Manley Stereo Variable Mu Limiter Compressor “The Works”

Manley Stereo Variable Mu Limiter Compressor "The Works" is the standard version of the compressor carrying both factory modifications at once: T-Bar in the gain control stage and MS in the signal path.

Deeper reduction and separate work on the centre

The two modifications answer different limitations, but together they open a working range the base version never reaches. T-Bar swaps two 5670 triodes for four 6BA6 pentodes, which keeps the limiting curve smooth even when you go past six decibels of reduction. MS splits the signal into sum and difference before the gain stage, so you can press on the centre of the mix alone and leave the sides untouched. The result is dense, heavily processed material that loses neither width nor air despite the amount of reduction.

The valve itself as the gain control

A variable mu circuit has neither a VCA nor an optical cell. Gain changes through the bias voltage of remote cutoff valves, so the reduction is not applied to the signal, it is how the amplifying stage behaves. That produces the characteristic response: the harder you push it, the gentler the curve looks, instead of a hard knee at the threshold. The mode switch gives 1.5:1 in Compress and 4:1 to 20:1 in Limit, attack is continuously variable from 25 to 70 ms, and recovery has five settings: 0.2 s, 0.4 s, 0.6 s, 4 s and 8 s. A high pass filter in the sidechain at -3 dB @ 100 Hz keeps the low end out of the detector so the kick does not drive the whole mix.

KEY FEATURES

• T-Bar modification: four 6BA6 pentodes in the gain stage
• MS modification with mid-side encoding and decoding
• Both factory modifications in a single unit
• Two channel compressor and limiter with an all-valve path
• Compress mode at 1.5:1 and Limit mode from 4:1 to 20:1
• Attack continuously variable from 25 to 70 ms
• Recovery in five steps: 0.2 s, 0.4 s, 0.6 s, 4 s and 8 s
• High pass filter in the sidechain at -3 dB @ 100 Hz
• Manley IRON transformers with nickel laminations
• Channel linking for stereo operation
• Hardwire bypass for comparison against the unprocessed signal
• Illuminated Sifam gain reduction meters

TECHNICAL SPECIFICATIONS

• Variable gain valves: 6BA6 x4 in the T-Bar modification
• Amplifying valves: 5751 or 12AX7 x2
• Output valves: 12BH7 x2
• Sidechain rectifier: 12AL5 x2
• Frequency response: 20 Hz to 25 kHz (±0.1 dB)
• Maximum gain: 35 dB
• Maximum output: +30 dBu with 26 dB of headroom
• THD: below 0.1% at 1 kHz
• Noise floor: -85 dB typical
• Balanced inputs and outputs, 600 Ohm
• Controls: conductive plastic potentiometers, continuously variable
• Dimensions: 19 x 3.5 x 10 inches, 2U; power consumption 80 W