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MC2      Microphone Combining Box



  • Combines 2 Low-Z Microphone Signals
  • Ideal for Recording and Live Sound
  • Use for Backup Microphones at Press Conferences and Speeches
  • Connects with Standard Microphone Cables
  • Polarity Reversing Switch Corrects Phase Cancellation
  • High Quality Transformer-Isolated Output
  • Rugged ProCo Uni-Box Construction Provides Protection and EMI/RFI Shielding



The ProCo TradeTools MC2 Mic Combiner passively combines the signals from two low-impedance microphone (or similar sources) into a single output. It is a handy “band-aid” for situations where the number of microphones required exceeds the number of mixer channels available, but separate equalization and level control for every microphone is not required. In a musical or recording situation, the MC2 can combine mics from sources like dual bass drums, percussion, stereo guitar amps, etc. Commercial sound uses include combining dual mics on a public speaker for redundancy and handling extra mics for audience participation at meetings. The MC2’s transformer isolation minimizes interference from EMI/RFI and ground loops, retaining the advantages of common-mode noise rejection inherent in the use of balanced lines.

The MC2 is fitted with standard 3-pin XLR-type connectors for INPUT 1 and 2 and OUTPUT, so hookup requires only standard microphone cables. One input is provided with a REV/POL switch to change its polarity. This is very useful for correcting acoustical or electrical phase cancellation problems such as poor mic placement. The use of the ProCo MBT-2 transformer allows the MC2 to provide a floating, low-impedance output with wide, flat frequency response, ultra-low distortion, and no ringing or overshoot to degrade transient response.

The MC2’s ruggedly constructed “Uni-box” enclosure is formed of extruded aluminum side channels and 16-gauge steel top, bottom and end plates and is designed to protect switches and connectors from accidental damage. The use of steel also provides excellent magnetic shielding for the transformer from EM/RF fields. Top-quality connectors and switches provide trouble-free service even in abusive situations such as remote broadcast and recording operations.


All measurements made with 150Ω source feeding INPUTS and 1.0 kΩ load on OUTPUTS to simulate typical "real world" microphone and mic preamp. 0 dBv ref. = .775 volts.
NOTE: Phantom power (if required) must be supplied by suitable power supply connected directly to microphones before MC2 INPUTS.

Frequency Repsonse:

20 Hz - 20 kHz, ± .5% @ -15 dBv output.
-3 dB @ approximately 230 kHz.

Total Harmonic Distortion:
<.03% 20 Hz - 20 kHz @ -30 dBv output.
<.1% 30 Hz - 20 kHz @ -15 dBv output.
<.25% 20 Hz - 20 kHz @ -15 dBv output.

Voltage Loss:

<7.0 dB @ 1.0 kHz.

Input Impedance:
>235 Ω @ 1.0 kHz.
>185 Ω @ 10kHz.
Nominal source impedance is 150 Ω.

Output Impedance:
<180 Ω @ 1.0 KHZ.
<300 Ω @ 10 kHz.
Nominal output impedance is 1.0 kΩ.

Maximum Input Level for 1% THD:
0 dBv @ 20 Hz.
+4 dBv @ 30 Hz.
+8 dBv @ 50 Hz.