Stereo tube limiter/compressor with M/S and T-Bar modifications

The Manley Stereo Variable Mu is an all-tube, transformer-coupled limiter/compressor: gain reduction is achieved by re-biasing variable-gain tubes (remote cut-off principle). This version is factory-fitted with the M/S and T-Bar modifications.

• Two operating modes: Compress (1.5:1, soft knee) and Limit (4:1, rising to 20:1 above 12 dB of gain reduction)
• M/S modification: separate M/S switches for input and output; with both engaged, the mid and side signals are processed separately (channel 1 mid, channel 2 side)
• With the channels working separately, stereo width can be adjusted via the gain reduction; M/S microphone recordings can also simply be decoded
• T-Bar modification: 4 x 6BA6 variable-gain tubes (matched pairs) instead of 2 x 5670; according to Manley it sounds less "squashed" than the 5670 with heavy limiting and allows more limiting with fewer artifacts
• Manley input and output transformers with nickel laminations in mu-metal cases, balanced inputs and outputs (600 ohms)
• Recovery in five steps (0.2 / 0.4 / 0.6 / 4 / 8 s), attack continuously variable from 25 to 70 ms, threshold continuously variable, stepped input attenuator
• High-pass side-chain filter (HP SC), link switch for linked or independent channels, hard-wire bypass, illuminated Sifam meters for gain reduction
• Frequency response 20 Hz – 25 kHz, max. output level +30 dBu, noise floor -85 dB
• Tubes per channel: 2 x 6BA6, 5751 or 12AX7, 12BH7 and 12AL5 as side-chain rectifier
• 19-inch rack unit, 2U: 19 x 3.5 x 10 inches (approx. 483 x 89 x 254 mm), the power transformer protrudes 3.5 inches at the rear; power consumption 80 W
• Hand-assembled in California, USA