Field Report: RDL HR-MCP2

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Radio engineers are sometimes regarded as control freaks. And for good reason: An engineer spends each day critically listening to and adjusting the audio chain in his or her facility. The aural characteristics of a studio are somewhat of a signature for the engineer. He or she will generally take ownership of the technology and the sound that is crafted. The continual mulling-over of audio is the sure sign of a dedicated engineer and the negative “control freak” connotation contains a slight pat on the back.


For control freaks, Radio Design Labs (RDL) has introduced the HR-MCP2 dual-channel microphone compressor. The unit takes up half a single rack space, and the dynamic control packed inside it is an overly picky engineer’s dream come true.

Making the connections

The HR-MCP2 is designed to be portable or permanently installed. A standard plug-in jack and a Phoenix-style terminal block facilitates the 24Vdc power input from the wall-wart power supply. The unit draws 200mA during normal use or 230mA when phantom power is used. Both microphone inputs have XLR inputs and outputs as well as terminal block inputs and outputs. Output levels are set to either line or mic using rear panel recessed switches on both channels. The mic-level outputs allow for the compressor to be set up in-line between the microphones and mixing console inputs. When line-level output is used, the unit can be output to a line-level console input or channel insertion point.

As simple as 1-2-3

Both channel adjustments, except for line/mic output selection, are made via the front panel. Each channel has a 6dB/octave low cut filter with a 3dB cutoff at 80Hz. “Gain” facilitates 20dB to 60dB of microphone gain adjustment along with a 15dB input pad that compensates for high-output condenser mics. Each channel has a single red LED clip indicator and a seven-segment LED meter that displays gain reduction in 3dB increments. The phantom power on/off button provides 48V for both channels. The power button is ganged with a bright blue LED that is illuminated when the unit is powered on.

Performance at a glance
■ Transparent control of dynamics
■ Two channels of compression in 1/2 1RU space
■ Phantom power, low cut filter and 15dB pad
■ Super-low noise floor
■ Up to 25dB of compression

Proper operation of the HR-MCP2 requires minimal, but important level setup. By way of a brief example, I used a standard large-diaphragm condenser microphone and put the compressor in-line between the microphone and a mic input on a production mixing console. With low-cut filter and input pad on, I raised the gain until my normal speaking voice produced 9dB of gain reduction. The red LED clip indicator will flash slightly prior to any audible clipping. For best performance, the clip LED should never flash. The results of this particular setup are discussed in the next section.

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