[Kingwa]

In the ACSS circuits, there are no any global feedback, no any feedback  at every  single stage .
Its components all are the current mirrors, the input signal and output in every stages all work in current field, without voltage and current converte.

 

 

[Kingwa]

If without any lowpast filters, the ACSS circuits can working flat at 1HZ to 700KHZ  , and the quadrate waves test , the output signal can same as the input signal .
Some other circuits also can working flat at this field even wider, but the output quadrate waves can't as the input.

 

[Tilpo]

Then what do you think is the cause of the early high frequency roll-off?

 

[Kingwa]

Higher than 20KHz, there are nothings in the normal PCM format music file,except noise.
In the NFB12 with digital filter setting, users can setting 20-20K Hz at -0DB.
Please check this thread earlier post, there are some price more than 50 X times cost gears have worst roll off.
Even setting the NFB12 have 20 to 20K Hz at 0DB roll off, don't expect its sound better than costly but wrost roll off gears.

 

[scannon18]

Does audio GD have a return policy? It would be great if I could try it out, IMO there is no measurement for sound quality more accurate than listening to the gear with our own flawed ears. Classify me as a "subjectivist."

 

[tme110]

Even if there is a return policy it would still be cheaper to just buy something from the used forum and then resell it vise sending it back to China.

 

[scannon18]

Damn forgot about the massive shipping charges. I guess I'll just wait for ODA/ODAC from JDS Labs

 

[palermo]

 
Quote:

I have not confused anything.
All test was done with 96kHz sample rate data, which means they should all be able to reproduce up to 48kHz sound.
But when the data goes from NFB-12's USB receiver, the reproduction is not correct. Other digital interface such as RME's babyface or even Audio-GD's own Digital Interface got 96kHz data to the DAC correctly.
It clear from the FR plot. Both babyface and digital interface to NFB12's DAC reproduced quite flat FR to about 30kHz, then roll off to 48kHz, it's okay since there is LPF(low pass filter) working.
At 48kHz sound, it's about -9dB roll-off, actually, NFB-12's LPF's roll-off is about -6dB, but my recorder card has it's own roll-off too, so I got about -9dB here.
 
BUT!!!!! From NFB-12's USB receiver, the roll-off (it's actually CUTOFF, but RMAA smoothed it, can't disable it) start around 22kHz, the sound is virtally none from 24kHz onward.
 

I agree with mr. killkli. should be no difference between the three graph. 
the implementation USB receiver using TE7022l perhaps not so good. 
this time to consider xmos in all dac audio-gd product 

 
 

 

[malaLamicka]

My new NFB-12.1 just arrive. Its my first headphone amplifier.
 
  
 
 
I'm curious how will it play with my good old Koss UR/30. But somehow I guess it not by best match for this amp.
Any suggestion for properly headphones for this amp? 
 

 

[Tilpo]

My new NFB-12.1 just arrive. Its my first headphone amplifier.
 
  
 
 
I'm curious how will it play with my good old Koss UR/30. But somehow I guess it not by best match for this amp.
Any suggestion for properly headphones for this amp? 
 

It has a fair bit of power, so most headphones will be driven properly on it.

Depending on your budget there are quite a few options available. I personally have tried it with the HD 650, and I can tell that it's a good combination.
I think it would be wiser to ask the same question in the Headphone recommendations thread, they will be sure to point you in the right direction. Do mention a budget, though!

 

[satwilson]

Quote:

It has a fair bit of power, so most headphones will be driven properly on it.
Depending on your budget there are quite a few options available. I personally have tried it with the HD 650, and I can tell that it's a good combination.
I think it would be wiser to ask the same question in the Headphone recommendations thread, they will be sure to point you in the right direction. Do mention a budget, though!

What would be the better source upgrade for me? (Cavalli CTH or Audio-gd NFB-12)  Check this out, post #7, satwilson
 
 

 

[satwilson]

Quote:

You didn't get to my point.
ALL THREE LINE ARE THE TESTING RESULT FROM NFB12
Just the digital sources are different.
 
1. My computer -> Audio-GD Digital Interface Coax-out -> NFB-12(Coax)
2. My computer -> RME babyface Optical-out  -> NFB-12(Optical)
3. My computer -> NFB-12(USB)
 
Using a 24bits/96kHz test file.
 
If the signal was correctly sent from the source to the DAC, all three line should be the same with minor jitter noise, but NOTHING should be different in frequency response.
It's the same with both Audio-GD Digital Interface/RME babyface Optical-out. BUT my NFB12's USB ALTERED the frequency response. THe high is not simply roll off, It's kind of "CUT" off.
Which means from the USB receiver chip to DAC, there is something LOST.
It's not about sound signature, it's about design flaw or unit flaw.
 
KINGWA, your response is still not even touched my point.

You may indeed have a technical point, but in the real world of how this unit sounds to humans Kingwa has answered your concerns, you are being stubborn. In the real world your concerns have no relevance in how this sounds. And your inference that you have discovered some kind of "flaw" in his design, what are your credentials VS his?

 

[scannon18]

You may indeed have a technical point, but in the real world of how this unit sounds to humans Kingwa has answered your concerns, you are being stubborn. In the real world your concerns have no relevance in how this sounds. And your inference that you have discovered some kind of "flaw" in his design, what are your credentials VS his?

I don't know, all things considered it is still a little fishy, and I'm not quite satisfied with Kingwa's response. Who cares if more expensive gear has worse roll off? What is the cause of the nfb12s roll off and why does it only affect USB?

 

[palermo]

Quote:

I don't know, all things considered it is still a little fishy, and I'm not quite satisfied with Kingwa's response. Who cares if more expensive gear has worse roll off? What is the cause of the nfb12s roll off and why does it only affect USB?

still no answer, no explanation.  
 
 

 

[scannon18]

Quote:

still no answer, no explanation.  
 
 

It's not that it particularly bothers me.  A good sounding amp is a good sounding amp.  I don't plan on buying it because the word "warm" scares me away, which is unfortunate because only through listening to it myself could I know if it is too "warm" for my tastes.
 
The HF cutoff is more a nagging interest than anything else.  A curiosity.