[sdiy] PAiA Drum Tone Board - Tuning

[Jaroslaw Ziembicki]

20 years ago I built such TT-drums and I used an ordinary NPN transistor
(in parallel to the "ground" resistor) to bend the pitch - to get the famous
Simmons drum sound which was very popular those days.
The transistor was controlled from a simple "release-only" envelope through
a trimmer pot. The TT-oscillator itself was also built with an NPN
transistor.

Regards
Jarek



----- Original Message -----
From: "Scott Gravenhorst" <music.maker at gte.net>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Saturday, May 08, 2004 7:42 AM
Subject: RE: [sdiy] PAiA Drum Tone Board - Tuning


> From what I read on the PAiA site, the twin-T circuit can be tuned to a
point
> by varying the value of the resistor that connects from the two series
> capacitors to ground.  Looks like a job for a MOSFET transistor pair in a
> 4007UB or a 4069UB.  Or it could be done the way the PAiA site describes
using
> two series diodes in parallel with this resistor.  I would think that a
4069UB
> could tune 6 twin-T sections.  Control voltages would be applied to the
gates
> of the MOSFETs.