Wiardgroup

hey grant,

thanks for the extremely informative answer! i've saved it in a text
file with all the other boogie info i could find from this list. 

how about the jumper switches? do they both need to be moved up in
order to maintain the same polarity between all the filter modes? and
the current draw of all the 1200 series modules?

will give it a whirl as a low pass gate later!

thanks again for the info,

gregg.

--- In wiardgroup@yahoogroups.com, "grantrichter2001" <grichter@a...>
wrote:
> It's a mode unique to photo-electric filters. Any other
transconductor (transistor, diode, 
> OTA) can not run to zero control current without making bad things
happen to the DC bias 
> and producing 15 volt thumps.
> 
> But photo-electric filters go completely off (0 Hz). This allows you
to use the filter as a 
> combined VCF and VCA.
> 
> In the West Coast model, the complex timbres are generated before
the filter via complex 
> oscillators, non-linear waveshapers, FM or additive synthesis. The
"gate" is then used for 
> final amplitude and spectral shaping.
> 
> The Boogie supports both modes, either straight subtractive with a
following VCA, like the 
> East Coast instruments, or gating and spectral shaping without a
following VCA, like the 
> West Coast instruments.
> 
> The main frequency control covers 20 octaves, 0 to 20 Hz, which is
10 octaves, and 20 Hz 
> to 20 kHz, which is another 10 octaves.
> 
> To "gate" with the Boogie, set initial frequency to zero and control
range to max. 
> Resonance is set to zero. A 10 volt signal into "Control In" will
then sweep the filter from 0 
> Hz to 20 kHz. The 6 dB output is approx. equivalent to the Buchla
292 "combo" mode, and 
> the 12 dB output is approx. equivalent to the 292 "filter" mode. But
the Hamamatsu opto-
> couplers decay in 20 ms., rather than the 200 ms. decay of the
VTL5C3/2 used in the 
> Buchla 292C.