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Manley VARIABLE MU? Stereo Compressor Limiter Mastering Version Detented + MS Option & T-Bar

by Manley
£6,208.80 inc. vat
£5,174.00 ex. vat
Please contact us for availability.

Manley VARIABLE MU + MS Option & T-Bar

The Manley Variable Mu Limiter Compressor with T-bar mod is one of the very few compressors that has become a real standard in Mastering studios and contributed to most hit records over the last decade and probably the next. "Mu" is tube-speak for gain, and Variable Mu is Manley's registered trademark for this limiter compressor. It works by using the "remote cut-off" or re-biasing of a vacuum tube to achieve compression. 

The MS modification opens the door to stereo encoding and decoding as well as exciting image enhancement processing capabilities. For instance, setting to compress only the in-phase information allows the augmentation of the stereo image as the out-of-phase content is left untouched. Or, conversely, if you need a "more-mono" mix for broadcast, or vinyl-cutting for instance, you can set it to kill off more of the out-of-phase info which leaves more in-phase material in the final result.

The T-Bar Mod provides a replacement for the obsolete 6386 tubes in earlier Manley Variable Mu® units or convert later 5670 units to have the same limiting characteristics of the original 6386 for smoother operation. To install a converter board and surrounding modifications to enable usage of two 12BA6 or 6BA6 single pentodes wired in triode mode to take over the duties of a single envelope dual triode 6386 or 5670 (per channel).

The precious vintage Fairchild 670 also uses this technique and is one of few all-tube compressors in the professional market. Even the side-chain has glowing rectifier bottles. How’s it work? The unique 5670 dual triode is at the center of the peak-reducing and compression action constantly being re-biased by the vacuum tube rectified side-chain control voltages which cause this tube to smoothly change its gain. Just like that.


  • Maximum gain: 35dB
  • Max. output:
    • +30dBu (26Vrms) 26dB Headroom
    • <0.1% THD @ 1KHz Noise floor: -85dB typical
  • Power Consumption (120/240VAC): 80 watts
  • Unit is factory set for 100V, 120V or 220-240VAC operation for original destination country's mains voltage.
  • Operating Mains Voltage changeable with power transformer changeover switch and fuse value change.
  • Mains Fuse Value for 100~120VAC operation: replace with 1.25A as of 10/2011
  • Mains Fuse Value for 220~240VAC operation: replace with 0.6A (600mA) as of 10/2011
  • Mains Fuse Type: MDA or MDL SLO-BLO Time delay 1 1/4" x 1/4"
  • Mains Voltage Frequency: 50~60Hz
  • Dimensions: 19” x 3 1/2” x 10” (chassis occupies 2u) Power transformer protrudes 3.5" out the back of the chassis.
  • Shipping Weight: 23 lbs.