[sdiy] Buchla Lowpass Gate Switch

[Fernando de Izuzquiza]

Hi,

In the Silonex site there is many info/examples about vactrol based 
VCAs and many variations and methods to get better "muting", ways of 
controlling the LED, etc.

I think I will try different vactrols when I build mines (LPGs). Two 
5C3, a 5C3/2 and two Silonex also. The NSL-32SR3S it's fast and 
selected for a tighter resistance value. I'd like to see how it works 
on it...
I assume a faster vactrol will sound less Buchla.

I found a 3P3T on-off-on switch at RS-components, 103-5552. Is this the 
right one for PeterG's approach?

Fernando



 > De: Peter Grenader <peter at buzzclick-music.com>
 > Fecha: Wed, 11 Aug 2004 21:22:24 -0700
 > Para: mark verbos <mverbos at earthlink.net>, synth diy
 > <synth-diy at dropmix.xs4all.nl>
 > Asunto: Re: [sdiy] Buchla Lowpass Gate Switch
 >
 > I might add that I didn't use single vac's on the rev Bs I've made, 
but
 > opted for the same single 3/2 dual element used in the rev c.  I did 
this
 > for cost reason's only.  As far as the performance, the sonic 
characteristic
 > of the two, the only differences I can hear is slightly less gain in
 > amplitude operation and a bit more resonance in lowpass mode, which I 
assume
 > comes from the  properties of the FET.
 >
 > In any event, the rev B's FET allowed for the additional bleed-killing
 > inverted feedback I added, I haven't been able to do this with the 
rev c.
 >
 > - P
 >
 >
 >
 > Peter Grenader wrote:
 >
 >> Mark-
 >>
 >> I used a straight double on-off-on on my rev B's and I've got combo 
in the
 >> center. I'll be happy to post an mp3 to illustrate this!
 >>
 >> Have a look as the schematic- the top half of the switch puts 15K 
across the
 >> output of the second vactrol element, killing the filter.  The Rev C 
does
 >> the same thing, but does so with only 10k. The bottom half of the 
rev B
 >> switch increases the cap value, (.0047), just as C does. The 
additional
 >> third switch element in the rev C adds 15k to the input signal's 
amplifier,
 >> increasing it's gain.  Granted, the rev B doesn't do this, but this 
addition
 >> does not effect the mode switching, it just ups to output of 
amplify-only
 >> operation. This is why I didn't see that an on-on-on was required 
and as it
 >> turns out, it seems to work fine without one.
 >>
 >> - P
 >>
 >>
 >>
 >>> it actually doesn't save anything because the switch the rev B used 
is a
 >>> On-On-On switch, which is even more rare and pricey than the 3PDT 
one!
 >>> The reason i modded the rev C was because of price. I wanted a 
cheap and
 >>> simple solution. Also the wiring is easier than using multiple pole
 >>> switches. Fewer wires, smaller switches that can be closer together,
 >>> easier to get, cost less. Seems like an obvious choice to me, but I
 >>> guess not for everyone...
 >>>
 >>> mark
 >>
 >
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