Manley Variable Mu Mastering Version

Manley Variable Mu Mastering Version is the perfect addition to any professional mastering facility. In fact, since its introduction, it’s quickly become an industry standard mastering tool – and it’s the limiter/compressor responsible for an incredible amount of hit records over the last decade. The Manley Variable Mu Mastering Version’s detented switches let you easily dial up or log favorite settings. Likened to “pouring a bowl of sweet cream over a mix,” if you’re looking for the ultimate in mastering weaponry for your pro sound armory, you’ll find it in the Manley Variable Mu Mastering Version.

Behaves much like the vintage Fairchild 670
The Variable Mu uses a compression/limiting technique similar to the beloved vintage Fairchild 670. As “mu” means gain, the Variable Mu Mastering Version offers true variable gain by constantly re-biasing the unique 5670 dual triode at the center of the peak-reducing and compression action, allowing the tube to smoothly change its gain. The Variable Mu Mastering Version offers a soft-knee 1.5:1 compression ratio while its limit mode is sharper knee, starting at 4:1 and moving to 20:1 when limiting over 12dB. The knee softens the more limiting is used. To achieve more sounds, you can creatively use distortion by turning up the input and turning down the output while minimizing your use of compression.

Premium switches, for logging and recalling settings
Unlike the standard Variable Mu, which uses smooth-moving pots, the mastering-dedicated Variable Mu Mastering Version offers detented steps. This way, you can easily log your settings or recall them. The steps are built with 1% metal film resistors on sealed gold-contact Grayhill switches.

Manley Variable Mu Mastering Version Features:

  • Detented steps using 1% metal film resistors on sealed gold-contact Grayhill switches
  • Manley input & output transformers with pure nickel laminations in mu-metal case with flat frequency response
  • 20Hz-25KHz frequency response
  • Balanced Inputs & Outputs
  • Fully differential all-tube circuitry using one each 5670, 5751, 7044, & 12AL5 per channel
  • Independently regulated B+ and Heater supplies
  • Hard-wire Bypass switch
  • Silent conductive plastic input attenuator
  • Recovery 5 steps: 0.2s, 0.4s, 0.6s, 4sec., 8sec. (Not a 12-step recovery)
  • Variable Attack: 25msec-70msec
  • Continuously variable Threshold
  • Switch for Limit or Compress modes
  • Front-panel mounted Meter Adjust
  • Limit (4:1 to 20:1) or Compress (1.5:1)
  • Large Illuminated Sifam Meters
  • Stereo Link Switch
  • Maximum gain: 35 dB
  • <0.1% THD @ 1KHz Noise floor: -85dB typical
  • Max. output +30dBm (26Vrms) 26dB Headroom
  • Power consumption (120/240VAC): 80 watts
  • Dimensions: 19″ x 3 1/2″ x 10″ (occupies 2U)
  • Shipping weight: 23 lbs.


Number of Channels 2
Controls Recorvery, Output, Threshold, Attack
Threshold Spec Not Available
Ratio LIMIT: (4:1 to 20:1) or COMPRESS: (1.5 to 1)
Frequency Response 20Hz-25KHz
Side Chain Inserts No
Inputs 2 x XLR
Outputs 2 x XLR
Sidechain I/O No Sidechain I/O
Rackmount Spaces 2U
Height 3.5″
Depth 13.5″
Width 19″
Weight Shipping Weight: 23 lbs.