Which way is this FET before i build..Fet Preamp Cable Build?

Started by finkfloyd, March 17, 2006, 12:15:21 PM

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finkfloyd

Heres Don Tillman's descrete preamp cable..
But the transistor orientation isnt clear, Logic tels me that its "dsg" , but could quite easily be "gsd"

Am I correct? thus making this post pointless?   :-\

Also Im gonna have to substitute 20K, for 22k, and 3.0M for 3M3..


vanhansen

The drain connects to the phantom power, gate us where signal is coming in off the 20k resistor and source goes to ground via the 2.2k resistor.  You should be OK with your substitutions as well.  They're within the +/- 10% range for carbon film resistors.
Erik

finkfloyd

Hi, thanks, Just built it, was a tight fit!! and it works just fine, ..

Plugged into the phantom power box, but i cant really tell much difference so far over my standard cables..

finkfloyd

I just re-read your post,

Quotegate us where signal is coming in off the 20k resistor and source goes to ground via the 2.2k resistor

that would surely make the FET orientation from top to bottom "DGS"?

I mean the cable works as is, But I cant tell the difference over a standard cable, and something tells me i should be able to.

Eric H

Quote from: finkfloyd on March 18, 2006, 11:42:35 AM

I mean the cable works as is, But I cant tell the difference over a standard cable, and something tells me i should be able to.

Describe the equipment you are using it with.

At  least it is transparent  :icon_wink:

-Eric
" I've had it with cheap cables..."
--DougH

finkfloyd

Hi, the cable is plugged in via xlr socket to the phantom power box, then direct into my PC's audigy 2 ZS input box, without the preamp[in the audigy] turned on...

I dont own a real amp just yet.

I use amp emulation software for now.

toneman

where's the Drain resistor??
Where's the (output)coupling cap??
Phantom pwr is approx 38VDC, correct??
U might have to alter the Drain R for the higher V  (?)
Looks like U don't have all the parts on your schemo(?)
Till's PA is supposed to have a *bit* of gain.
In your circuit, doesn't seem that the J201 is actually working.
Re-look at Tillman's schemo....
google for "J201 datasheet" for the package/pinout configuration.
afn
T

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