[mmerrill99]

Is anybody seriously going to try to maintain that a distortion which is non-harmonically related @ -50dB isn't going to be audible?

Of course it is, but in this case what caused it also caused the regular IMD test to bomb. I'm saying find me a phenomenon where it doesn't.

I believe you are grossly exaggerating in the bolded text - according to what Stoddard wrote, this was not the case. But continue on, regardless!

 

[charleski]

Yes, you are right, I should have gone back to the post instead of relying on my obviously bad memory - I mixed up this bit at the end of his post with what came before "That’s why we still listen. And measure. And come up with new measurements. And listen again."

But I still ask you what is your list of tests that you would use to "prove" that a DAc was transparent?

 
I doubt I could discriminate between two DACs that both had a flat frequency response +/- 0.1dB, 0.0dB of linearity error and THD and IMD measures below 0.01%. Any competent design should far surpass this, particularly in terms of THD and IMD. The only thing that would disprove the two DACs sounded different would be to do a double-blind listening test, but given that there blind tests like this one that can't distinguish a $2k DAC from an ALC889 I wouldn't hold out much hope.
 

No that was not the IMD measured - that was the result of their multitone test
"What? We ran through our multitone test (it’s easy to do digital multitones on a Stanford as well, not sure about other analyzers) and the low-frequency numbers went bonkers. As in, there was a broad range of non-harmonically related distortion components from 10-90 Hz, at a fairly high level (-50dB or so). -50dB is potentially audible. And it was up nearly 90dB from the baseline measurement."

The multitone test is an IMD test, it's just not the standard SMPTE RP120-1994 variant. There's some debate as to the best frequencies and ratios to use for IMD, and you may well see its value vary across the audio spectrum, just as THD measures vary between 20-20kHz. Using more than two tones just makes it harder to separate the intermodulation components from the harmonic ones.

 

[RRod]

I believe you are grossly exaggerating in the bolded text - according to what Stoddard wrote, this was not the case. But continue on, regardless!

 
Believe what you want. I read that whole thing as "an alarm went off and we investigated further." A yellow alert, if you will. But yes, obviously you think this is the start of a revolution and I'm like "meh", so we clearly see things differently.

 

[RRod]

   
The next questions are:
 
3. How well does this correlate with audible differences?  To Stoddard's credit, he doesn't claim a strong correlation
 
4. How much do other SD ADCs exhibit this?  Is this characteristic of the breed or just the Perfect DAC test subject?
 
And yet if you look at the IMD for the Schiit Gungnir DS vs MB, you see:
 
Gungnir
 
IMD: <0.002%, CCIR
 
Gungnir Multibit
 
IMD: <0.004%, CCIR
 
Okay, so the SD DAC actually has lower IMD...
 
So Stoddard might have found something, or it might be a red herring.  To Schiit's credit, Stoddard isn't claiming strong proof.
 
Seems pretty inconclusive at this point.

 
Seems like I always read about SD having better linearity, which would seem to imply better distortion specs for a given wad of cash (anyone have any math on that?). I guess the question is how this particular DAC messed it up.

 

[cjl]

So you missed that he used a multitone test & found the problem in this "non-standard" measurement - do you still want the flawed pseudo-scientific DBT "proof" or did you want him to set up a large scale, rigorous & carefully administered blind test that has some semblance of scientific rigour?

For those interested Stoddards post is here

And the relevant section is at the bottom
So, tell me your list of tests that should be used to characterise a DAC & "prove" that it is "audibly transparent"

Ahh, that one. I had remembered something else (not sure what though). In that case, I'm not really sure what you're trying to point at - multi tone IMD is definitely a relevant measurement for a DAC - all I see there is that a DAC that measured poorly also sounded poor.

 

[mmerrill99]

Yes, you are right, I should have gone back to the post instead of relying on my obviously bad memory - I mixed up this bit at the end of his post with what came before "That’s why we still listen. And measure. And come up with new measurements. And listen again."


But I still ask you what is your list of tests that you would use to "prove" that a DAc was transparent?

I doubt I could discriminate between two DACs that both had a flat frequency response +/- 0.1dB, 0.0dB of linearity error and THD and IMD measures below 0.01%. Any competent design should far surpass this, particularly in terms of THD and IMD. The only thing that would disprove the two DACs sounded different would be to do a double-blind listening test, but given that there blind tests like this one that can't distinguish a $2k DAC from an ALC889 I wouldn't hold out much hope.

You are seriously going to cite that as a DBT test of worth? Come again!

No that was not the IMD measured - that was the result of their multitone test

"What? We ran through our multitone test (it’s easy to do digital multitones on a Stanford as well, not sure about other analyzers) and the low-frequency numbers went bonkers. As in, there was a broad range of non-harmonically related distortion components from 10-90 Hz, at a fairly high level (-50dB or so). -50dB is potentially audible. And it was up nearly 90dB from the baseline measurement."

The multitone test is an IMD test, it's just not the standard SMPTE RP120-1994 variant. There's some debate as to the best frequencies and ratios to use for IMD, and you may well see its value vary across the audio spectrum, just as THD measures vary between 20-20kHz. Using more than two tones just makes it harder to separate the intermodulation components from the harmonic ones.

Semantics - I was waiting for this! IMD = multitone, yea right!!
Of course it makes it harder to do & it also stresses the device in ways that a two tone test doesn't but continue on, regardless.
Yes you will find multitone tests on many analysers but how many manufacturers of audio DACs post multitone test results in their datasheets?
We see them in the datasheets of industrial DACs with SFDR (spurious free dynamic range) results but few audio DACs

 

[watchnerd]

 
 
The multitone test is an IMD test, it's just not the standard SMPTE RP120-1994 variant. There's some debate as to the best frequencies and ratios to use for IMD, and you may well see its value vary across the audio spectrum, just as THD measures vary between 20-20kHz. Using more than two tones just makes it harder to separate the intermodulation components from the harmonic ones.

 
Right.
 
And we know IMD correlates highly with audibility because it's more harmonically discordant.
 
So finding out a multi-tone test also might correlate with subjectively audible differences is not far-fetched.
 
But nor is it shocking or ground-breaking.

 

[watchnerd]

   
Seems like I always read about SD having better linearity, which would seem to imply better distortion specs for a given wad of cash (anyone have any math on that?). I guess the question is how this particular DAC messed it up.

 
Or how did it come to be so highly praised, and make it to market, with such bad IMD?

 

[XenHeadFi]

 
Or how did it come to be so highly praised, and make it to market, with such bad IMD?

THD is at 0.005% on Gumby vs. 0.002% for DS. Still inaudible amounts, either way.
 
Moffat says that Gumby is better at time domain, waveform (original samples), and other things that I cannot remember at the moment. Time Domain could be the DAC, considering the recommended usage of the chips. Waveform is probably due to the filter, which seems to lead to the question of the filter being independent of the DAC. AtomicBob may have measurements that may shed light on time domain, but waveform seems like a black-box right now.

 

[watchnerd]

You are seriously going to cite that as a DBT test of worth? Come again!
Semantics - I was waiting for this! IMD = multitone, yea right!!
Of course it makes it harder to do & it also stresses the device in ways that a two tone test doesn't but continue on, regardless.
Yes you will find multitone tests on many analysers but how many manufacturers of audio DACs post multitone test results in their datasheets?
We see them in the datasheets of industrial DACs with SFDR (spurious free dynamic range) results but few audio DACs

 
I can't tell what you're advocating...
 
If your point is that a multi-tone test might be more revealing of IMD than the standard IMD test, and that this might show up as being correlated with audible differences, okay.  Stoddard hypothesis it might be true.  Doesn't sound bat**** crazy to me, either.
 
If it can be shown to be persistent and true (where true means highly correlated with DBT)  of most SD DACs, that would be very interesting.

 

[watchnerd]

  THD is at 0.005% on Gumby vs. 0.002% for DS. Still inaudible amounts, either way.
 

 
When I said "How did it come to market", I was referring to the Super DAC, which was much higher.

 

[XenHeadFi]

   
When I said "How did it come to market", I was referring to the Super DAC, which was much higher.

How can "Super" DACs have bad measurements? Have you seen the inside of Lampizator4 DAC?

 

[watchnerd]

  How can "Super" DACs have bad measurements? Have you seen the inside of Lampizator4 DAC?

 
LOL.
 
What do they charge for that hot mess?

 

[Guidostrunk]

$4200 to $5200 :blink:

LOL.

What do they charge for that hot mess?

 

[watchnerd]

$4200 to $5200

 
GTFO!
 
Damn...you would think for that money they could invest in some better PCBs and a pick-and-place machine.