Tube Amps / Music Electronics
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|previous: Arnaud Hello !
|8/10/1999 12:34 PM|
|R.G.||Re: Crybaby GCB-95 buffer ?|
My amp-tech friend called me one day about one of these.
1) he found the 2M2 resistor there as well. The 22pf is there to shunt RFI to ground, otherwise the thing picks up your local radio stations.
2) I don't know why the treble losses are so high. The one my friend asked me about had no noticeable treble loss, just a huge amount of hiss. I think that the darlington had been damaged somehow.
You do know that the JFET buffer fits right in the PCB where the darlington buffer is now, don't you? Remove the 1M8 pullup resistor and put a low noise JFET in there. - that's all there is to it. That's what we did to the noisy one, and it got lots quieter.
It is possible that your darlington has been damaged as well. You could try replacing the darlington with another MPSA13 to see. You could also stuff in the JFET buffer.
|Arnaud Well, thank you, Joe & R.G.|