Review and Measurements of Audio-gd NFB28.28 DAC and Headphone Amp

[andreasmaaan]

I didn’t have to hear the difference between them, when the D50 was in the rig it’s a typical ESS presentation. It’s very similar or too close to the OPPO 105, except that the 105 is “airy” audiphile speak! The M51 is much nicer and easier to the ear. And that’s level match! When the D50 is hooked up to the power amp, it’s the same presentation all the way cranked up! The OPPO 105 just gets “airy” and not in a good way.

Are these shootouts done blind?

 

[Addicted to music]

On the “other” forum,

Are these shootouts done blind?

Nah, no need, when you listen to the rig that long......

I only do blind test if I struggle to differentiate so I can rule one out!

 

[andreasmaaan]

On the “other” forum,


Nah, no need, when you listen to the rig that long......

I only do blind test if I struggle to differentiate so I can rule one out!

Ok, well I remain sceptical (same grain of salt I apply to my own impressions of the Ref 7 / M51)

 

[andreasmaaan]

@Addicted to music would you be up for doing a blind, level-matched shootout between the M51 and the D50? We have measurements available for both (of course not from the same source, but still...). So it would be interesting to see if you can discern a difference between them under controlled conditions

 

[Veri]

Still hoping for the M51 to be measured on here by amir, too =)

 

[SIY]

Are these shootouts done blind?

His description reads almost perfectly like a description of a non-level-matched comparison.

Level-matching is tedious and requires instrumentation, so this most basic of all controls is almost always skipped with the usual handwaves of, "Oh we're experienced, we listened extensively, that can't bias us..." So this doesn't even reach the point where doing the tests double-blind can validate them.

 

[andreasmaaan]

His description reads almost perfectly like a description of a non-level-matched comparison.

Level-matching is tedious and requires instrumentation, so this most basic of all controls is almost always skipped with the usual handwaves of, "Oh we're experienced, we listened extensively, that can't bias us..." So this doesn't even reach the point where doing the tests double-blind can validate them.

Of course I agree with you

 

[Addicted to music]

@Addicted to music would you be up for doing a blind, level-matched shootout between the M51 and the D50? We have measurements available for both (of course not from the same source, but still...). So it would be interesting to see if you can discern a difference between them under controlled conditions

Question for a question,

Would you need a leveled blind test to tell between the Audio Gd ref 7 to a M51?

Would you need a blind test between a $2 9 v transistor radio and a $2k rig? Level match to tell the difference?
Playing the same track....

Buttt, on the other hand, if you tell me you can hear the difference in fancy cables..... now we’re talking, level matched blind test bring it on!

 

[andreasmaaan]

Question for a question,

Would you need a leveled blind test to tell between the Audio Gd ref 7 to a M51?

I'm not sure. I suspect not given measurements of Audio-GD DACs suggest they invariably produce audible levels of distortion, but I wouldn't presume this with a huge amount of confidence

I take it you're not interested in trying, however?

EDIT: ah, I misread your question! I think the better question would be: do I need a sighted non-level-matched test to tell the difference, surely?

 

[SIY]

Question for a question,

Would you need a leveled blind test to tell between the Audio Gd ref 7 to a M51?

Would you need a blind test between a $2 9 v transistor radio and a $2k rig? Level match to tell the difference?
Playing the same track....

Those are two very different questions. Re: the latter, there are gross frequency response and polar pattern differences. The former... not so much. So that excuse won't be rescued by a terrible analogy.

 

[bunkbail]

1.8V vs 2V is a difference of almost a decibel which is definitely enough to make one sound better than the other.

Qutest is the one that outputs at 2V, ~1 dB louder over the ADI 2 should make it sound better but @VintageFlanker said he preferred the ADI 2.

 

[Blumlein 88]

I think most people are confused about "tube sound." It is not like this is something that you can test for with a toggle switch. They buy a tube product with completely different characteristics, like it for whatever reason (due to improper testing), and then assign advantage to a product having "tube sound."

I have yet to find a high-distortion product -- tube or solid state -- do anything for me. I just hear the distortions that take away from the fidelity of music source. Yet all of these products are praised for having a positive tube sound. The difference for me is that I do controlled side-by-side testing and there, it becomes clear with careful listening, you just hear the impact of distortion. Or it is not audible.

Any "warmth" would have to come from rolling off the high-frequencies which a tube amp with high output impedance can impact.

Anyway, the jury is out on whether there is any merit here on making designs with such high levels of distortion.

It would be some trouble, but on product like this could you take an impulse response and make it available? You can use those in foobar and listen via other gear to hear what it sounds like. The RME ADC would be good enough to measure with a sweep via REW.

 

[Blumlein 88]

No blind test but A/B comparaison. Almost level matched. Qutest set to 2V and RME set to Ref Level +7db at 0db which, according to RME correspond to 1,8V. To my hear, I could not say one unit was louder than the other. They do sound different, however. RME has flat frequency response and I'm sure Qutest has little tweaks in high mids and treble which make it sound more detailed and extended but also brighter and harsher.

See this is a mistake where so many mislead themselves. Not picking on you personally.

Close to level matched misleads. Matched by ear still leaves enough difference it is audible. It sounds like a quality difference. You will have set yourself up to actually here something that's not there. It's crucial to get levels matched within 1%. Even sighted many perceived differences vanish.

 

[Blumlein 88]

Question for a question,

Would you need a leveled blind test to tell between the Audio Gd ref 7 to a M51?

Would you need a blind test between a $2 9 v transistor radio and a $2k rig? Level match to tell the difference?
Playing the same track....

Buttt, on the other hand, if you tell me you can hear the difference in fancy cables..... now we’re talking, level matched blind test bring it on!

Too easy to match levels do might as well do it. Otherwise you hear something without matched levels you still won't know till you match levels.

 

[amirm]

Even with gross differences such as in speakers, blind testing is required and provides more accurate results. So all tests need to be blind regardless.

 

[Krunok]

Any "warmth" would have to come from rolling off the high-frequencies which a tube amp with high output impedance can impact.

And that is exactly the only thing what I can notice when switching between my tube amp and my SS amp. As I have them both on switch connected to the same speakers it's easy to do comparison once the levels are matched.

The other thing I notice is that tube amp looks much better in the dark.

 

[Thomas savage]

And that is exactly the only thing what I can notice when switching between my tube amp and my SS amp. As I have them both on switch connected to the same speakers it's easy to do comparison once the levels are matched.

The other thing I notice is that tube amp looks much better in the dark.

Just be sure to let the tubes throughly cool down before you do any ‘experimenting ‘.

 

[Krunok]

Just be sure to let the tubes throughly cool down before you do any ‘experimenting ‘.

I see your logic - as they are contained in glass bottles it only makes sense to cool them, just like beer, right?

 

[Thomas savage]

I see your logic - as they are contained in glass bottles it only makes sense to cool them, just like beer, right?

Well you just don’t want to burn ya arse...

Beer temperature depends on the beer , I’m going to Prague next April I digress.

 

[Krunok]

Well you just don’t want to burn ya arse...

Beer temperature depends on the beer , I’m going to Prague next April I digress.

I always thought beer temperature depends on the fridge, but I don't want to end up with my pants over my head again for opposing the Mod.

Pretty good beer there. Not like your ale, but still very good. The food is also good, unlike your food.