Locomotive Audio POWER-MU 500 – 500 Series Stereo Vari-Mu Compressor

OVERVIEW

A Full-Featured Stereo Vari-Mu Compressor for 500 Series – The Perfect Companion for Your Stereo Bus

The Locomotive Audio POWER-MU 500 brings the unmistakable sound of tube vari-mu compression to the 500 series format. Designed as a stereo bus companion, it excels at delivering smooth, musical compression while enhancing your mix with warmth and harmonic character. With stepped 21-position controls, you can easily recall sessions with precision, making it both powerful and practical for modern workflows. Whether applied subtly for glue or pushed harder for saturated dynamics, the POWER-MU 500 offers the versatility to handle any mixing or mastering task.

At the core of its design are custom interstage transformers and a pair of NOS dual triode tubes, ensuring authentic vari-mu response with no harsh artifacts. Independent AC and DC threshold controls let you fine-tune when compression begins, how the knee responds, and how much harmonic drive is introduced. Features like a sidechain low-cut filter, stereo link switch, and hardwire bypass make it an indispensable tool for achieving professional, polished results. Hand-built in the USA with rugged construction and lifetime support, the POWER-MU 500 is built to inspire confidence in every session.

The Power-Mu Experience

Full control of gain staging, harmonics, compression threshold, and ratio is at the heart of the Power-Mu experience. Input and output controls allow you to decide how much audio level you would like to send through the unit. The AC and DC threshold controls determine when compression kicks in and what kind of compression knee is obtained. Lower DC threshold settings will have a softer onset of compression, while higher DC threshold settings will have a harder knee with limiting characteristics.

KEY HIGHLIGHTS

TRANSFORMERS:

Custom interstage transformers allow for smooth compression without harsh artifacts.

AC & DC THRESHOLD:

These threshold controls work together to set compression onset, knee, and ratio, giving abundant control over tube drive.

TUBES:

Each channel uses a NOS dual triode for true vari-mu compression and tube harmonics.

SIDECHAIN LOW CUT:

Cut low frequencies from the sidechain in order to prevent unwanted compression.

STEPPED CONTROL:

The stepped 21-position knobs on the Power-Mu allow for performances to be recalled with precision.

HARDWIRE BYPASS:

This switch allows the user to toggle between the original and affected signals

STEREO LINK:

Force the same gain reduction on the left and right channels to stabilize the center image.

POWER SWITCH:

Save tube life and 500 series chassis power by turning off the power when not in use.

FEATURES

• Stereo Link switch
• Sidechain Low Cut filter control: Off-350Hz
• Hard-wire bypass switch​​​​
• Two-position VU meter switch: Gain Reduction – Output​​
• Custom Sifam backlit VU meter
• Custom interstage transformers
• Hand-built in the USA
• Heavy 16-gauge steel chassis​​​
• Lifetime warranty on parts and labor

TECHNICAL SPECS

Tubes: (2) NOS 6N3P

Input Load Impedance: 22kΩ

Output Impedance: < 100Ω

Variable Attack: (10 mS – 75 mS)

Variable Release: (150 mS – 1.5 Sec)

AC & DC Threshold Knobs

Frequency Response: 20Hz-20kHz

THD+N: < 1%

S/N Ratio: > 70dB​​

Power Consumption: +16v=300mA, -16v=400mA across both spaces​

Dimensions: Doublewide 500 Series

Shipping Weight: 5 lbs.