The MXR Model 136 Dual Limiter is a rare, vintage 1U rackmount processor from the 1980s. While MXR is primarily known for stompboxes, this unit is a cult favorite in studios for its aggressive character and unique internal design.

Key Technical Specs

• Circuitry: Unlike most compressors of its era that used VCAs or FETs, the Model 136 uses Pulse Width Modulation (PWM). This esoteric method chops the audio into ultrasonic slices to control energy, resulting in a very fast, distinct sonic footprint.

• Channels: Dual-channel design that can operate in Dual Mono or Stereo Link modes.

• Controls: Each channel features independent knobs for Input, Output, Attack, and Release.

• Ratio: A simple push-button toggles between 4:1 (Compression) and $\infty$:1 (Brick-wall Limiting).

• I/O: Professional connectivity including both XLR and 1/4" TRS inputs/outputs, plus dedicated Sidechain inserts for external keying.

Sonic Character

The Dual Limiter is often described as a "color" compressor rather than a transparent one.

• "The Poor Man’s 1176": It is frequently compared to the UREI 1176 due to its lightning-fast attack and ability to "grab" a signal aggressively.

• Gritty and Dark: It tends to add a grainy, "raunchy" texture to audio. It is highly prized for "destroying" drum rooms or adding attitude to aggressive vocals.

• Instant Lo-Fi: Because it can distort nicely when slammed, some producers use it specifically as a grunge or lo-fi effect rather than a utility leveler.

Maintenance Notes for Collectors

If you are looking at a vintage unit, there are a few common "era-specific" quirks to keep in mind:

• Heat Issues: The internal voltage regulators run very hot, which often leads to dried-out capacitors over several decades. Most reliable units on the market today have been "recapped" to prevent failure.

• XLR Wiring: Some older units were manufactured with Pin 3 Hot, which differs from the modern standard of Pin 2 Hot. You may need to check the wiring if you experience phase issues in a modern studio setup.

Pro Tip: One of the most famous "tricks" with this unit is cascading the two channels in series—using the first channel for fast peak limiting and the second for slower, musical compression.