The Aphex Model 661 is a totally new type of compressor

              incorporating vacuum tube technology with the latest

              innovations in audio compression. This single-channel

              compressor/limiter is loaded with features, consolidating

              for the first time in one rack space, three patented Aphex

              circuits: Tubessence®, Easyrider®, and High Frequency

              Expander®.

• Auto or full Manual operation. In Auto mode, compression parameters constantly change for best sound
• A true tube circuit (Tubessence) in the output stage for a "warm", "live" and "full" sound
• HFX allows the use of high compression ratios without the loss of high frequencies
• SPR increases the apparent bass energy level, without amplitude equalization or bass boost
• Use Sidechain Access sends jacks for creative processing (de-essing and ducking)
• Stereo, dual mono or master/ slave operation for total flexibility