Sennheiser MD-409
A rectangular dynamic that engineers kept clipping to guitar amps and rack toms - and that one magazine thought was worth a full restoration guide.
Overview
The MD-409 is a supercardioid dynamic microphone with a rectangular body. The shape is the whole point. A period survey of Sennheiser's range in Beat Instrumental described the MD 409 as a supercardioid suitable for both musicians and vocalists. EQ Magazine (April 1999, p.54) singled out its shallow, flat profile as the reason it could be slipped in front of a guitar amp without a stand, or squeezed between a rack tom and a low-flying cymbal. A conventional round-bodied dynamic is much harder to place in a tight drum kit.
The same survey noted an advantage for vocalists: no low-frequency resonance, plus a built-in noiseless switch and a wide frequency range. For a handheld dynamic, that matters in practice. The mic does not thicken up into mud when a singer works it close, and the engineer has less to fix at the console. Sennheiser's own copy in that survey described the present range of electrodynamic microphones as the result of research into how professional singers, bands, and television users were already putting the company's high-fidelity mics to work.
In practice the MD-409 was a working mic. Trade-press gear lists from the period show it doing unglamorous jobs in real rooms. A Mix (June 1987, p.32) session layout lists the MD 409 on rack tom 3, floor tom 1, and on both the Francis and Asante congas. A studio news item in Recording Engineer records Heavenly Recording Studios in Sacramento adding a single MD-409 to a mic locker that otherwise ran to a Neumann U-47 FET, an AKG C-34, and a Crown PZM-31. A live-sound rig rundown from the same publication places the MD 409 on guitar No. 1, with an MD 421 on guitar No. 2 and MD 421s across the kick and toms.
EQ Magazine (April 1999, p.54) ran a full restoration feature on the MD-409. It walks readers through fixing a classic example - the connector, the on-off switch, and a tapped pivot that screws directly onto a Euro-style mic stand. A 1999 trade magazine does not write a restoration tutorial for a mic nobody owns.
The available documentation does not establish the original list price, the production start and end years, or a catalogued set of common failure modes. Used examples circulate, but the source material has no reliable current market pricing or parts-availability information, and none should be assumed.
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