The MU524 is a compressor where the gain variation is provided by varying the mu (gain) of a special tube.

With the help of two transformers it provides a smooth and natural soft knee compression which can travel into land of distortion when driven hard.

It is a professional-grade unit that brings the warmth and character of vintage gear to the 500 series world.

Install it in your API* compatible Lunchbox^TM rack and start working.

Highlights

• Based on classic vari-mu compressors like Altec 436 / RS124,
• Natural soft knee compression,
• Great on single instruments, brilliant on full mixes,
• Balanced dual triode design,
• New, old stock (NOS), remote cut-off tube,
• Two Transformers in the audio path,
• Illuminated SIFAM meter,
• Optional High pass filter in the sidechain,
• Two units can be linked for stereo,
• Hardware relay bypass,
• Available assembled or as a full kit.

Controls

1: IN/BYPASS/LINK

• IN (left): Compressor active,
• BYPASS (center): Hardware relay bypass,
• LINK (right): Compressor active and stereo link connected for stereo operations.

2: METER Shows the gain reduction from 0 to -20dB.

3: IN Sets the input level to the compressor which also defines the threshold at which the compression appears.

4: LIMIT Increases the compression ratio to a limiting level.

5: OUT Sets the makeup gain of the compressor.

6: HPF Inserts a high-pass filter in the sidechain which produces a fat sound and eliminates bass driven pumping.

7: REC. Recovery sets release time of the compressor.

8: FAST ATTK Shortens the attack time of the compressor.

What's in the kit?

Absolutely everything!

• Passive components (resistors, capacitors, inductors),
• Transformers,
• Active components (tube, diodes, transistors, IC's),
• Control elements (meter, switches, potentiometers, knobs),
• Connectors, relay,
• PCB's,
• Front panel and side panels,
• All hardware.

You bring the solder (use good quality solder, 1mm diameter max) and the Lunchbox.

Difficulty level

The MU524 kit is a medium difficulty kit. It can be undertaken by anyone who is able to make a clean solder joint.

The setup is a little more complex than average. It requires a good quality digital multimeter.