New issue 5 ADSR/VCA boards now available

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New issue 5 ADSR/VCA boards now available

Post by Synthbuilder » Wed May 16, 2018 5:47 am


The issue 5 boards are now available and all documentation is online.

The previous issue, and indeed the three issues before that, go back to a design I made in 2004. Then I needed to move away from the Omeg 16mm pots with which I was having reliability and sourcing issues. I couldn't get hold of good log pots from Spectrol or Bourns so I decided to do the log function required electronically. I used a THAT2181 as the control element for a one pole low pass filter, or slew generator, which was used to create the required waveforms. It's worked well over the years but I felt it was time for a small change particularly with the need for a perhaps a more speedier attack time. Not that 0.75 ms was particularly sluggish.

So with issue 5 we have the same feature set but with a much larger control range. I'm now using the VRG core circuitry as the slew generator. Attack times now can be varied continuously over 0.2 ms to 32 s, and decay and release times from 0.38 ms to 50 s. The slow setting increases these by a factor of eight or so.

The board is slightly smaller coming in at 81mm deep. It's a four layer design which keeps the internal noise levels down.


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