The SB4000 is a stereo buss compressor based on Gyraf’s GSSL. The SB4000 incorporates many of the mods that have been developed for the Gyraf’s clone, making it a “next generation” GSSL.

Notable Features:

• Fits in a 8″ deep 1RU case (smallest size commonly available)
• PCB set includes main board, power supply, and control board
• Incorporated mods:
  • Turbo: provides the option for mono (summed) or stereo sidechain
  • Super sidechain x2: adds sidechain high-pass filters and “tilt” eq curves
  • VU bargraph
  • Relay bypass
  • Power supply redesigned from the (sometimes) problematic GSSL
• Supports DBX202x and THAT218x VCAs

Price:

• $100 for PCB set and silk screened front panel

More Info:

• Serpent Audio’s products are available at SerpentAudio.com.
• The support thread
• Schematic
• An excellent blog post from Evolutionary Theory detailing his build process.