The GSSL is a clone of the stereo buss compressor found in SSL4000-series desks.  Because of it’s affordability and relatively low difficulty, the GSSL has become a very popular project with many PCBs and mods available.

Images courtesy of Gyraf Audio and FiveFish Studios

Notable Features:

• Designed for DBX202x or THAT2180/2181 VCAs
• Uses all modern easily sourceable components
• Ratio, attack, and release pots

Possible Modifications:

• Turbo Mod
  • Changes the sidechain from summed (mono) to stereo.  This makes the GSSL behave more like the original SSL.
• CRC Filter Mod
  • Fixes power hum problems inherent in the original GSSL design.
• VU Meter Mod
  • Usually GSSL builders use a peak meter.  The VU meter makes the “feel” of the compressor closer to, say, the 1176.
• Super Sidechain
  • Adds adjustable 60, 90, 130 & 200hz high-pass filters, Tilt-Medium and Tilt-Loud sidechain eq curves, and the option for an external sidechain input.
• Crush’n’Blend
  • Adds wet/dry mix control

Price:

• 25€ for PCB from PCB Grinder
• 25€ for GSSL + super sidechain PCBs from PCB Grinder

Modifications:

• $9.95 for Turbo PCB from Expat Audio
• $30 for Turbo kit from DIY Parts Supply
• 12€ for Super Sidechain PCB from Gustav
• $9.95 for VU Meter PCB from Expat Audio
• $6.95 for CRC PCB from Expat Audio
• $16 for CRC kit from DIY Parts Supply

More information:

• www.gyraf.dk.
• A blog about building a GSSL.
• Five Fish’s GSSL build blog with sound clips.