Manley Stereo Variable Mu Mastering Version with MS Mod combines stepped Grayhill controls with mid-side processing built into the signal path of the unit.
Recall and MS processing in one unit
Working in MS during mastering has one awkward property: it is easy to overdo and only notice on a different system. Stepped controls solve that from the workflow side, because every decision is a position you can note and step back from, instead of hunting for the previous setting from scratch. The MS modification splits sum and difference before the gain stage, so you press on centre or sides separately, and repeatable settings let you compare both versions calmly. This is the combination for a record where every track has to hold the same character.
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
- Mastering version with stepped Grayhill switches
- MS modification with mid-side encoding and decoding
- Repeatable settings across a whole album
- 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: 5670 x2 in the standard version
- 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: stepped Grayhill switches with 1% metal film resistors
- Dimensions: 19 x 3.5 x 10 inches, 2U; power consumption 80 W
