MOTM

I'm very curious about the pentode VCA.  It looks like a very promising
module for a number of reasons.

http://www.cgs.synth.net/modules/cgs27_tube.html

The parts are inexpensive and the design seems relatively simple.  In
fact, I'm thinking it would take less time and money to build than an
OTA-based design.  Perhaps more importantly, it only uses +15V for
the plate voltage, so it does not require a separate power supply and
it is relatively safe for DIY.

The use of +15 plate voltages with pentodes also opens up the
possibility of other voltage-controlled modules using tubes such as
filters and waveshapers.

How well does it work??  Do you have any examples how it sounds?
While cut-off tubes are used in compressors, I was under the
impression they didn't work well as gates. Did you have to bias the
control voltage??  Did you connect the suppression grid to the
cathode??

Did you use a PCB from CGS??  There appears to be two, a CSG65 and a
CSG27.   What did you use to supply the heater voltage??  I'm
thinking a dual module using 6064 tubes would draw around 600mA,
which would be about 75% of an MOTM-900. Then there is the other CGS
tube VCA, that uses a tube that only draws 13mA:

http://www.cgs.synth.net/modules/cgs65_vca.html

Unfortunately, I am totally unfamiliar with the 1J24B /1J24B  and I
cannot seem to find anything about it online written in English.

I'm not familiar with directly-heated cathodes, so I'm a bit confused
what pin 3 does, and the heater circuit shown in the CGS65 schematic.
It also looks like the suppression grid is connected to the negative
rail??

Thanks for the update.  Your consideration is appreciated.

On 3/4/07, Richard Brewster put forth:
>I got around to updating my website today.  I added the long promised
>Wogglebug project page with full schematics and pictures, plus the three
>latest modules:  Blacet StonZ Phaser, Oakley Superladder VCF, and CGS
>Tube VCA / Timbre Modulator.  And a picture of the back of my CGS
>Digital module, which has 8 circuit boards.  I took a new photo of the
>MOTM-650, too.
>
>No, I'm not done, yet!  I am waiting for more MOTM to be announced.
>
>http://www.pugix.com
>
>Be sure to refresh your browser cache.
>
>-Richard Brewster