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Review and Measurements of Audio-gd NFB-27.38 DAC and Headphone Amplifier

rebbiputzmaker

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Those "advantages" (better compression) in the 90s don't mean jack today when we are talking about a small driver package with fast Internet everyone has.


Thanks for the jab. Let me tell you what that computer expertise tells me: zip decompression is built into Windows. Forcing someone to go hunt around for another decompressor to download and install prior to getting the driver expanded and before you can get the DAC working is bad, bad, practice. There is a thing called "usability" in computer software development. And that is what I am commenting on, not any competition between rar and zip.
Not a jab. lol Just trying to fully understand your comments regarding computing. Maybe I have been doing this too long and I am surprised by what I read at times. Things that I find simple I guess are actually not. I believed you mentioned that a driver uninstaller did not run in Win 10. There are many ways to get around this. I will attach a link. Besides compatibility mode, there are third party uninstallers, and if all else fails manually uninstalling. Which does require being comfortable working in the reg file.

https://www.howtogeek.com/228689/how-to-make-old-programs-work-on-windows-10/
 
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amirm

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Things that I find simple I guess are actually not.
What if I asked you to not use your car's driver door and instead crawl through the back door. Simple enough. Will you do that?

When there is an automatic, no driver install way, anything else that requires otherwise is a demerit.

And remember it is one thing to install drivers from a major company. It is completely another when it comes from a random source in Asia.
 

DonH56

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Magnepan's impedance curves are pretty flat, with a little dip around the crossovers and a falling impedance at HF for the ribbon tweeter models, but phase angles are pretty decent. I have always called them "low, but benign". The main problem is they are nominally 4 ohms and insensitive so take some power if you like them loud (and who doesn't? ;) )
 

Krunok

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Magnepan's impedance curves are pretty flat, with a little dip around the crossovers and a falling impedance at HF for the ribbon tweeter models, but phase angles are pretty decent. I have always called them "low, but benign". The main problem is they are nominally 4 ohms and insensitive so take some power if you like them loud (and who doesn't? ;) )

Sure, but that ZOTL40 amp would not be able to drive them even to "normal" listening levels.
Btw, according to this source DWM bass panel has "2 ohms average impedance below 200Hz".

https://www.stereophile.com/content/gramophone-dreams-5-page-2

Here is my opinion: my Audio Aero Capitol has 50W in class A and would drive Magnepan's or any other speakers without any issue as it has output transformers so it can even be shorted. Its price was app $8000, but I would never buy such amp - I got it as a compensation for some job I have done instead of being payed, so I accepted it as it was better than nothing. As I said, I was really surprised when most of my friends said they prefer its sound to my SS amp but I don't really agree - it sounds nice, but you can actually hear how it colorates, although I have to admit it does that in quite a pleasant way. I do however like very much how it glows in the dark. :)
But the point is these amps are simply not worth that kind of money considering their specs and the way they sound. Unless, of course, you REALLY like the way they sound.. :D
 
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Krunok

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1017_ZOTLfig1.jpg
1017_ZOTLfig1.jpg


Btw, I'm pretty sure that the +-0.9 dB of the non linearity measured here (black line) before adding the Zobel network to the speaker simulator would also be masked by speaker's own non linearity which is typcaly at least +-3dB in that region, so it won't be heard. What could be heard however are distortions coming from the fact that amp ran out of steam when driving speakers with low impedance, and that is exactly why distortion is raising sky high as delivered power is raising.

We seem to often come back to the same things - what we hear vs what we measure. But there is no mystery there: we hear distortion in music as it doesn't sound accurate as it should, and we hear noise, that shouldn't be there. Regarding the distortion, we measure it by measuring harmonic distortion as harmonics added to the signal. We measure intermodulation distortion as non harmonics which were added to the signal. And finally we measure linearity of the system (such as the graph shown above) as it will also cause distortion because complex signal which contains many harmonics will not be processed in a linear fashion as amplitude of some frequencies will be altered which will result in alteration of the complex signal itself = distortion.

Regarding the noise, we measure SNR, although that one is quite complex as it is consisting of white noise, spurs (from various factors, such as power supplies etc), jitter etc. Various noise components can alter signal amplitude, but they can also alter frequency and phase of the signal. Things are, of course, much more complex than this, but let's be clear with the basics - the deviations that we hear always fall into 2 of these categories: distortion and noise, and each of those nice graphs that Armin produces are related to one of these categories.

And here is how it should look like when done properly:

Parasound Halo integrated amp, costing app $2500, so less than half of that fuzzy tube amp.
https://www.stereophile.com/content/parasound-halo-integrated-integrated-amplifier-measurements


 
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DonH56

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Sure, but that ZOTL40 amp would not be able to drive them even to "normal" listening levels.
Btw, according to this source DWM bass panel has "2 ohms average impedance below 200Hz".

https://www.stereophile.com/content/gramophone-dreams-5-page-2

Here is my opinion: my Audio Aero Capitol has 50W in class A and would drive Magnepan's or any other speakers without any issue as it has output transformers so it can even be shorted. Its price was app $8000, but I would never buy such amp - I got it as a compensation for some job I have done instead of being payed, so I accepted it as it was better than nothing. As I said, I was really surprised when most of my friends said they prefer its sound to my SS amp but I don't really agree - it sounds nice, but you can actually hear how it colorates, although I have to admit it does that in quite a pleasant way. I do however like very much how it glows in the dark. :)
But the point is these amps are simply not worth that kind of money considering their specs and the way they sound. Unless, of course, you REALLY like the way they sound.. :D

Sorry, I have not really been following this thread, was just responding to the comment on Maggies in general. The DWM is a special case and is wired in parallel with the center or mains in most applications so drops pretty low, too low for most.

I use cheap Emotiva amps right now so what do I know.
 

Krunok

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I use cheap Emotiva amps right now so what do I know.

Are you saying that knowledge correlates with the price of the amp? :D

Emotiva amps all look very fine to me while being reasonably priced. Which one do you have?
 

Bhargu

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honestly this is not a surprise to me. When I talked to kingwa from AudioGD about ordering their products.... he was very much in tune with audiophile Hype.
I asked him technical questions which he couldn't answer, he then told me that there is a "language barrier". So I then had my chinese friend type of my question in chinese and I sent it to him and he said the same thing in chinese (that he couldn't explain it).
Which actually meant that he didnt know the differences.... I was asking him about the 9038Pro chip being "true balanced" with just one DAC chip vs using dual chips in a mono mode... and he just kept saying that you can just do balanced with one chip if you like. And I asked him the technical difference then vs a single ended and he couldn't tell me what it was.
I asked him what the difference is in terms of components from the NFB-11 to the R2R-11 and the R2R-2, etc considering that the "dac only" unit was twice the price of the DAC+amp "budget" unit.
Once again he couldn't explain the actual technical difference or advantage to spending more than twice the money on only one component.

He said that r2r is for "older audiophiles because they like the sound" and that if I am a "new" audiophile that I will like the Sabre based one instead.

I opted to not spend any money on their products as I didn't get a good feeling from someone who is touting technical terms but cannot explain anything technical.

I am not justifying him, but 9038Pro has better numbers in stereo mode than most other chips in mono mode. Still, that wouldn't make it true-balanced, but it might be possible to build a semi-balanced 9038 device with better characteristics than true balanced, dual-mono setup using other chips.

On an off-topic note: I saw someone asking for true balanced headphones on Massdrop, ie. headphones with 3-pole cables to each ear (with inverted-signal). I am starting to think some people are just taking the "balanced" thing too far. :)
 

Bhargu

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I hope that Melokin DA9.1 measures well. I am in the market for a new DAC and has been intrigued by the 9038Pro for some time - A sabre without the so-called 'Sabre harshness'. The manufacturer specifically mentions the low-noise regulators that they are using and the whole lot of options it has (they seems to have included all the options of the chip itself and about 6 inputs - overkill for me).

Did @amirm measure the DAC out of this (NFB 27.38)? I don't remember noticing that part. I haven't seen many measurements of 9038Pro, but the ones at Archimago's review of Oppo Sonica shows the noise characteristics to be really close to SMSL Idea. This puts a damper on my 'intrigue'. :(
 

gvl

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ES9038Pro is an 8 channel DAC, each channel is actually implemented with 4 DACs internally for the total of 32 DACs per chip, that's plenty for a true balanced design using a single chip. There was some info on diyaudio that single-chip ES9038PRO implementations actually offer better dynamic range than dual chip designs due to the need match chip outputs between channels when using 2x chips.
 

Bhargu

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I thought it was 8 DACs with 4 DAC per channel in stereo mode. Does anyone know how multiple DACs per channel affect the signal?
 

Jimster480

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I thought it was 8 DACs with 4 DAC per channel in stereo mode. Does anyone know how multiple DACs per channel affect the signal?
This is what I thought too when I looked into the technical specifications.
If GVL is talking about internal 1 bit DAC's well he might be right but I don't think there are 32 DAC's inside of the single chip.

But yes in that a true balanced setup typically even has different power for each side, which is part of what makes it "balanced" outside of using a "balanced" connector.
So its a different signal path typically with different power stages for each, but yet if its using one chip, its not possible to actually have balanced circuitry since the signal path will have the same origin in the singular dac chip.
 

gvl

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Points of evolution...

As with "ES9018S", "ES9038PRO" is the same as 8ch DAC, but it has 4 DACs per channel and contains 32 DACs in total. So, if you use "ES9038PRO" in stereo mode, you will have 16 DACs per channel operating in parallel.


I think you're confusing balanced and dual-mono designs. As far as I understand modern DAC chips are balanced out of the box, in that they supply differential output for each channel. RME DAC is balanced, yet it uses a single AKM chip.
 

Frank Dernie

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But surely it is the overall design of the device which is important not which chips are used inside it. The chips themselves have been capable of better linearity and SNR than any other part of a domestic hifi for many years though there are some dodgy implementations. I am sure a well engineered DAC with any of top chips in it will be more linear than a poorly engineered one with whatever is the flavour of the moment chip.
 

Bhargu

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But surely it is the overall design of the device which is important not which chips are used inside it. The chips themselves have been capable of better linearity and SNR than any other part of a domestic hifi for many years though there are some dodgy implementations. I am sure a well engineered DAC with any of top chips in it will be more linear than a poorly engineered one with whatever is the flavour of the moment chip.

True about the implementation. I have read comments about how well built the Pro-Ject S2 Digital is. It even seems to use ES9311Q regulators which are the reference for the ES9038 DAC chips (as per their datasheet). Apart from some issues with sub-standard capacitors, amirm also had good things to say about them. The Melokin DA9.1 also seems to have a well-labelled PCB and clean looking PCB (from their stock images). I hope it is actually a good design and it measures well too.
 

Veri

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True about the implementation. I have read comments about how well built the Pro-Ject S2 Digital is. It even seems to use ES9311Q regulators which are the reference for the ES9038 DAC chips (as per their datasheet). Apart from some issues with sub-standard capacitors, amirm also had good things to say about them. The Melokin DA9.1 also seems to have a well-labelled PCB and clean looking PCB (from their stock images). I hope it is actually a good design and it measures well too.

Looking forward to measurement of the Melokin. It does not seem a well established maker so I somewhat hope it is made surprisingly well rather than the opposite.
 

Nihilion

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Is it not a little suspicious that the device in question clearly isn't an NFB-27? The quoted price of the device and the image correspond to the Audio-GD Master-9, which doesn't have a DAC in it. What the hell is going on here?
 

Nihilion

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Not surprised. This DAC probably is not defective. From my experience Audio GD stuff in general is pretty bad. Most of the DAC's I have heard from this company have audible differences that can be picked out. I usually cannot pick apart DAC's. The worst was a dac using NOS 1704 chips that had a combination of rolled off upper FR and distortion.
DACs. Have we forgotten how to pluralize words? The plural of DAC is DACs, not "DAC's". I mean, did you eat "meatball's" today? Did you take the "dog's" for a walk?
 
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amirm

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Is it not a little suspicious that the device in question clearly isn't an NFB-27? The quoted price of the device and the image correspond to the Audio-GD Master-9, which doesn't have a DAC in it. What the hell is going on here?
What do you mean? I have email communication between the unit's owner and Kingwa at Audio-gd repeatedly referring to this unit as NFB 27.38. You are saying the owner doesn't know what he has bought and the seller doesn't know what he sold to him?
 
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