• Manley IRON® input transformers
• 4 x hand-matched 6BA6 vacuum tubes
• Transformer-Balanced XLR inputs
• Manley HIP function raises soft dynamics without squashing louder passages
• MANLEY POWER® High Voltage Switched Mode Power Supply custom designed for our vacuum tube audio circuits
• INPUT Level Preset 3-way switches -3dB, 0, +3dB
• Continuously variable OUTPUT level controls
• Unity Gain set INPUT to "0" and OUTPUT control to 11 o’clock. (Input source Z= 150 Ohms, Output load Z= 100 kOhms)
• Maximum input level: (1 kHz Sine, <0.3% THD+N)
  • -3 = +25 dBu
  • 0 = +21 dBu
  • +3 = +18 dBu
• Maximum GAIN: 13dB
• GAIN makeup: 10dB (gain above unity)
• Output Headroom: 23dB (referenced to +4dBu)
• Variable ATTACK control: 13msec - 130msec
• RECOVERY switch 5 steps: 0.1s, 0.16s, 0.32s, 0.64s, 1.7sec.
• Continuously variable THRESHOLD controls
• Hardwired Relay Bypass Switch
• Ratio Mode switches between LIMIT (1.5:1 to 12:1) or COMPRESS (1.2:1 to 3:1)
• HP SC: High Pass Side Chain Filter -3dB @ 100Hz @ 6dB per Octave
• Stereo Link establishes Left-Master dynamic control for THRESHOLD, ATTACK, and RECOVERY controls
• Beautiful illuminated stereo VU meters read Gain Reduction or Output Level

• Sidechain INSERT per channel via 1/4" TRS jack TIP=SEND, RING=Return, SLEEVE=Ground
• Maximum Output: +27dBu (18Vrms) into 100K Ohm load; +24.5dBu (13Vrms) into 600 Ohm load. (1Khz Sine, < 0.3% THD+N, BW 20Hz - 20kHz).
• Frequency Response: - 0.8dB @ 20Hz, -0.5dB @ 50kHz
• Total Harmonic Distortion: <0.05% THD+N (1kHz Sine, +4dBu, BW: 20Hz - 22kHz)
• Noise floor: -85dB typical (BW: 20Hz - 22kHz)
• Dynamic Range: 112dB
• Signal to Noise Ratio: 89dB (referenced to +4dBu)
• Common-Mode Rejection Ratio (CMRR): 74dB (BW: 20Hz - 22kHz, +4dBu, 1kHz Sine)
• Transformerless Impedance-Balanced Output Impedance: 100 Ohms
• Input Impedance: -3dB= 1 kOhms, 0dB= 2.5 kOhms, +3dB= 4.5 kOhms
• AUTOMUTE warmup delay: 30 Seconds
• Power consumption: 35 Watts
• Standby Power Consumption: 0.5 Watts
• Operating mains voltage: 90 to 254 VAC (internal universal supply)
• Mains Voltage Frequency: 50-60Hz
• Dimensions: 19" x 3 1/2" x 7" (occupies 2u)
• Unit Weight: 8.5 lbs.
• Shipping weight: 11.5 lbs.

The Nu Mu is a modern interpretation of our classic Variable Mu. While both units feature the unique "remote cut-off" tube compression design and the "T-Bar" modded input stage, the Nu Mu replaces the all-tube output stage of the Variable Mu with a discrete solid-state circuit. This hybrid design gives the Nu Mu a different sonic signature: it is faster, cleaner, and more transparent, while still retaining the rich, warm character of the tube input. It provides the musicality of a variable-mu compressor with the punch and clarity of a modern solid-state unit, making it exceptionally versatile for contemporary music.

The Manley HIP® control is a unique feature that intelligently applies more compression to the lower-volume parts of a signal while leaving the louder, more dynamic peaks largely untouched. This function effectively raises the average level and density of a track, bringing out subtle details and adding a finished polish without "squashing" the loud parts. It's an elegant solution that achieves a similar effect to parallel compression—often with a better, more natural result—but in a single, easy-to-use knob.

The Nu Mu is exceptionally versatile and is a fantastic tool for a wide range of sources. Its unique hybrid design and transparent performance make it ideal for modern genres that require clear, punchy transients. It shines on the stereo mix bus, adding glue, density, and that signature analog warmth. It also excels on individual tracks like drums, bass, and vocals where its smooth compression and ability to add "sizzle" to the high end and "fullness" to the low end can be used for creative tone shaping.

Yes, the Nu Mu is a superb tool for mastering. It was designed to add a final layer of polish and density to a stereo mix. The transparent compression, high headroom, and musical character allow mastering engineers to increase the perceived loudness and detail of a track without sacrificing dynamics or adding unwanted distortion. The stereo link function and the unique HIP® control are particularly useful for mastering applications, providing precise control over the overall dynamics of a stereo file.

The Nu Mu features a total of four hand-matched 6BA6 vacuum tubes. These tubes are part of the Variable Mu-style input gain reduction stage, which is the heart of the unit’s compression circuit. They were chosen for their excellent gain reduction characteristics and their ability to impart a smooth, musical warmth to the signal before it reaches the solid-state output stage.

The Nu Mu features a switch that allows you to toggle between two distinct ratio modes: COMPRESS and LIMIT. In the COMPRESS mode, the ratio is a smooth, gentle 3:1. In the LIMIT mode, the ratio becomes a more aggressive 10:1. The unit's compression curve is variable, meaning the ratio changes dynamically as the signal goes deeper into gain reduction, providing a natural and musical response rather than a fixed, hard-knee effect.