. Here's the spec sheet <https://bit.ly/3C4FPaN>

Edit: looking again, are there 4, 2 each side near the top?

Edit2: I followed a link and missed that it went to 1794, not 1704. Still that was 2003, revised 2006!
 
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PO3c

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You might just like the sound of distortion.
Definitely a DAC that's voiced for a certain sound (distortion).
Yes, that was my thinking when I purchased my M7 with all discrete transistor circuits ;)

My dual setup where I could change between two DAC's from my amp's remote I had the idea not all music needed the coloration. But several month down the road I found that metall/rock/blues and simpler accustic singer/songwriter all benefitted from the M7 in my setup with ATC speakers.

Now it would be nice if one could figure out/agree on how to measure what are perceived as pleasant distortion in hifi products and create a chart similar to the SINAD table.


Thanks. Yes, I get that the PCM1704 is R2R, but it's still an IC which I can't even see in the photo. Here's the spec sheet <https://bit.ly/3C4FPaN>

Edit: looking again, are there 4, 2 each side near the top?
Total of 8 pcs
1631275192710.png


Edit: My understanding they are two in parallel with true balanced design. That might explain why the RCA measure so different from balanced line out?
 
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AudioSceptic

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Yes, that was my thinking when I purchased my M7 with all discrete transistor circuits ;)

My dual setup where I could change between two DAC's from my amp's remote I had the idea not all music needed the coloration. But several month down the road I found that metall/rock/blues and simpler accustic singer/songwriter all benefitted from the M7 in my setup with ATC speakers.

Now it would be nice if one could figure out/agree on how to measure what are perceived as pleasant distortion in hifi products and create a chart similar to the SINAD table.



Total of 8 pcs
View attachment 152468

Edit: My understanding they are two in parallel with true balanced design. That might explain why the RCA measure so different from balanced line out?
Gotcha. So, 4 per channel, plus huge amount of other components, and we get this result? There are much easier and cheaper ways to get such poor measured performance!
 

PO3c

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There are much easier and cheaper ways to get such poor measured performance!
I don't disagree giving we understand what parameter to adjust to give it pleasant sound. For instance a multitude of class A transistor stages produce very different distortion and harmonic content than a single op-amp set up to create similar amount of total distortion.

This blended with inconsistency from old R2R DAC chips I'm sure create a unique sound signature and 'color'. And that is the main purpose for the Master 7 series, to color the sound. Thus rendering them completely useless as measuring devices.

Going through some correspondence with Audio-GD I found the M7 Singularety (M7S) use identical audio boards but have a diffrent digital PCB than my older M7 2015 revision. Same firmware for the FPGA though.
 

sarumbear

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…inconsistency from old R2R DAC chips...
Can you explain what are/were those inconsistencies?

PCM1704 data sheet show THD+N of 0.0008% which is -102dB SINAD. @amirm measured 20dB less on balanced and 50dB less on unbalanced outputs.
 

Ruben G. Remus

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I guess the design philosophy of audio-gd is "The whole is ALWAYS greater than the sum of its parts", so they stuff their designs with as many parts as possible.

You must grant them at least this DAC is likely to sound DIFFERENT (not better) than the competition.
 

Labjr

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If you're gonna spend $2,500 on a multibit DAC, you're probably better off with a Schiit Yggdrasil. You can return it if you don't like it. Probably, have better resale value if you sell it down the road. Has a five year warranty. And you'll definitely get better, faster service if you do have a problem.
 

DSJR

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And while some measurements looks like a 12$ dongle its overall sound quality do not compare to the same dongle. Most listener in this price range are usually adult enough to trust his ears to figure out if they like the overall sound or not.

How do you know an Apple dongle (£7 in the UK) 'sounds' worse than a $3000 dac? I'm going to challenge that statement when the eyes (and facilities needed) are taken from the comparison. This is the whole point really. I FIRMLY believe now that digital audio tech has been a done deal for along time, the main advances today being in doing it at least as well for far less money (I'm looking at Topping and Schiit as best known perhaps, no offence to others doing a great job for not much money). The Apple dongle has sweet FA inside (possibly stuffed on both sides of its tiny circuit board perhaps) and I'm frankly stunned how competent it is and how good it sounds as line source as well as moderate volume level headphone amp...

As for trusting one's ears, do leave off, PLEASE :D Our ears are crap really, they get worse in sensitivity and high frequency extension with each passing decade of age and that's not even taking into account the mind behind them interpreting said hearing... One can be so easily fooled (been there and done it so many times I'm sorry if you disagree).
 
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Lupin

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Has a five year warranty. And you'll definitely get better, faster service if you do have a problem.
Audio-GD offers 10 years ;)
Can say what you want about Audio-GD but the service is very good if you buy from Magna Hifi.
 

Lupin

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In case it was not clear.. I do not defend the brand. I wouldn't trust Audio-GD itself to handle any RMA/DOA request decently.
I do however state that Magna Hifi offers great service for a "dubious" brand.
 

AudioSceptic

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I guess the design philosophy of audio-gd is "The whole is ALWAYS greater than the sum of its parts", so they stuff their designs with as many parts as possible.

You must grant them at least this DAC is likely to sound DIFFERENT (not better) than the competition.
Possibly, but you are paying $$$ for that difference!
 

AudioSceptic

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How do you know an Apple dongle (£7 in the UK) 'sounds' worse than a $3000 dac? I'm going to challenge that statement when the eyes (and facilities needed) are taken from the comparison. This is the whole point really. I FIRMLY believe now that digital audio tech has been a done deal for along time, the main advances today being in doing it at least as well for far less money (I'm looking at Topping and Schiit as best known perhaps, no offence to others doing a great job for not much money). The Apple dongle has sweet FA inside (possibly stuffed on both sides of its tiny circuit board perhaps) and I'm frankly stunned how competent it is and how good it sounds as line source as well as moderate volume level headphone amp...

As for trusting one's ears, do leave off, PLEASE :D Our ears are crap really, they get worse in sensitivity and high frequency extension with each passing decade of age and that's not even taking into account the mind behind them interpreting said hearing... One can be so easily fooled (been there and done it so many times I'm sorry if you disagree).
£9 surely? So much worse value than £7! ;-) But the way to look at it is: just think what's inside a smartphone. Tiny stuff and yet so powerful. Same with things like the Amazon Fire Stick and Roku Streaming Stick.

Otherwise, I agree 99% (allowing 1% distortion!).
 

TCD333

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Can you explain what are/were those inconsistencies?

PCM1704 data sheet show THD+N of 0.0008% which is -102dB SINAD. @amirm measured 20dB less on balanced and 50dB less on unbalanced outputs.
As I stated above (somewhere) the A-GD M7 DAC utilizes a discrete, zero feedback I-V and OP stage. This will be the source of the added distortion. If you want a nice musical 'analog' type sound, these can give it. I've designed and built plenty, I know what they do (compared to say opamps).
You can lower the distortion quite a bit from what has been measured here if you understand how to make them more linear... but I guess most people here would say 'why not just use opamps' ...... but then you could say 'why not use a $3 D-S DAC chip instead of the 1704... and so on.
Most people here are just not going to get any DAC that is like the M7 - even a well designed one won't make much sense because you will be able to get better measured performance for a lot less money.
 

AudioSceptic

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IMO, you're better off starting with a DAC that has close to perfect measurements because it shows that the designer is competent. These days any harmonic distortion profile can be added using DSP, software or other means. Bob Carver proved it could be done with amplifiers, 35 year ago.

https://www.stereophile.com/content/carver-challenge
Yes, I remember that. I'd guess an expert engineer such as John Yang could mimic any of the "audiophile" junk DACs if he could be bothered. Hey, it could be added as "golden ear mode".
 

TCD333

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IMO, you're better off starting with a DAC that has close to perfect measurements because it shows that the designer is competent. These days any harmonic distortion profile can be added using DSP, software or other means. Bob Carver proved it could be done with amplifiers, 35 year ago.
WRT adding distortion - yes, like a 'plugin' used in Protools (recording software). I've been waiting for this to happen in home HiFi but so far
doesn't seem to have.
TCD
 

AudioSceptic

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WRT adding distortion - yes, like a 'plugin' used in Protools (recording software). I've been waiting for this to happen in home HiFi but so far
doesn't seem to have.
TCD
Is this why some obsessives indulge in opamp "rolling"? Trying to add just the right amount of distortion?
 

sarumbear

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As I stated above (somewhere) the A-GD M7 DAC utilizes a discrete, zero feedback I-V and OP stage. This will be the source of the added distortion.
My question was to your following comment. You have not answered what are the inconsistencies about the DAC chips. You have instead commented about the custom circuitry around the chips.
…inconsistency from old R2R DAC chips...
 
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