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MS43A      4 Channel (3 Way) Rack Mount Mic Splitter


  • Provides 3-way Split for Low Impedance Microphone
  • 4 Splitter Channels in Single Rack Space
  • Allows Assembly of Economical Expandable Splitting System
  • Great for Musicians' Monitoring and Recording
  • Uses Include Press Conferences and Speeches
  • Connects with Standard Microphone Cables
  • High Quality Transformer-Isolated Output
  • Rugged ProCo Uni-Box Construction Provides Protection and EMI/RFI Shielding


The ProCo TradeTools MS43A Quad Mic Splitter splits the signals from each of four low-impedance microphones (or similar sources) into three outputs, enabling three microphone preamplifiers to be fed from one source. The primary application for the MS43A is in large sound reinforcement systems, where the P.A. system microphones must also be fed to a stage monitor system and a broadcast or remote recording mixer. In such complex systems grounding problems can cause both unacceptable noise levels and severe shock hazards. Transformer isolation in such situations minimizes interference from EMI/RFI and ground loops. The transformer-isolated feeds retain the advantage of common-mode noise rejection inherent in the use of balanced lines.

The MS43A is fitted with standard 3-pin XLR-type connectors for MIC IN, DIRECT, and ISO OUT 1 and 2, so hookup requires only standard microphone cables. The use of the ProCo MBT-2 transformer allows the MS43A to provide floating, low-impedance outputs with wide, flat frequency response, ultralow distortion, and minimal ringing or overshoot to degrade transient response. The transformer’s triple electrostatic shields and GND/LIFT switches provide isolation and buzz-free operation in virtually any environment.

The MS43A’s rugged 16–gauge steel and aluminum “Uni–box” enclosure is finished in a durable black texture powder coat finish with black anodized aluminum side channels. Easy–to–read control graphics are incorporated into the Lexan® front and back panel overlays. Inside, the specially designed transformers combine superb audio quality with unsurpassed noise rejection.

The MS43A can be mounted in any standard 19” (482.6mm) rack. Top quality connectors and switches provide trouble-free service even in abusive situations such as remote broadcast and recording operations. The rack-mounting design allows the user to assemble a conveniently packaged, expandable splitting system that combines top quality audio performance and isolation with an economical price.


All measurements made with 150Ω source feeding MIC IN and 1.0 kΩ loads on ISO OUTS to simulate typical "real world" microphone and mic preamps. 0 dBv ref. = .775 volts.
NOTE: Phantom power (if required) must be supplied by mixer (or suitable power supply) connected to DIRECT.

Frequency Repsonse:

20 Hz - 20 kHz, ± .25% @ -15 dBv output.
-3 dB @ approximately 140 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.
Phase Response:
<-13 degrees @ 20 kHz (ref. 1.0 kHz).

Rise Time:
<2.4 microseconds (2.0 kHz square wave, 10%-90%).

Voltage Loss:

<2.5 dB @ 1.0 kHz.

Input Impedance:
>570 Ω @ 1.0 kHz.
>570 Ω @ 10kHz.
Nominal source impedance is 150 Ω.

Output Impedance:
<255 Ω @ 1.0 KHZ.
<270 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.