[sdiy] Vactrols & Lopass Gates

[mark verbos]

a C&K 7211 doesn't have a third contact, the middle position leaves one 
throw of each pole connected. In the 292B the middle position leaves the 
resistor and the cap connected, or "both". In the 292c the input 
resistor makes the gain greater, so the gain is lower for 2 of the 3 
positions, just like the 292c. Without this, the lopass gate will work, 
it will just be louder in the middle position than in the other 2.

Mark

Peter Grenader wrote:

> Mark -
> 
> Have a look at the Buchla's schematic B2420B.  It's the one from the CBS
> system.  Note the switch symbol - two contacts -- dual switch.  The top one
> shorts out the filter, the bottom one kills the feedback.  There is no
> connection shown for a third center position.  The off (center) keeps the
> filter going but kills the feedback thru the FET.  There is a marketable
> sonic difference between the center and down (LP) positions.
> 
> Try it with a standard double pole triple throw.
> 
> 
> mark verbos wrote:
> 
> 
>>The Buchla 292B uses a C&K 7211 On-ON-ON switch. I am sorry, but it's a
>>fact. I have built them all as well. 
> 
> 
>