Audio-gd NFB-28
Jun 23, 2014 at 4:23 PM Post #421 of 2,104
Do the NFB-28 and Compass 2 really share the same DAC? The Audio-GD site says that the NFB-28 features a "real balanced DAC" and I see no such mention on the Compass 2 page.

The DAC is exactly the same [ESS9018], the difference is in the balanced amplifier part and that is where it would edge it out - in balanced use only.
 
Jun 23, 2014 at 6:09 PM Post #423 of 2,104
 I don´t think so, since Compass 2 is not full balanced and only "discrete". Yes, Compass 2 uses ESS9018, same as NFB28, this doesn´t
 mean, that they r same.

You spoke to Kingwa in great length like I did? Thought so.
In single ended mode, they're pretty much identical. In DAC only mode, they're pretty much identical. In balanced mode the 28 wins.
Easy as that. The balanced headphone output is the one trick up its sleeve.

In DAC only and single ended use the difference would be slight (if any) not worth the extra price. In those applications, Kingwa recommends the C2 as the better value.
 
Jun 23, 2014 at 11:40 PM Post #424 of 2,104
Kingwa said that the digital volume control (which I know is only for the amp portion) and superior power supply make no difference and that in balanced mode is the only time the NFB-28 is superior? I keep reading about his reputation for modesty...

Maybe I should be looking at getting a separate DAC, then. For some reason I got the idea that the DAC in the 28 was better than the C2.
 
Jun 23, 2014 at 11:49 PM Post #425 of 2,104
Kingwa said that the digital volume control (which I know is only for the amp portion) and superior power supply make no difference and that in balanced mode is the only time the NFB-28 is superior? I keep reading about his reputation for modesty...

Maybe I should be looking at getting a separate DAC, then. For some reason I got the idea that the DAC in the 28 was better than the C2.

 
Isn't that such a rare commodity in the audio market? Maybe Kingwa is the only one. He doesn't make grandiose statements about his products. He doesn't try to sell you the most expensive product he produces with wild claims about how the most expensive thing will produce x, y, and z sound characteristics like you've never heard.
 
I have a lot of respect for that attitude, and it's certainly becoming rarer to find. 
 
Jun 24, 2014 at 5:04 AM Post #427 of 2,104
 
  I don´t think so, since Compass 2 is not full balanced and only "discrete". Yes, Compass 2 uses ESS9018, same as NFB28, this doesn´t
 mean, that they r same.

You spoke to Kingwa in great length like I did? Thought so.
In single ended mode, they're pretty much identical. In DAC only mode, they're pretty much identical. In balanced mode the 28 wins.
Easy as that. The balanced headphone output is the one trick up its sleeve.

In DAC only and single ended use the difference would be slight (if any) not worth the extra price. In those applications, Kingwa recommends the C2 as the better value.

Yes I did, before I bought my NFB28. What Kingwa means "pretty much identical", he just want to say there is noch much difference, if you have asked many questions for different devices, you would understand in most cases he uses these words to say this device is enough, you don´t have to buy better one. :wink:
 
NFB28 is fully balanced DAC and fully balanced Amp in one device, Compass 2 is only discrete DAC/ SE AMP, which uses only one ESS9018 chip, NFB28 uses 2 chips, 2 DAC parts (fully balanced), and has a much better power supply, if you use single ended amp, not like a fully balanced amp, which only use one part for the SE output, both parts of fully balanced DAC are being used, so you definitely get a difference from Compass 2.
 
I have heard both devices connected to NFB6 using SE output, they are not the same, dude.
 
Jun 24, 2014 at 5:33 AM Post #428 of 2,104
  Yes I did, before I bought my NFB28. What Kingwa means "pretty much identical", he just want to say there is noch much difference, if you have asked many questions for different devices, you would understand in most cases he uses these words to say this device is enough, you don´t have to buy better one. :wink:
 
NFB28 is fully balanced DAC and fully balanced Amp in one device, Compass 2 is only discrete DAC/ SE AMP, which uses only one ESS9018 chip, NFB28 uses 2 chips, 2 DAC parts (fully balanced), and has a much better power supply, if you use single ended amp, not like a fully balanced amp, which only use one part for the SE output, both parts of fully balanced DAC are being used, so you definitely get a difference from Compass 2.
 
I have heard both devices connected to NFB6 using SE output, they are not the same, dude.

They're different then, fair enough.
Whatever floats your boat. I went through the same process with him, like you did. I ended up with the C2 as being more suitable for my applications, you did with the NFB28.
Variety is the spice of life 
beerchug.gif

 
One slight misconception in your post - NFB28 has only one DAC chip as well. Check the description and pictures.
If anything, this applies for both: "the ESS 9018 is an 8 channel chip, which uses 4 DACs per channel in stereo mode for lower noise/distortion."
 
Jun 24, 2014 at 5:57 AM Post #429 of 2,104
  They're different then, fair enough.
Whatever floats your boat. I went through the same process with him, like you did. I ended up with the C2 as being more suitable for my applications, you did with the NFB28.
Variety is the spice of life 
beerchug.gif

 
One slight misconception in your post - NFB28 has only one DAC chip as well. Check the description and pictures.
If anything, this applies for both: "the ESS 9018 is an 8 channel chip, which uses 4 DACs per channel in stereo mode for lower noise/distortion."

Yes, you are right, only 1 ESS9018 has been used in the NFB28. 
beerchug.gif

 
Jun 24, 2014 at 2:34 PM Post #431 of 2,104
You can't get better potentiometer than ALPS though. I personally tried both and found zero difference between a quality analogue or digital volume controllers.
 
Jun 24, 2014 at 2:45 PM Post #432 of 2,104
Yes, ALPS is very good potentiometer, but a relay-based volume control is a level above them. Even if you can't hear the difference in their SNR/distortion performance, the difference could easily be heard if you use efficient headphones/IEMs. With my Denon D5000 and original Compass (ALPS pot too), I had to deal with channel imbalance at 8-9 o'clock or so. Can be very annoying, depending on your headphones and listening preferences.
 
Jun 24, 2014 at 5:08 PM Post #433 of 2,104
Oh very sensitive headphones and IEMs!
Yeah, haven't thought about these.
But I did test my compass with the MA900 15ohms and RE-400 and Sony NC headphones and got zero noise... Maybe you need ultra ultra sensitive phones? Or maybe it's improved design.
 
Jun 24, 2014 at 5:28 PM Post #435 of 2,104
Here is an interesting read from official Audio-GD NFB-28 page about volume control:

The I/V conversion volume control without sound degradation

Usually the volume control can be implemented in the DAC + amplifier combo in two methods:

Method 1: The volume control is implemented into the digital stage. The major drawback is that 1 bit of the D/A conversion is lost in every 6DB volume reduction. So, even though the built-in DA chip is 32 bit, in fact, only 16 bit may be left at low volume level.

Method 2: The volume control is implemented in the analog amplifier input stage through a volume pot to reduce the signal level. However, the volume pot affects the sound quality adversely. A low grade volume pot loses the details and creates channels imbalance resulting into soundstage distortion. Even a high grade volume pot inevitably loses the details. Both methods degrade the sound quality.

So, NFB-28 applies the I/V conversion volume control, the volume control is just a variable passive I/V conversion being placed at the ACSS amplifier output, where the output is current signal but not voltage signal. I/V conversion is to change the volume level from the current (I) signal to the voltage (V) signal. (Like R-2R D/A chips output passive I/V conversion) It can keep the signal frequency band flat while not losing any detail. It does not degrade the sound quality in every volume level. In front of the volume control, there are four groups of diamond non-feedback buffer output stages that offer very low output impedance.

Mark Levinson also knows that current volume control has great benefits, so in the volume control of his top grade hi-end preamplifier No.32, he uses many components to change the voltage (V) signal to current signal (I), then through the R-2R network to control the volume, and finally changes back to voltage signal (V) again. NFB-28 simply works in current (I) signal domain, and technically, it is superior to the conventional technology due to less conversion.

The volume control quality is much more important in a real balanced gear. It must guarantee the signals of the four channels are exactly the same to bring out the benefits of a real balanced gear. If the cold signal and hot signal of a balanced gear are not exactly the same, the balanced output will has a large distortion causing the sound quality and performance even much worse than a single end gear. This is a waste of a balanced design and the additional cost.

NFB-28 applies digitally controlled relay-based volume control in 160 steps. It has 80 steps in both high gain and low gain mode to allow users to control the volume level smoothly. NFB-28 has two relay-based volume control boards (totally four channels) through changing the DALE resistors to control the volume to avoid channel imbalance, achieving the best performance and sound quality of the gear.
 

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