Schoeps CMT-56
A side-address pencil condenser that reviewers struggled to find fault with, and that one engineer nearly lost to the Spanish dew.
Overview
The CMT-56 is a phantom-powered capacitor microphone from Schalltechnik Dr.-Ing. Karl Schoeps of Karlsruhe. It's a side-address design - the capsule picks up from the side of the body rather than the top - built into a slim pencil-style housing roughly the size of a Calrec CM 1050 or AKG C452. It connects via standard XLR three-pin, and it offers cardioid, omnidirectional, and figure-of-eight patterns. The patterns aren't switched electrically the way a double-diaphragm design does it. They're selected mechanically, by twisting the mic cap through click-stops for each position.
The CMT-56 differs from its sibling, the CMT-36, in the electronics. Both are phantom-powered, but the CMT-56 runs on 48V while the CMT-36 is a lower-voltage design. The CMT-56 uses a single FET whose drain feeds the primary of an output transformer through an electrolytic decoupling capacitor, so it's a transformer-coupled amplifier. The CMT-36 omits the output transformer entirely. Schoeps' published specification for the CMT-56 puts the frequency range at 40 Hz to 16 kHz, output level at −38 dBV per 10 dynes/cm² in cardioid, and sensitivity at 1.2 mV/dyne/cm². Source impedance is approximately 200 ohms symmetrical, and it wants to see a load greater than 600 ohms. It draws only about 650 µA, which helps if you're hanging a pair off a single supply.
The noise numbers are good. Schoeps rated equivalent noise loudness at approximately 23 dB SPL (CCITT) for the CMT-56, with noise voltage around −110 dBV. Both figures are a few dB better than the CMT-36's 26 dB SPL and −106 dBV. Maximum SPL at 0.5% THD into a 1 kΩ load is quoted at 126 dB for the CMT-56, against 128 dB for the transformerless CMT-36. So the transformer-coupled version gives up a couple of dB of headroom for a lower noise floor.
Studio Sound (January 1975, p.52) put the CMT-36 and CMT-56 through a blind comparison against an AKG C414 and a Neumann U87, recording identical material to separate tracks of 38 cm/s Dolby A tape and switching between mics without the listeners knowing which was which. The reviewers, Angus McKenzie and Tony Faulkner, came away describing the Schoeps pair as extremely flat with no particular coloration, and they noted that the two Schoeps models didn't differ noticeably in sound quality across any of the tests. The polar diagrams, they reported, were audibly good — the figure-of-eight especially — and a coincident Blumlein pair of the mics produced stereo imaging that put multi-mic balances to shame. On a madrigal recording the words came through clearly with a very good extreme top and no excessive rumble from London Airport. Headphone monitoring apparently had them turning around mid-session, convinced someone was in the room talking.
What the Schoeps didn't do, per the same review, was flatter. The string tone was clear and true but lacked the "flattering" character of the C414, and brass lacked the vividness of the U87. The reviewers suggested channel EQ could close that gap.
The one reliability anecdote comes from that same piece. A UK user named Bob Woolford reported a single difficulty. He was recording outdoors on an island off Spain, and a late-night session broke off around 4 a.m. When he came back, the microphones were behaving badly. The cause turned out to be a heavy accumulation of dew. Wiped off carefully, everything returned to normal.
On pricing from the period, Schoeps' own specification sheet listed the pair at £195 and £187. By the end of the decade the CMT-56 was still turning up in professional studio inventories. A 1980 Mix studio listing names it alongside Neumann U-47s and KM-84s.
For collectors, the CMT-56 is a working tool more than a trophy. It's the transformer-coupled half of a pair that reviewers could not separate by ear. The mechanical pattern cap is the wear point to inspect on any example, and the 48V-only powering means it won't run off the lower-voltage supplies some older gear provides.
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