[Baten]

What I hear is what was recorded, nothing added, nothing lost. perfect phantom-like imaging.

Yeah.. Doubt

 

[439598]

@Zenvota
Not sure what that image is supposed to prove.


Link me to the source of that measurement for the NFB28, I have not found any measurements for it , and yes those levels of THD are easily audible, especially if its odd order. And that does not account for more complex distortions like IMD.
Also I cant speak about NFB28 because I havent heard it, i only heard R2R11 and it was one of the worst things Ive ever heard but to be fair this is an insanely inexpensive discrete amp+ R2R DAC combo.
The point im trying to make is that if an NFB28 was redesigned using feedback (correctly) it would only sound better, based on my own perception of ''transparency'' in gear, but AudioGD want to make there amp more flashy and special so they make it without feedback and then name it after that fact and make a big deal about that fact... it is good marketing, not gonna lie.

You actually brought up an excellent poiint when you talk about switching supplies, poor regulation etc...
This stuff can make an amp sounds like garbage, adding feedback will actually allow the designers to get a garbage amp to measure better... and this is extremely common practice.
And as you clearly pointed out you are making the mistake of blaming feedback for bad sound in these garbage amps.

I have built zero feedback Class A amps to extremely high standards, best possible power supplies and components (based on subjective trial and error testing, not just what stuff people claim are best) they sounded amazing... Then incorporated feedback into them while changing nothing about the base amp and what do think the result was? A better amp. tighter, cleaner, more open. As I mentioned already there very subtle things i preferred when it wasnt using feedback but not even close to enough to not use feedback, and im suspicious it may have just been higher levels of 2nd order distortion that I liked.
I think I am fairly qualified to talk about the differences between using feedback and not using it... not just the differences between 2 vastly different amps, one of which happens to use feedback while the other doesnt.

Also, you should know that transistors themselves use a feedback mechanism to work, feedback is inherent to the transistor itself so you are never going to really have a true ''Zero feedback amp'', it only ever means zero global feedback

 

[Zenvota]

@Zenvota
Not sure what that image is supposed to prove.


Link me to the source of that measurementfor NFB28, I have not found any measurements for it , and yes those levels of THD are easily audible, especially if its odd order. And that does not account for more complex distortions like IMD.
Also I cant speak about NFB28 because I havent heard it, i only heard R2R11 and it was one of the worst things Ive ever heard but to be fair this is an insanely inexpensive discrete amp+ R2R DAC combo.
The point im trying to make is that if an NFB28 was redesigned using feedback (correctly) it would only sound better, based on my own perception of ''transparency'' in gear, but AudioGD want to make there amp more flashy and special so they make it without feedback and then name it after that fact and make a big deal about that fact... it is good marketing, not gonna lie.

You actually brought up an excellent poiint when you talk about switching supplies, poor regulation etc...
This stuff can make an amp sounds like garbage, adding feedback will actually allow the designers to get a garbage amp to measure better... and this is extremely common practice.
And as you clearly pointed out you are making the mistake of blaming feedback for bad sound in these garbage amps.

I have built zero feedback Class A amps to extremely high standards, best possible power supplies and components (based on subjective trial and error testing, not just what stuff people claim are best) they sounded amazing... Then incorporated feedback into them and what do think the result was? A better amp. tighter, cleaner, more open. As I mentioned already there very subtle things i preferred when it wasnt using feedback but not even close to enough to not use feedback, and im suspicious it may have just been higher levels of 2nd order distortion that I liked.
I think I am fairly qualified to talk about the differences between using feedback and not using it... not just on the differences between 2 vastly different amps, one of which happens to use feedback while the other doesnt.

Were any of your non feedback designs kept in current domain? Because thats the point. And using a passive i/v conversion for volume control at the amps output. Hence wire with gain, the d/a chip outputs current signal directly to the amplifier, no operational amplifiers, no i/v conversions until the output

 

[439598]

Were any of your non feedback designs kept in current domain? Because thats the point. And using a passive i/v conversion for volume control at the amps output. Hence wire with gain, the d/a chip outputs current signal directly to the amplifier, no operational amplifiers, no i/v conversions until the output

First off show the measurements of NFB28, or did you just make that up?

We are talking about feedback in headphone amplifiers, not sure what ''keeping things in the current domain'' (seems to be another marketing gimmick of AGD) has got to do with this.

 

[Zenvota]

refering to anything Audio GD as ''wire with gain'', now that is a joke.

Wait a minute, are you telling me 50db feedback loop operational amplifiers with multiple i/v conversions is more wire with gain?

Back to your original post:

the NFB is a ''no feedback'' amp, this is something some audiophiles swear by and think sounds better but any engineer will tell you performs far worse on paper, the NFB will have an order of magnitude greater distortion, probably more noise and also higher output impedance than THX789 or 90% of competing amps which are using feedback.

You can see that you're ignoring the effects of nonfeedback in current signal by saying it performs far worse on paper. Every honest measurement at normal listening conditions for audio-gd components is very good to excellent and consistent between each other.

The output impedance of the audio-gd components is 1-2, the THX789 is 1. worst case. and best case close to zero.

 

[Zenvota]

We are talking about feedback in headphone amplifiers, not sure what ''keeping things in the current domain'' (seems to be another marketing gimmick of AGD) has got to do with this.

lol ok buddy good talk

 

[439598]

Wait a minute, are you telling me 50db feedback loop operational amplifiers with multiple i/v conversions is more wire with gain?

Back to your original post:



You can see that you're ignoring the effects of nonfeedback in current signal by saying it performs far worse on paper. Every honest measurement at normal listening conditions for audio-gd components is very good to excellent and consistent between each other.

The output impedance of the audio-gd components is 1-2, the THX789 is 1. worst case. and best case close to zero.

multiple I/V conversions? proof you dont know what you talking about.
You deflecting the discussion to i/v and current signals, when it started about feedback in headphone amps.

but since you went there, what is more wire with gain? blatantly audible levels of THD and IMD? or practically non existent measurable distortion?

Ok ok, they are running the NFB at high volume which is causing is to distort more...you are free to provide your own ''excellent'' measurements of the NFB at normal levels to try to reinforce your point. There was nothing further from a wire with gain than an R2R11 at normal or low listening levels to my ears, so you can understand the skepticism.

Anyway im not telling you anything except that calling audiogd gear ''bit perfect'' and ''wire gain'' is ridiculous, that has nothing to do with feedback vs NFB, discrete vs chips, DS vs R2R etc. only audiogd gear.

 

[Zenvota]

Fair enough on the i/v conversion I may have had the levinson amps on the brain which do perform multiple iv conversions.

Here's a pcm1704uk dac/amp from 2013:
http://www.changstar.com/www.changstar.com/index.php/topic,1353.0/nowap.html
THD, % | 0.0033
THD + Noise, dB (A) | -84.4d
IMD + Noise, % | 0.0075
Stereo crosstalk, dB | -92.2
IMD at 10 kHz, % | 0.027

https://reference-audio-analyzer.pro/en/report/dac/audiogd-nfb-2-flavor-2.php#gsc.tab=0

Here's they're most recent circuit design:
http://www.audio-gd.com/Pro/dac/AS1/AS1EN.htm

I don't trust anything coming out of a.s/r or s/b..a-f. A/.mi-r is notorious bs and the other one loves a specific. There was another review that I can't find that had video showing the excellent measured performance up until max amplification, aka 9watts

 

[sajunky]

@Zenvota
Also I cant speak about NFB28 because I havent heard it, i only heard R2R11 and it was one of the worst things Ive ever heard but to be fair this is an insanely inexpensive discrete amp+ R2R DAC combo.

Me neither. However I have to point out that what @Zenvota wrote about gound loops should be evaluated carefully and dealt with. I am pretty sure that it was your experience with R2R11, that you didn't. Ground loops were also strong on the ASR reviewer equipment to such levels that R2R11 was triggering autocalibration every 20 seconds. There is a proof for ground loops, it is present on a dashboard FFT. The same happened with an infamous botchered review of TotalDAC and couple different brands.

And finally I also had a strong, devastating influence of a ground loop. Initially my R2R11 was giving very grainy, unpeasant sound, leaving it for a night didn't help. Luckily, (in addtion to fixing of a previous owner mistake) reversing the Euro plug in my laptop PSU broke these things up and after 30 minutes of warming up, my R2R11 started a new life.

I must say, R2R11 is a very good DAC and headphone amp combo. In a proper environment it can sound the same as 3-times more expensive R28. It is my endgame for only $350. R28/R27 have more connectivity and sound options and, most important, a much better protection from external disturbance, but such protection comes at a price.

Your respondent tried to discuss things like FETs, current loop, I/V conversion techniques, the shortest signal path - there are very technical. It comes to the comment about advertising on the A-GD website; take it as a designer's blog that is only understood properly by people with a technical knowledge. Everything is true, but it is a poor marketing. Compare it with marketing of Denafrips by example. Even the most expensive Terminator Plus comes without a buffered output. It makes it very dependent on the pre-amp and for a price is selling it is not acceptable, IHMO. But customers with pockets $6k have very good amps, isn't? Look around, despite of this fact, Denafrips is very popular amoung headfliers.

R2R11 has everything from the SQ point of view, no shortcuts. However it is NOS-only, not prefered mode by everyone and a SQ depends on the external disturbance. If you are clever enough and deal with a problem it can be very rewarding.

 

[Zenvota]

Yeah.. Doubt

Something recently happened that reminded me of this. Kind of off-topic for this thread but w.e. An industry expert, and I mean 20 years + well respected display calibration and home theater services and reviewer, did a "ya doubt" on me on having a 10 year old projector with a 90% bt2020 gamut.



oops, how embarass... While green saturation is short(theres very little if any video content with that saturation of green), red luminance is higher than spec at 27%.

I also get the OLED crowd telling me their 0.2ms sample and hold response is superior to my 0.012ms impulse response(which is superior to crt/plasma if you know). The JVC crowd telling me their 3chip va lcos is comparable in sharpness/resolution/detail/motion to my single 0.95" ti darkchip dmd.

So when someone tries to tell me their mass-produced heavily marketed product has superior av quality to an extremely well designed av component from a smaller company with limited marketing... I don't believe it. And maybe when someone tries detailing technical aspects of av components its best not to regurgitate common false-contradictions(which often support the mass produced heavily marketed product) because you might be dismissive of something youd truly enjoy.

 

[Terozzzz]

"having a 10 year old projector with a 90% bt2020 gamut. " Well the best HDR OLED TVs cant do even 80%. Not Canons top monitor @30.000$ DP-V3120 either what is used in Hollywood movie level of color grading. So what projector can do it? Ill buy one.

 

[Zenvota]

"having a 10 year old projector with a 90% bt2020 gamut. " Well the best HDR OLED TVs cant do even 80%. Not Canons top monitor @30.000$ DP-V3120 either what is used in Hollywood movie level of color grading. So what projector can do it? Ill buy one.

The photos labeled. I have a Sim2 Mico 40 using Luminus Phlatlight PT-120 LEDs.

Also, 10 years ago there was an rgb laser rptv, the Mitsubishi Laservue that could do 100%+


And, several of the new rgb laser ust projectors have a similar gamut coverage. The Samsung Lsp9t, Chiq C8UT, Hisense 100L9.

And at higher prices the dci 3p and 6p rgb laser 3chip dlp projectors like the christies, barco thor, and the Christie Eclipse.

Maybe i should make a projector-fi thread? xD

 

[Audiofiend1]

Hey, can anyone tell me how the NFB-28. 38 with TCXO pairs with an HE6?

 

[JaMo]

Hey, can anyone tell me how the NFB-28. 38 with TCXO pairs with an HE6?

I have them paired and I can say the NFB28.38 is a good mate for the HE6. I run the HE6 balanced and there is no problem to play at high volume levels if You want.
On a daily basis I listen to my workhorse head phones HE500's fed single ended by the 28.38. They are also a good pair.

You are safe with the NFB28.38. I recommend it as a sufficient and well performing dac+amp for the HE6 and for the HE500
/Jan

 

[tumble]

I have an NFB-28 for sale: https://www.ebay.com.au/itm/Audio-g...ne-amplifier-with-remote-control/143879242801