ManleyVariable Mu Limiter Compressor - T-Bar Mod

Manley Variable Mu

Resembling the original 6386 tubes without the issues of noise and microphonics, Manley has developed the Variable Mu T-Bar modification for legendary compression and limiting in a new form. Used widely for mixing and mastering to add bus compression or limiting, the Variable Mu offers renowned sound throughout numerous genres for glueing your entire mix together. Packed with tubes, transformers, and other tech, the Variable Mu provides tons of headroom, gain, and beef to any signal needing some light love or heavy squashing.

Each step of the way, the Variable Mu takes tube gain staging (hence the Mu), amplification, and leveling with maximum high-voltage headroom for a clean and powerful signal. The input gain is ganged for both channels, but this should be seen more as a pro than a con considering it's general use for stereo mixes and two-tracks. Each channel can be set to a gentle compressor with a 1.5:1 ratio, or be pushed into maximum drive with a limiter that starts off at a 4:1 ratio but pushes up to 20:1 once the gain reduction surpasses 12dB.

Dynamic control is implemented with a continuous threshold control for fine-tuning gain reduction, while the time shaping tools feature a relatively smooth attack time of 25ms to 70ms and a quite slow release with times of 200ms all the way to 8 seconds. All three of the controls can be set individually or in a stereo link for one set of controls affecting both channels, and all compression and limiting can be easily viewed via the backlit gain reduction VU meters. The final output controls are unique for each channel making it very easy to dial in the perfect amount of leveling per channel.

The current Variable Mu relies on 5760 tubes similarly found in the Fairchild 670, but originally the Variable Mu used 6386 tubes that didn't squash as much. The issue with keeping the 6386 tubes lies in the lack of availability of the originals, and the degraded nature of what's left presents issues such as noise and microphonics. For those looking for that classic tube wiring without all these issues, the T-Bar mod recreates near-identical reduction and limiting curves by swapping the dual triode setup with a pair of 6BA6 pentodes wired as single triodes.

For a smoother but still powerful and large sound from your limiting and compression, opt for the Manley Variable Mu T-Bar mod.

Variable Mu Features

• Stereo tube limiter/compressor
• T-Bar mod replaces dual triode 5670 with a pair of 6BA6 pentodes wired as single triodes
• Balanced transformer inputs and outputs with flat frequency response
• All-tube signal path, including variable gain, amplifying, and output
• Each channel has a limit/compress switch and a hardware bypass switch
• Compression is soft knee at a 1.5:1 ratio, Limiter is a sharper knee starting at a 4:1 ratio and can achieve up to a 20:1 ratio
• Detented input gain ranging +/-8dB over an 11-position control
• Continuous control over threshold and attack (25 to 70ms)
• 5-position recovery control (200ms to 8 sec)
• HP SC input sets a 1-pole filter at 100Hz
• Sep/Link sets whether the threshold, attack, and recovery are individual to the channels or linked controls