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173.623 (Vivanco EM216) stereo tie-clip microphone specifications

The 173.623 tie-clip stereo electret condenser microphone is quite cheap (about EUR 36) and sold by various electronics resellers, such as Skytronic, Tandy, Sound Lab (Soundlab, model G157B), Vivanco EM 216, apparently only in Europe. I bought one in The Netherlands. The supplied specifications are minimal, so I decided to measure the frequency characteristic myself after I noticed that the basses were really weak. So there:

Specifications according to manufacturer

Sensitivity(*)	-68 dB (+/- 3 dB)
Impedance	2000 ohm
Frequency range	20-16000 Hz
Transducer	Twin omnidirectional electret condensor

(*)Sensitivity is probably relative to 1V, 1 mu-bar. See manufacturer's site.

The specified frequency range is `somewhat' exaggerated. For a reasonable sound reproduction, the curve should be flat (within +/-3 dB) in the range 100--12000 Hz. This microphone behaves rather as a 4 dB/octave high-pass filter with a cut-off at 2.5 kHz. Moral: never trust frequency range specifications for microphones unless you get a curve. By the way, a frequency response range for a microphone means nothing more than that every individual microphone should have a response curve that differs no more than +/-2.5 dB from the specified response curve. The latter need not be flat.

If we convert the specifications to the more common notation, we get:

Sensitivity	-48 dB (at 1 Pa, re. 1 V = 0 dB)
Frequency range	500-11000 Hz

Measurement details

The microphone was suspended at 64 cm in front of a loudspeaker in an echo-free situation (i.e. my loudspeaker in the window and the microphone suspended outside my apartment on the third floor). The microphone was in mono mode, "LR" symbol towards loudspeaker, and connected to a portable Sharp MD player and then to a mixer panel. I used the VU meters in combination with the fader to measure the signal level. As a reference microphone, I used a Stagg MCO-7 large-membrane condensor microphone in omni-directional mode, which has a reasonably flat response between 20-20000 Hz. The sound source was a test cd with sine waves at various frequencies.

Recommendations

For its price, it is not too bad. Its frequency response might actually be an advantage for its intended purpose as a lapel microphone recording speech. However, for recording music: the stereo effect is rather weak and the recorded sound will be colored. The human ear does a suprisingly good job at ignoring the latter, though. If you want to record live music, with an MD or MP3 recorder, I'd recommend to order a pair of miniature microphones from Sound Professionals, that you can plug in directly into the MD player (with a plug-in-power connector). Use cardiods if you intend to mount them on a stand, or omnidirectionals if you will carry them. Even though their web site is horrible, I'm happy with the mikes I bought there. (The microphone mounts suck, though) I am not affiliated in any way to them. A

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