Neumann KM 56
A miniature condenser that Neumann's own advertising placed at the top of its precision line. The company later called it the crowning achievement of the KM50 series.
Overview
The KM 56 is a small-diaphragm condenser microphone from Neumann's KM50 series. The paper trail on it is unusually good for 1950s studio gear. Neumann's own advertising in the late 1950s billed it as the latest addition to the company's precision line, with quality "in every way similar" to the U-47 series but in dimensions the copy called amazingly miniaturized. It was never pitched as a budget alternative to the big studio tube mics. It was pitched as the same caliber of tool in a housing you could actually position.
The capsule is where the KM 56 gets interesting. A 1980 retrospective in Recording-Engineer (February 1980, p.88) describes the problem Neumann faced. Shrinking the capsule to 15 mm in diameter meant the old technology could no longer meet the performance expectations set by the larger mics. Keeping a high signal-to-noise ratio with a smaller capsule required new thinking. The piece credits the KM 56 as the crowning achievement of the KM50 series, where Neumann pushed the design one step further than the rest of the line. The same article notes a material shift underway at the time: DuPont's Mylar film could be tensioned farther than the original PVC membrane and offered real advantages over it.
Nickel membranes are the other half of the KM 56's identity. Neumann's promotional material for the follow-up KM 88 describes that model as a deliberate continuance of the KM 56 sound. It specifically calls out the all-nickel membranes as producing a brilliance unavailable from Mylar capsules. Neumann was adopting Mylar elsewhere while marketing the nickel capsule as a distinct, desirable sound the company wanted to carry forward rather than replace. Collectors who have spent time with both capsule types tend to describe the nickel sound the way the advertising did: present, detailed, not soft.
The KM 56 is documented in Audio (June 1959, p.36) with a frequency response of 40-15,000 cps ±3 db. For a miniature of the period, that range was the whole argument for using it on sources where a full-size mic wouldn't fit. Output impedance had to be specified at order time, either 50 or 250 ohms, so these were built to order rather than pulled off a shelf. The power supply was a separate box, 8½" x 4" x 4¾". The pattern was switchable on the microphone itself between non-directional, bi-directional, and cardioid.
That on-body pattern switching set the KM 56 apart. A miniature with three remotely selectable patterns was not a common combination, and the fixed-pattern small condensers that came later didn't have it. It also makes original examples harder to find in working order today. More switching, more to go wrong.
By the early 1960s Neumann was running the KM 56 in full-page advertising alongside the KM-54a, under the line that Neumann condensers were "the standard against which all others are compared." The KM-54a and KM-56 were shown as the two miniature options in the range. The KM-54a was positioned separately as a hyper-cardioid miniature designed with TV and film in mind, advertised at $410. The continuously variable directional pattern system in the same campaign carried a $495 figure. Contemporary listings placed the KM 56 itself at $450 in the used market by the late 1980s.
A 2001 Studio-Sound (July 2001, p.66) masterclass on Neumann model codes notes that valve microphones with three-digit type numbers prefixed by a "2" follow a consistent naming rule. That helps place the KM 56 within Neumann's broader catalog logic. The same piece describes the maintenance reality: when spares became unavailable, engineers took to fitting small single-diaphragm fixed figure-8 capsules into KM 56 and KM 88 bodies to keep the microphones in useful condition. So the original capsules are the failure point, and a working KM 56 today may or may not have its original capsule inside it. Buyers should ask.
The used-market record also shows the KM 56 circulating through professional broker listings well into the late 1980s and early 1990s, typically in the microphone section alongside KM 84s and other Neumann small condensers. It was a working tool in that era, bought and sold by studios that needed small, pattern-flexible condensers.
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