This is a repost of my SSL Build Thread. Thanks to Gyraf.dk for the schematic plans.
The compressor is a clone based from the SSL4044E desk (1985 era). The SSL mixbus is actually an integrated part of the desk's main quad fader and autofade system. Schematics and mods can be found below the article.
I also did some mods on my unit. Mainly, adding transformers at the output. Originally, the unit uses opamps for balanced outs. I have some MCI 416 output trafos that I used for my SSL unit.
Screenshot of my PCB stuffed with components. A few missing parts but almost there.
Building the rack case. Drill holes, and file a rectangular hole for the VU meter (ammeter).
Assembling the rack case and making sure all the parts I need to start the Final Build are complete.
There is a daughterboard that contains the selector switches for the RATIO, ATTACK, RELEASE selectors.
Wiring the balanced outputs. (The transformers are not yet included in this photo.)
You can also see the Toroidal transformer for the power supply unit.
It sounds so good, I built a 2nd unit.
I used a digital caliper to make sure the locations of knobs, switches, vu meters are identical on the 2nd unit.
Of course, we need some obligatory sound clips. I used the raw outputs from an Emu XL-7 synth to the SSL compressor, then to the audio inputs of my 828mk2.
The first thing you'll hear is the uncompressed signal for approx 15 seconds, followed by the compressed signal. At around 28seconds, I switch it back to uncompressed. Click on the waveform to listen.http://www.fivefish.net/diy/ssl4000compressor/audio/sslcompressorsample.mp3
Click here for schematics
. There's been some mods
to the original schematics for use with THAT VCAs. This page contains adjustments to the resistor values.