Shure Model 548 Unidyne IV
A cardioid dynamic built to survive a karate chop, sold at a hundred dollars, and road-tested by The Who.
Overview
Shure's own advertising for the Unidyne IV said the mic was "so rugged that it can withstand a Karate chop," with a reinforced, cushioned cartridge built to take "the full force of a leather-lunged Karate yell." That's marketing copy, not a lab result. It does show who Shure expected to buy the thing. The frequency response spec was 40 to 15,000 Hz, wide-range for a dynamic of the period. The Unidyne IV was positioned as the newest and premier member of the Unidyne family of true cardioid dynamic microphones, with pickup said to be symmetrical about the microphone axis at all frequencies and in all planes.
The 548 is the hand-held version, listed at $100.00. A companion Model 548S added an on-off switch and a swivel connector for stand use and carried a $105.00 list price. Both share the uniform cardioid pattern, dual impedance, and the feedback- and "boom"-resisting behavior Shure claimed for the line. The Cannon-type connector, the professional XLR-style fitting, points at the intended market. Shure also advertised that the mic was exceptionally easy to service in the field. Audio (April 1969, p.58) profiled the 548 in its Equipment Profiles section and noted that the Cannon XL-3-12 connector, along with the impedance-matching transformer wound with two secondaries, made clear this was a professional model rather than a consumer piece.
Contemporary Shure literature tied the mic directly to The Who, naming the Model 565D Unisphere I and the Model 548 Unidyne IV as two of the Shure microphones the band used. That's a promotional association, not an endorsement contract, but it's the kind of placement that sold mics in the late '60s. The 548's durability pitch and the 40 Hz low-end reach made it a natural for loud stage work where a vocalist is fighting a wall of amps.
eBay Listings
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.