Shure M68-RM (1969 – [VERIFY: end year not confirmed])
Four mic inputs, one reverb control, and a lot of small club PAs in the early '70s.
Overview
The M68-RM is the reverb-equipped member of Shure's M68 mixer family. It is a solid-state four-channel microphone mixer with built-in reverberation, announced in late 1969 at $180.00 according to Audio (October 1969, p.18). The pitch was simple. Shure already had the portable-mixer formula working in the plain M68, so it added a reverb control for vocalists who wanted some space on their voice without hauling a separate echo unit. Target buyers were working bands and small house-of-worship PAs.
The channel layout is the interesting part. Each of the four microphone inputs gets its own volume control and its own slide switch to select high or low impedance. That helped when a band showed up with a mix of high-Z and low-Z mics and no patience for matching transformers. One of the four channels can double as an auxiliary high-level input, which is how owners fed a tape deck or a second source into the same mixer. A master gain control sits above the individual channel volumes and moves all four inputs together, so you set your balance once and ride the whole mix from one knob.
The reverb is the reason the RM exists. Shure advertised it as built-in reverberation "for vocalists and special effects," and Recording-Engineer (April 1972, p.48) ran that copy as part of a seven-product Shure mixer lineup. It's marketing, and it tells you who Shure thought the buyer was: the singer who wanted a little ambience, or the small act that wanted effects without a rack. It does not say how the reverb sounds, how deep the tank is, or how noisy the circuit runs. No independent bench test of the M68-RM turned up in the available material. Owners describe a spring-style ambience that's serviceable on voice and obvious on anything percussive, but that's the sound of the category, not a measured claim.
The period record does confirm the price and the positioning. The October 1969 Audio announcement put the M68-RM at $180.00. By the early '70s the UK distributor Rosetti & Co. was listing the M68RM-2E reverberation mixer at £63.60, with the non-reverb M68 FC-2E at £48.60. That's a roughly fifteen-pound premium for the reverb. The plain M68 was the volume seller, and the RM was the step up for anyone who wanted the effect built in.
The used market was active. By 1971-73, M68-RM units were showing up regularly in the classified pages of Audio at $70 - $80, roughly half their new price within a few years. One seller in Abilene was moving an M68RM alongside M67 Promixers and an M63 Audiomaster. These mixers were bought to be used, sold when the gig changed, and bought again by the next buyer.
The M68-RM is a solid-state unit from the era when Shure's portable mixers were the default answer for anyone who needed four mics into one output without a console. The metal case and the slide switches define the feel: positive and slightly stiff. Collectors note that the slide switches and the reverb control are the usual wear points on a fifty-year-old example. A unit that's been in a road case will often have one channel switch that's gone scratchy or a reverb pot with a dead spot. That's maintenance, not a design flaw, but check it before you hand over money.
For a collector of Shure's mixer line, it's a clean example of the company's late-'60s portable approach, and it sits alongside the M68, M67, and M63 in a display of the "Magnificent Seven" family that Shure advertised heavily in the trade press. For someone who wants to mix four mics today, the high/low impedance switching and the master gain are still sensible. The reverb is a flavor rather than a tool. No noise or frequency-response figures are documented, so you're buying on reputation and condition rather than on a spec sheet.
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