MANLEY STEREO VARIABLE MU®
The Legendary All-Tube Compressor
The Manley Variable Mu Limiter Compressor stands as a legendary piece of audio equipment, earning its place as a standard in mastering studios and contributing to numerous hit records. This all-tube, all-transformer compressor is designed to act as the glue that holds a mix together, providing the final polish and professionalism to audio productions. The term "Mu" in tube-speak refers to gain, and the Variable Mu is a registered trademark for this specific limiter compressor.
Key Features
- Tube-Based Compression:
- The Variable Mu operates by utilizing the "remote cut-off" or re-biasing of a vacuum tube to achieve compression. This technique, also used in the vintage Fairchild 670, involves the constant re-biasing of a dual triode (5670) by vacuum tube rectified side-chain control voltages, resulting in smooth gain changes.
- Two Operating Modes:
- The COMPRESS mode features a soft-knee 1.5 to 1 ratio, offering gentle compression. On the other hand, the LIMIT mode starts at 4 to 1 and increases to a more dramatic ratio of 20 to 1 when limiting over 12dB. The knee softens as more limiting is applied.
- Distortion Control:
- The Variable Mu allows creative use of distortion by adjusting the Input and Output controls while using minimal or no compression. This feature provides flexibility in shaping the character of the processed audio.
- Ganged Input Control:
- While the Variable Mu has a ganged input control, it is not mono-unfriendly. The unit is suitable for stereo operation, and separate threshold and output controls allow compensations. The ganged input control becomes particularly advantageous in LINK mode.
- LINK Mode:
- In LINK mode, the stereo input control shines, making the Variable Mu ideal for final mix, 2-track, or mastering limiting and compression. It imparts a unique quality described as "pouring a bowl of sweet cream over the mix," adding a desirable warmth and cohesiveness.
The Variable Mu Limiter Compressor's ability to impart a smooth and musical character to audio, combined with its versatile controls, has made it a sought-after choice for mastering engineers and audio professionals. As a quintessential all-tube compressor, it continues to be a staple in the audio industry.
