The MANLEY VARIABLE MU LIMITER COMPRESSOR has been their best selling product for many years. It 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 their 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 they 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. Just like that. 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. See the gain reduction curves here!
You might notice that the Variable Mu Limiter Compressor has a ganged input control, but do not jump to conclusions that it is mono-unfriendly. Track away! There are separate threshold and output controls to make compensations with plus you can always adjust your individual source levels elsewhere, right? The advantage of the stereo input control becomes dramatically clear when you switch to LINK mode and that's what their Variable Mu Limiter Compressor does better than anything else: final mix, 2-track or mastering limiting and compression. Like one reviewer put it: "It's like pouring a bowl of sweet cream over the mix." Mmmmmm. Yummy. Give your music a big hug.
Features: - Manley Labs Compressor Features - Manley input & output transformers with nickel laminations in mu-metal cases with flat frequency response from 20Hz-25KHz - Balanced inputs and outputs (600 ohms) - Fully differential ALL-TUBE circuitry using one each 5670, 5751 (or 12AX7), 7044 (or 5687) & 12AL5 per channel - Independently regulated B + and Heater supplies - Hard-wire BYPASS switch - Stepped switch input attenuator as of 10/2011. (older units use Silent dual-ganged potentiometer) - 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) - HP SC: High Pass Side Chain Filter -3dB at 100Hz - Stereo link switch - Several units can be linked for surround (custom order) - Maximum gain: 35dB - Max.output: + 30dBu (26Vrms) 26dB headroom - Less than 0.1% THD at 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
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