Sunday, 1 December 2013

The Soundlab Diaries - Part 2 - First stage build.

Front panel, half way through construction.
The final design was based arund a Music From Outer Space SoundLab PCB. This is designed to be a very simple switched synthesizer for making sound effects,  but it always screamed out to me as being capable of much more.
It is built on 72h (14.4") 3U (Eurorack) format panel, and the lettering was printed on a laser printer, laminated, and glued to the metal before trimming. It is the first time I have tried this method, and it produces a neat easily useable result, but nobody is going to be fooled that it is a professional job.
The sellotape to protect the corners and the Stig sticker are not staying :-)

Modifications from original

Behind the front panel, with main PCB and extension board
Like I said this little beast is capable of more than its original design and I could not resist building in the following modifications.
  • Routing switches changed for 4mm sockets,
  • LFO - Rate in fast mode reduced to 30-0.05 Hz, by increasing C14 to 22nf
  • LFO - LED on triangle output
  • LFO - Inverted triangle output added
  • AR - Threshold level on external input
  • AR - LED
  • AR - Inverted AR output added
  • AR - Attack/On phase output added to provide additional control gate.
  • VCO - VCO1 upgraded to be exactly the same as VCO2
  • VCO - Trigger input via a capacitor so they trigger on any square wave
  • VCO - Triangle output added (Not tested yet)
  • VCF - Control front end modified for logarithmic response (Not tested yet)
  • VCA - Control front end modified for logarithmic response (Not tested yet)
  • Control inputs on VCOs, audio and control on VCF and VCA have one direct socket (input 1) with no attenuator and at least one socket with an attenuator
  • All outputs via 1K resistor to eliminate problems with shorts, and multiple outputs can be directly connected together.
The circuitry for these additions and modifications are on a couple of fiber glass matrix boards, one at each end or the main panel, which are held in place by PCB brackets mounted behind potentiometers


Today, 1st December 2013,  the LFO, AR are completely working, the VCOs are working but not of the modifications have been implemented yet. The VCF and VCA have not been started.
Well that was what I thought...

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