Tube questions

[Doug Tymofichuk]

Hello again, all!

Here are a few silly tube questions for those interested:

I am just beginning to build a dual VCA module for my tube 
percussion synth. The more that I think about it, the more 
that I feel that I would like to be able to patch signals 
between any section of any module. So I have decided to 
keep all signals in the range of less than +/-15 volts. So 
any outputs from tube based modules will have to be 
attenuated down to this range (the easy part!). Also, any 
inputs to tube based modules will have to be in this range 
as well (the not so easy part!). Anyone have suggestions as 
to a good, simple tube gain stage for this application? 
Seems to me that a gain of about 10 should work fine in 
most cases.

How does one determine whether a tube circuit should have a 
standby switch/timer, is it just for high power output 
tubes or tubes run above a certain voltage or what? Should 
I worry about it at all for my tube synth, or does it just 
apply to power amplifiers?

Is it possible to use a power rectifier tube as a detector 
or other signal processor? Any other interesting uses for 
them? (I have a bunch here sitting around begging to be 
used.)

>From Eric Barbour:
>1) John Atwood has a General Radio "Broadband Noise Source"
>from the 1950s. It contains a 6D4 thyratron, biased to be 
>conducting all the time, and with a large donut-shape 
>alnico magnet surrounding the tube.
>(anyone care to guess why?....)

Eric, did you ever enlighten us on this one? (maybe I 
missed it) Was I even close? Do you by any chance have a 
schematic?

I am now trying to decide whether to build a solid state 
ADSR for controlling the VCAs, or maybe I will spend a 
bunch of time trying to design a tube envelope generator 
with just attack and decay for now. Either way, I can 
always upgrade later.

All for now, 
----------------------
Doug Tymofichuk
dougt at cancerboard.ab.ca