Manley Stereo Variable Mu® Limiter Compressor – High-End Tube Dynamics Processor
The Manley Stereo Variable Mu® is a world-renowned all-tube stereo limiter/compressor, favored by top mastering engineers and mix professionals for its musical compression, rich harmonic content, and unmatched tonal smoothness. Built with Manley’s classic hand-wired tube circuitry, the Variable Mu offers transparent dynamic control at low ratios</strong and> lush analog coloration when pushed — making it a go-to for everything from gentle bus compression to full-on analog glue.
A true modern classic, the Stereo Variable Mu® uses a real variable gain tube (the 5670 dual triode) to achieve compression — hence the name “Variable Mu.” Its dual-channel design with stereo link functionality makes it ideal for stereo buses, mix buses, or mastering chains. With switchable limit/compress modes, independent threshold and gain controls, and carefully selected components, this unit delivers the kind of analog warmth and dynamic control that digital plugins simply can’t replicate.
Key Features
- All-tube stereo limiter/compressor with hand-wired point-to-point construction
- True variable mu design using 5670 vacuum tubes
- Switchable Compress (soft-knee, 1.5:1–3:1) and Limit (harder knee, 4:1–20:1) modes
- Independent Threshold and Gain controls per channel
- Switchable stereo link for master bus and mastering applications
- Bypass switch per channel for direct signal comparison
- Balanced XLR and 1/4” TRS inputs and outputs
- Premium components: custom Manley transformers, ALPS potentiometers, and high-quality tubes
Technical Specifications
- Channels: 2 (Stereo or Dual Mono)
- Compression Ratios: Variable; approx. 1.5:1 to 20:1 depending on mode and threshold
- Attack Time: 25 ms – 70 ms (program-dependent)
- Release Time: 0.2 sec – 1.5 sec (program-dependent)
- THD: <0.3% @ +20 dBu output
- Noise Floor: -85 dB typical
- Inputs/Outputs: Balanced XLR and 1/4” TRS
- Tubes: 2x 5670 (gain), 2x 5751 (sidechain), 2x 7044 or 12BH7 (output)
- Power: 90–250 VAC, 50/60 Hz (universal input)
- Dimensions: 2U rackmount (19″ x 3.5″ x 10″)
- Weight: Approx. 16 lbs (7.3 kg)
Ideal For
- Mix bus compression with analog warmth and glue
- Mastering applications requiring tonal shaping and stereo cohesion
- Vocal, drum, and instrument tracking with natural tube compression
The Manley Stereo Variable Mu® is the definitive tube compressor for serious professionals — delivering iconic tone, powerful control, and timeless character in studios where sonic quality is non-negotiable.