Manley Vari-Mu

Manley Vari-Mu

Stereo Tube Mastering Compressor Daily Rate: $75

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The MANLEY VARIABLE MU® LIMITER COMPRESSOR 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 the 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 precious vintage Fairchild 670 also uses this technique and is one of few all-tube compressor to do so, that we know of. 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.


The COMPRESS mode is soft-knee 1.5 to 1 ratio while the sharper knee LIMIT mode starts at 4 to 1 and moves to a more dramatic ratio of 20 to 1 when limiting over 12dB. Interestingly, the knee actually softens as more limiting is used. Distortion can be creatively used by turning up the Input and turning down the Output while using very little or no compression.




MANLEY input & output transformers with nickel laminations in mu-metal cases with flat frequency response from 20Hz-25KHz 


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 dual INPUT attenuator 

RECOVERY 5 steps: 0.2s, 0.4s, 0.6s, 4sec., 8sec. 

Variable ATTACK: 25msec-70msec 

Continuously variable THRESHOLD 

LIMIT (4:1 to 20:1) or COMPRESS (1.5 to 1) 



Several units can be linked for Surround (custom order ) 




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 Voltage Frequency: 50~ 60Hz 

Dimensions: 19" x 3 1/2" x 10" (occupies 2u) 

Shipping Weight: 23 lbs. 




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