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Review and Measurements of Audio-gd NFB2 192 DAC

SIY

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If you want subjective reviews there's tons of websites such as HeadFi that you might wanna check.

Unfortunately, none of them do true subjective reviews (ears-only). And most, if not all, are highly beholden to commercial interests and cannot be trusted to review things neutrally.
 

tktran303

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There is no doubt this audio-Gd unit inserts an extra 20-30dB of harmonic and intermodulation “special effects”, compared to better measuring units.

I call them special effects, because at these low levels around -70dB they interact with headphone or loudspeaker drive units, which on their own also have their distortion spectrum around those levels.

I think the language and tone we use can be a little combative. Distortion on a scope or visual measurement may look “frightening” but audibly it is not always perceived as “distortion”. It is perceived as the character of the complete system.

Remember these DACs don’t connect directly to the cochlear nerve in our ear. They connect to a preamp, amp, headphone or speaker driver, then through air and finally our pinnae/ear/cranium and torso. All which affect the perceived sound.

Do you want evidence?

Exhibit A: A 11” woofer with 4V applied (2W into 8 ohms)
41B50333-02D8-4D15-9895-670FCD79690F.png


Reference: Hificompass.com

https://hificompass.com/en/speakers/measurements/accuton/accuton-s280-6-283n

If you think that looks bad, it’s all relative.
It’s actually state of the art, one of the best 11” woofers available, as far as electrodynamic speakers are concerned.

Here’s a “frightening distortion spectrum” of a 5.5” midwoofer:
AE918C13-EAA6-4ECE-9462-B4D4A431C443.png


Reference: Hificompass
https://hificompass.com/en/speakers/measurements/scan-speak/scanspeak-15w8530k00

This little driver is the famous Scan-Speak Revelator, considered by many as one of the best 5.5” midwoofers available. And in fact mild variants are used commercial speakers, like a certain US$10K bookshelf speaker, made by manufacturer Wilson A, or W. Audio.


What’s my point?

I’m not defending this audio-Gd unit, or apologising for it.

But I’m also not calling people who like it as tone-deaf, audiophools or idiots.

At -70 to -80dB THD down, these units definitely impart their own character or special effects into your signal chain. Whether you like it, or not, is personal preference.

I prefer the other DAC, from the other Chinese manufacturer. The one with the SINAD of 120dB.
 
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Sal1950

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So to you people that hear it sounds better are all crazy. And they don't care the bad specs.
But nobody on ASR is curious to test if they enjoy it.
That's not honest.
If my interest was in buying a high performance auto and I read a review that showed Auto X only made 35 HP, couldn't go over 40 mph and the brakes faded badly, why would I be interested in taking it for a demo ride? To find out the knobs on the radio have a luxury feel? LOL
 

typericey

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Based on previous reviews, I've always had a hypothesis that the Pink Panther used is a clue/spoiler on how the review will pan out. This review confirms it.
 
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amirm

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Exhibit A: A 11” woofer with 4V applied (2W into 8 ohms)
The largest market for Audio-gd is headphones, not regular system with speakers. They are "desktop" products as indicated by lack of remote control for example.

Headphones can hugely reduce background noise and can be quite revealing.
 

rando

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I just knew the review following best measuring device yet would be fun.

Not sure how exciting this place will be when multiple devices exceed measurement capability into excellence. Well, a couple iFi's buzzing around a pile of Schitt might get some cheap laughs. :facepalm:

Seriously though, is there a contingency plan?
 

tktran303

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The largest market for Audio-gd is headphones, not regular system with speakers. They are "desktop" products as indicated by lack of remote control for example.

Headphones can hugely reduce background noise and can be quite revealing.

Show me a headphone driver with -80dB SINAD...
 
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amirm

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Show me a headphone driver with -80dB SINAD...
Show me a trustworthy distortion measurement for headphones....

And listening tests that show inaudibility due to headphone limitation.
 
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amirm

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tktran303

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SIY

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Something called an Audio Precison

https://www.innerfidelity.com/content/headphone-measurment-proceedures-introduction-and-equipment

You must be new to acoustic measurements. Not Tyll

Don’t shoot the messenger...

The mikes used in the AECM206 fixture I've used for headphone measurement and review have distortion well below 0.1% up to 120 dB SPL. I have measured headphone distortion below 0.02% at 85 dB SPL, so the fixture's distortion must be well below that. Toys like the miniDSP fixture can't do this reliably.
 

Duckeenie

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So to you people that hear it sounds better are all crazy. And they don't care the bad specs.
But nobody on ASR is curious to test if they enjoy it.
That's not honest.

I think that's called confirmation bias, something we all suffer from.
 
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amirm

amirm

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Something called an Audio Precison
Not worried about his electronics. That, we know is great. The worry is about his measurement mic. He is using the Head Acoustics HMSII.3. This is the spec for that: https://www.head-acoustics.com/downloads/eng/hms_II/D1230_HMS_II_3_e.pdf

And 2nd harmonic alone versus frequency:

1560575805086.png


As you see, SINAD is as low as 28 dB at 50 Hz. And only climbs up to 65 dB or so. A perfect headphone would measure like the above graph.

ITU-T P.58 by the way is highly permissive in this regard as you can tell from above graph:

1560575998345.png


These fixtures are designed for other characteristics than pure distortion measurements. The requirement for low distortion is to make sure it doesn't interfere with other measurements.
 
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amirm

amirm

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He is also using the G.R.A.S 12aa mic pre-amp. I can't even find a distortion rating/measurement for that in their spec sheet. Again, they think these are used for acoustic measurements, not distortion.
 

tktran303

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amirm,

So you are asserting that mics have more self distortion that headphone drivers or loudspeaker drivers? And thus are not suitable for measuring distortion?

I don’t where to start...
 
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amirm

amirm

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amirm,

So you are asserting that mics have more self distortion that headphone drivers or loudspeaker drivers? And thus are not suitable for measuring distortion?
The ones as you referenced, yes. I know the operator is not skilled in such, nor is the measurement gear. We can get some relative data but nothing absolute as to compare with the same for electronics.
 
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