MANLEY VARIABLE MU

Variable Mu is the name describing using the "remote cut-off" or re-biasing of a vacuum tube for compression.

The precious vintage Fairchild 670 also uses this technique and is one of few all-tube compressor to do so.

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. You might notice that the Vari Mu has a ganged input control, but do not jump to conclusions that it is mono-unfriendly.

There are separate threshold and output controls to make compensations with plus you can always adjust your individual source levels elsewhere.

The advantage of the stereo input control becomes dramatically clear when you switch to LINK mode, and that’s what the Variable Mu does better than anything else: final mix, 2-track, or mastering limiting and compression.


Features & Specifications :


* MANLEY input & output transformers with nickel laminations in mu-metal cases with flat frequency response from 20Hz-25KHz
* BALANCED INPUTS & OUTPUTS (600ohms)
* 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)
* Large ILLUMINATED Sifam METERS
* STEREO LINK SWITCH
* 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
* Dimensions: 19” x 3 1/2” x 10” (occupies 2u)
* Shipping Weight: 23 lbs.