[sdiy] Preamp for a crystal transducer?

[Scott Gravenhorst]

Glen <mclilith at charter.net> wrote:
>I have an old Hammond reverb tank which uses a crystal transducer as the
>pickup element. I want to build my own preamp to use with this reverb tank.
>I have schematics for the original Hammond tube circuitry, but I'm not sure
>I could easily get all the parts I would need to build something similar. I
>want to build something without tubes. Does anyone have any suggestions for
>the type of circuitry I should use for the preamp? 
>
>I'm expecting that I'll need a very high input impedance, and if I build a
>quick and dirty opamp circuit, it might hiss like crazy. Would a discrete
>FET input buffer stage be better? 

IMHO, yes.  I also needed a high input impedance preamp for a Barcus-Barry
contact mic for acoustic guitar, I used a single stage FET preamp, 9 volt
battery operated.

It works wonderfully well, very simple, nice and quiet.  I used a 2N3819
FET, there may be better FETs, but it worked and I had them lying around.




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