Shure "300" Multi-Impedance Gradient Broadcast Microphone
A studio ribbon mic from the golden age of radio, priced at $135 when that bought a lot of console radio - and still flat to 15,000 cycles.
Overview
The Shure "300" is a studio-grade broadcast microphone built around a metallic ribbon suspended between the poles of a magnet. It's a velocity microphone, not a moving-coil dynamic. It measures 40 to 15,000 cycles, and the period test bench found it flat all the way out to the top of that range. Ribbons have a reputation for rolling off up top. This one doesn't.
Collectors like the 300 for its impedance flexibility. Shure shipped it with the components needed to rewire it for 30 to 50 ohms, 150 to 250 ohms, or high-impedance inputs. That covers low-Z broadcast lines, mid-Z studio gear, and high-Z home recorders in one microphone, which is why it turned up in radio stations, TV studios, and serious home taping rigs alike. A voice-music switch doubles as a low-frequency boost, giving maximum body for spoken word when you flip it over.
The pickup pattern is bidirectional - figure-8 - with equal sensitivity front and rear. Shure's own documentation is blunt about where that pays off: dual-operator setups on a stand, close work on a desk mount, under a grand piano, and PA systems where you want the rear lobe working for you rather than against you. The shock-mounted swivel base is live rubber, which keeps floor vibration and mechanical rumble out of the ribbon. The whole assembly is built to handle humidity and temperature swings.
Output level averages about −59 dB. That's healthy for a ribbon of this type but not enough to drive a low-gain recorder without help. The period review was candid about it: no preamp, and you'd better be within a couple of feet of a loud source. Pair it with professional-grade gear, though, and it holds its own. The slim, neutral-colored body was a deliberate choice for television work. Shure's materials note it's unobtrusive on camera and less intimidating to amateur performers than a big chrome-and-grille studio mic.
The grille is a fine mesh designed to cut wind and blast noise, and the whole thing is compact enough to mount almost anywhere. It ships with a plush-lined box, cable, and cover.
Tape Recording (June 1954, p.36) covered the 300 as a new product at $135.00 complete, and . That's a strong endorsement from a period that didn't hand them out freely.
By the early 1970s the 300 had moved into the used market. A classified listing in DB Magazine (February 1973, p.37) offered a Shure model 300 ribbon mic at $60, less than half its original price, sitting alongside a batch of Electro-Voice dynamics. Newer condensers and dynamics had superseded it in the studio, and collectors and home recordists wanted the ribbon sound without the modern ribbon price.
For anyone considering one today, the appeal is straightforward. It's a genuine ribbon with a genuinely flat top end, three impedance options that make it usable with almost anything, and a documented period review confirming it performed to spec. The −59 dB output means you'll want a decent preamp, and ribbon mics of this era demand careful handling — the ribbon is the fragile heart of the thing. But a 300 in working order is a piece of broadcast history you can actually put in front of a source and use.
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