The MSH-4 was discontinued in November 2007.

The X-V tube microphone kit uses the 6418 tube in an improved circuit.

The MSH-4 is a transformerless, phantom-powered, tube-driven omnidirectional small-diaphragm microphone. Inside is a subminiature tube (Raytheon JAN 6418) which imparts a pleasant character to the sound. To maximize dynamic range and the sonic enhancement of the tube, place the MSH-4 close to the source, even within 12 inches (30cm). Unlike cardioid microphones, the omnidirectional MSH-4 does not have increased bass response due to proximity effect. The MSH-4 retains a natural response regardless of source distance.

The maximum level of the microphone is rated at 112dBSPL; at that level, higher-order distortion begins to increase. The MSH-4 will not be harmed by higher levels, however, the signal may be clipped.

With the subminiature tube in a small case, the MSH-4 is vulnerable to handling noise («microphonics»). When using your MSH-4, it is highly recommended that a padded clip or a shockmount be used. Switch on phantom power after the mic is mounted, and allow at least 3 minutes for the tube to warm up and the microphone to settle. To reposition the MSH-4, switch off phantom power, reposition, turn phantom power back on, then allow another 2 or 3 minutes to for the microphonic noise to completely subside.

The MSH-4 requires a +48V phantom power supply that is capable of supplying 10mA per microphone, according to DIN standard 45 596/IEC standard 268-15A. The MSH-4 will function poorly or not at all when connected to a nonconforming power supply.

MSH-4v2 Specifications

Type: 10mm omnidirectional electret condenser tube microphone
Phantom Power: +48V @ 10mA current per microphone required
Current: 9mA
Recommended Input Impedance: 1KΩ minimum
Sensitivity, 1kHz @ 94dBSPL: -36dBV/Pa
Total Harmonic Distortion, 1kHz @ 94dBSPL: 1% typical
Maximum Recommended Level: 112dBSPL
Frequency Response: 100Hz to 16kHz
Polar Response, 180°: -3dB @ 10kHz
Self-Noise: 23dBA
Weight: 1.8oz (50g)
Dimensions: 2 13/16″ x 3/4″ø (72mm x 19mmø)

MSH-4v1 Specifications

Type: 6mm omnidirectional electret condenser tube microphone
Phantom Power: +48V @ 10mA current per microphone required
Current: 9mA
Recommended Input Impedance: 1KΩ minimum
Sensitivity, 1kHz @ 94dBSPL: -32dBV/Pa
Total Harmonic Distortion, 1kHz @ 94dBSPL: 1% typical
Maximum Recommended Level: 112dBSPL
Frequency Response: 20Hz to 20kHz
Polar Response, 180°: -3dB @ 10kHz
Self-Noise: 22dBA
Weight: 2.3oz (66g)
Dimensions: 3 3/8″ x 3/4″ø (85mm x 19mmø)