I need a very good fet line preamp circuit for wm8741 dac.

[gaetan8888]

Hello

I need a very good fet line preamp circuit for wm8741 dac. The WM8741 have a voltage balance output.

I include in my post the circuit of the wm8741 dac.

Thank

Bye

Gaetan

 

[gaetan8888]

Hello

No reply, circuits or suggestions ?

Thank

Bye

Gaetan

 

[delecoy]

BA3 FE

 

[Luke]

borbely jfet buffer?

 

[cochleus]

Here's one for example.

 

[gaetan8888]

Hello

I would connect the balanced Zen line stage output to an unbalanced input amp, do I use the Zen line stage +out as the live and the -out as the ground for my rca plug amp unbalanced input ?

And, can I use IRF640 in that Zen line stage, if so which modifications are need to use IRF640 ?

Thank

Bye

Gaetan

 

[2 picoDumbs]

If it is voltage output, a push pull jfet buffer will do the job.
See the example in the Sony Vfet article part 1.

 

[gaetan8888]

Hello

How about this circuit ?

Thank

Bye

Gaetan

 

[Luke]

Hi Gaeten, what is this circuit? It looks like a bipolar input Dynalo.

 

[gaetan8888]

Hello

It's from Bryston.

Bye

Gaetan

 

[2 picoDumbs]

Hello

How about this circuit ?

Thank

Bye

Gaetan

Yes that is a very good circuit.
You could do the same circuit with jfets and mosfets if you wanted.

However a low distortion buffer circuit makes more sense if you don't need voltage gain.

 

[gaetan8888]

Hello

That circuit need few more things to be usable, but I've simulated a variation of a Kaneda line preamp, I included it here.

Thank

Bye

Gaetan

 

[Luke]

Hello

It's from Bryston.

Bye

Gaetan

Thanks Gaetan, go the Bryston with jfets in front end

 

[gaetan8888]

Hello

I've done a fet circuit.

The LTspice simulation look good. But maby you can suggest me some improvements ?

I include the circuit and the distortions Spectrum.

Thank

Bye

Gaetan

 

[Nelson Pass]

Having gone through the 66 pages for that part, and relying on Fig 83,
I think you would be well served by the classic buffer like the one I use in
the revised B1. It measures below .001% in the regions of interest, the
potentiometer can be used to neutralize or enhance 2nd harmonic and the
input resistor can be played with to minimize unwanted response to high
frequency digital noise.

 

[gaetan8888]

Having gone through the 66 pages for that part, and relying on Fig 83,
I think you would be well served by the classic buffer like the one I use in
the revised B1. It measures below .001% in the regions of interest, the
potentiometer can be used to neutralize or enhance 2nd harmonic and the
input resistor can be played with to minimize unwanted response to high
frequency digital noise.

Hello

I did see your fet buffer, but I would need one with a balanced input and unbalanced output.

Thank and Merry Christmas

Gaetan

 

[nicoch58]

use linear or Minimum phase apodising filter ...this dac have 5 digital filter

 

[gaetan8888]

use linear or Minimum phase apodising filter ...this dac have 5 digital filter

Hello

I will use the wm8741 in hardware mode, so it's 3 digital filter only, as you can see in the image.

Bye

Gaétan

 

[nicoch58]

http://www.diyaudio.com/forums/digi...al-differential-mode-2-wire-control-mode.html