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Audio-GD NFB-12 - Page 133

post #1981 of 2247

The NFB-12 was one of the unit that could not upgrade to the TE8802 usb receiver board, since It has the USB receiver directly on the motherboard. The NFB-15 seems to be an NFB-12 with the new USB receiver.

 

But as you can see from the two pictures, there's more than that going on:

 

NFB12.15.JPGNFB154.JPG

 

Left is 12, right is 15.

 

The most obvious difference is the use of more surface mount components on the 15. Most of the transistor in the amplifier are now surface mounted. They also modified the power supply. It now has bigger capacitors, with the total capacitance going from 0.01 to 0.015 farad. They added a 22 ohm resistor in there. I bet it's used to lower the noise of the power supply.

 

They probably took opportunity to apply a few tweaks to the circuit. As anyone contacted Audio-gd about the differences? If there's a new thread created about it, it would be nice to post the link here.


Edited by KimLaroux - 6/10/12 at 8:00pm
post #1982 of 2247

Go on then KimLaroux, make the thread!

 

It sometimes makes me cringe that someone who creates a thread which will stretch over 150 pages has next to no interest in the product- That would be me!!

 

@brooko

True, I guess it shows how we hear differently. I was never impressed at all with the original nfb12 (and made it clear ages ago in this thread), especially given the overwhelmingly positive reviews it recieved on this thread. Made my jaw drop on how bad it was to tell the truth and it brought to life crazy 'crazy carls' views on how the audio gd sparrow wasn't a real step up from his headphone output on his macbook!!

 

The nfb12 with the adjustable filters was a significant step up

The nfb15 promises to be audibly better than this........I'll probably get it one day, but sorry kingwa, I'm not buying an under developed product. I'll wait for the final thing.

post #1983 of 2247

I'm not interested in buying an NFB-15, so I'll pass.

 

I was never impressed with the NFB-12 either. The only difference between it and my laptop audio-out is a black background and more power.

 

I don't see why they named the new revision NFB-15. It would have made more sens to call it NFB-12.2 or something. I mean, it's not that much different from the NFB-12. Where does it promises to be audibly better?

post #1984 of 2247

Oh right,

 

Asynchronous (if that's how you spell it) usb is a big catch. This would warrant a new name for the nfb12. To loads of people here, it's a big difference

post #1985 of 2247
Quote:
Originally Posted by CantScareMe View Post

The nfb15 promises to be audibly better than this........I'll probably get it one day, but sorry kingwa, I'm not buying an under developed product. I'll wait for the final thing.

 

Totally agree with you on that.  I'd definitely buy another one of the Audio-gd line (especially if it's a value product like the NFB-12), but I'd be a bit more cautious next time - waiting for the product to mature.  If I'd waited a month, I'd have had the switchable filters on the front plate.  As it was, I guess I was lucky getting the filters (by jumper) at all.  I would have been a little P.O'd if I'd bought the first revision with no filter changeability.

post #1986 of 2247

Yea, true say.

 

I was just randomly browsing the CHAOTIC audio gd website when I came across the nfb15 and thought it'd be nice to share it with folk interested in the nfb12.1......... 

 

........anyway.

post #1987 of 2247

This NFB-15 looks interesting. But I doubt it would much different than the NFB-12 soundwise. I think Kingwa just wants all his products to have the TE-8802 usb adaptor. It makes more sense to buy just one adaptor in bulk than buying two different ones in smaller quantities.

post #1988 of 2247

They also released a NFB-16, which is half the size of the NFB-12. They call it portable, but there's no battery in it. It's more of a transportable dac/amp. It's in the same class as the Audinst HUD, AudioEngine D1 and the likes.

 

But I didn't come here to talk about that. I want to know if any of you has any technical information on the gain settings of the NFB-12.

 

Because even low gain is too high, and I often find myself lowering the volume to the point where there's bad channel imbalance. I plan on reverse engineering the gain/volume controls and lower the low gain setting. I realize though that ACSS is not using conventional volume control, and so hacking it would be quite a challenge. So if anyone has any information that would help me doing it, it would be greatly appreciated if you could share it. Thanks. 

post #1989 of 2247

Hmmm....  That is an interesting question. Why don't you e-mail Kinqwa maybe he can direct you in the right direction.

post #1990 of 2247

Well I hadn't thought of that. Asking technical information from a manufacturer and expecting an answer seems like an alien idea. 

 

But it worked! I received an answer, telling me which resistors to change, to what value, and what the result will be.

 

There's 8 2202 surface mount resistors in a line of 16 resistors between the dual DACs and the dual relays. 2202 is 22k 1%. Changing these with 47k resistors will lower the gain by 7dB.

 

Here's the line of resistors in question.

 

Resistors setting up the gain on the Audio-gd NFB-12.

 

The other 8 resistors are 5.6k. They alternate, so there's 22k, 5k6, 22k, 5k6... etc. I'm guessing the 5k6 are for the high gain and the 22k for the low gain. Edit : Just received an email confirming the 5k6 are for the high gain.

 

So now all I need are 8 47k resistors in 1206 package. Changing these will be quite a challenge. biggrin.gif


Edited by KimLaroux - 6/19/12 at 9:20pm
post #1991 of 2247
Quote:
Originally Posted by KimLaroux View Post

Well I hadn't thought of that. Asking technical information from a manufacturer and expecting an answer seems like an alien idea. 

But it worked! I received an answer, telling me which resistors to change, to what value, and what the result will be.

There's 8 2202 surface mount resistors in a line of 16 resistors between the dual DACs and the dual relays. 2202 is 22k 1%. Changing these with 47k resistors will lower the gain by 7dB.

Here's the line of resistors in question.

350x225px-LL-f3bffed7_Gain_resistors.jpeg

The other 8 resistors are 5.6k. They alternate, so there's 22k, 5k6, 22k, 5k6... etc. I'm guessing the 5k6 are for the high gain and the 22k for the low gain. Edit : Just received an email confirming the 5k6 are for the high gain.

So now all I need are 8 47k resistors in 1206 package. Changing these will be quite a challenge. biggrin.gif
Surface mount resistors. . . Ouch.

Good luck!
post #1992 of 2247
Quote:
Originally Posted by Tilpo View Post


Surface mount resistors. . . Ouch.
Good luck!

 

They aren't so bad, it's a 1206 package. They're 3.5 X 1.6 mm, which is barely smaller than a 1/4w trough hole resistor.

 

The problem is to get my hands on replacements. I might end up having to buy a hundred. But hey, at least I'll have enough to match them perfectly. biggrin.gif

post #1993 of 2247
Quote:
Originally Posted by KimLaroux View Post

Quote:
Originally Posted by Tilpo View Post

Surface mount resistors. . . Ouch.

Good luck!

They aren't so bad, it's a 1206 package. They're 3.5 X 1.6 mm, which is barely smaller than a 1/4w trough hole resistor.

The problem is to get my hands on replacements. I might end up having to buy a hundred. But hey, at least I'll have enough to match them perfectly. biggrin.gif
You're bound to have enough, lol.

But then the question is whether your DMM is good enough for 1% matching.
post #1994 of 2247
Quote:
Originally Posted by Tilpo View Post


You're bound to have enough, lol.
But then the question is whether your DMM is good enough for 1% matching.

 

I verified. 1% of 47k is 470 ohms. My DMM has one decimal in the 200K function. This gives me 100 ohms of precision, or 0.2% of 47K.

 

So yeah, I can just buy 5% resistors and hand match them. It should be better than buying 1% resistors and not hand matching them, which I believe is the situation with the stock resistors.

post #1995 of 2247
Quote:
Originally Posted by KimLaroux View Post

Quote:
Originally Posted by Tilpo View Post

You're bound to have enough, lol.

But then the question is whether your DMM is good enough for 1% matching.

I verified. 1% of 47k is 470 ohms. My DMM has one decimal in the 200K function. This gives me 100 ohms of precision, or 0.2% of 47K.

So yeah, I can just buy 5% resistors and hand match them. It should be better than buying 1% resistors and not hand matching them, which I believe is the situation with the stock resistors.
Do note that precision does not equal accuracy. A DMM can give a really precise reading, but not be consistent in it. 1% should be possible, on the other hand.
If you want even more precision, you could try making a circuit on a breadboard and use current measurements instead. You could have two of them in parallel and hook up a steady rail voltage to both sides and measure current. If the current is very close to being the same on both resistors, then they are closely matched.
Let's say your DMM has 0.1% precision in the mA current.

This should be more precise than the measuring resistance directly, but I may be mistaken.
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