Postwar fidelity goes portable

In San Francisco, Harry McCune Sr. founded McCune Sound Service in 1932 and rented systems to big bands through the 1930s and 1940s. In 1965 the company began supplying road systems for touring acts, starting with Herb Alpert & the Tijuana Brass.

The war itself rebuilt the industry that postwar live sound would draw on. In January 1942 the US War Production Board converted peacetime factories to military work, and Shure, Western Electric, Electro-Voice, Universal and other American transducer makers retooled to build microphones and headphones for the armed forces. Shure grew from 100 to 1,000 employees between 1941 and 1943, ran its Unidyne lines up to 24 hours a day, and built throat and oxygen-mask microphones for cockpits estimated at 115 dBA and above. When the war ended, S.N. Shure kept military quality specifications for peacetime products, a decision the company's historian ties to the reliability later expected of stage microphones. Electro-Voice's T-45 lip microphone of 1944 attacked the same problem as a design: ports on both sides of the diaphragm let surrounding noise cancel while the close voice came through. Wartime materials work also reached the loudspeaker: James B. Lansing's D130JBLD130 loudspeaker1947The JBL D130, designed by James B. Lansing, is a 15-inch wide-range driver with a 4-inch flat-wire voice coil, Alnico magnet and a 4-inch aluminium dome in place of a dust cap. Leo Fender adopted it for Fender amplifiers in the 1950s.Open profile → woofer used the new Alnico V magnet material developed during the war, and the D130 quickly found favour with cinema and sound-reinforcement users.

JBL D130 loudspeaker© FOH magazine; photographer not credited · Rights retained by the rights holder; reproduced for historical commentary

After the war, cinema components became the live-sound toolkit. Altec Lansing’s Voice of the TheatreAltec LansingA-series Voice of the Theatre1945 series; A7 in 1954Two-way horn-loaded systems combining cinema efficiency with standardized components.Open profile → family, including the A7Altec LansingVoice of the Theatre A71950sThe A7 was Altec Lansing's compact Voice of the Theatre: a folded bass horn with a [[altec-515|515]] 15-inch woofer and a multicellular horn driven by an [[altec-288|288]] compression driver. It scaled the original Voice of the Theatre cabinets down for smaller rooms, and its high sensitivity suited the low-power valve amplifiers of the time.Open profile →, A4Altec LansingVoice of the Theatre A41945The A4 Voice of the Theatre, co-designed by James B. Lansing and John Hilliard and introduced in 1945, paired a horn-loaded bass cabinet with two 15-inch [[altec-515|515]] woofers and a multicellular horn driven by the [[altec-288|288]] compression driver.Open profile → and A2Altec LansingVoice of the Theatre A21945The A2 was one of the original Voice of the Theatre systems Altec Lansing launched in 1945, developed by James B. Lansing and John Hilliard to succeed the [[shearer-horn|Shearer Horn]]. Altec literature describes it as using a Y-throat with two compression drivers and an extra bass cabinet compared with the [[altec-a4|A4]], for the largest rooms.Open profile →, packaged the 288 compression driverAltec Lansing288 compression driver1940sThe Altec 288 is a large-format compression driver with an aluminium diaphragm, developed for the Voice of the Theatre systems. Early versions used Alnico motors with circumferential phase plugs; later ones moved to ceramic magnets.Open profile → and 515 wooferAltec Lansing515 low-frequency driver1945; 515B 1966The Altec 515 is a 15-inch woofer with a 3-inch edge-wound voice coil and Alnico V magnet, designed for large bass horns in the Voice of the Theatre systems. The 515B was catalogued from 20 Hz to 1,000 Hz.Open profile → into standard enclosures. Halls, clubs and later rock tours could buy them off the shelf. The coaxial Altec 604Altec Lansing604 Duplex1944The Altec 604 Duplex was a 15-inch coaxial loudspeaker whose compression-driver tweeter fired through the woofer's pole piece into a small multicellular horn. It followed the 1943 model 601 but used an Alnico V permanent magnet instead of a field coil.Open profile → put both drivers on one axis for smaller rooms.

Altec Lansing A-series Voice of the Theatre© Altec Lansing Technology, courtesy Paul Barello · © Altec Lansing Technology; used for identification and historical commentaryAltec Lansing Voice of the Theatre A7© FOH magazine; photographer not credited · Rights retained by the rights holder; reproduced for historical commentaryAltec Lansing Voice of the Theatre A4© FOH magazine; photographer not credited · Rights retained by the rights holder; reproduced for historical commentaryAltec Lansing Voice of the Theatre A2© Altec Lansing · © Altec LansingAltec Lansing 288 compression driver© Altec Lansing Corporation · © Altec Lansing; used for identification and historical commentaryAltec Lansing 515 low-frequency driverJacques from Cape Town, South Africa · CC BY 2.0Altec Lansing 604 DuplexAuthor unknown · CC0

James B. Lansing’s new company, JBL, pursued the same goals with more efficient parts: the D130JBLD130 loudspeaker1947The JBL D130, designed by James B. Lansing, is a 15-inch wide-range driver with a 4-inch flat-wire voice coil, Alnico magnet and a 4-inch aluminium dome in place of a dust cap. Leo Fender adopted it for Fender amplifiers in the 1950s.Open profile → woofer and the 375 high-frequency driver. Later rock engineers loaded exactly these parts into bass horns and flying clusters.

JBL D130 loudspeaker© FOH magazine; photographer not credited · Rights retained by the rights holder; reproduced for historical commentary

Microphones were redesigned to fight feedback. Shure’s 55SShure55S Unidyne1951The Shure 55S 'Small Unidyne' was a smaller version of the 1939 [[shure-55-unidyne|Model 55 Unidyne]], using the same Uniphase network for single-element cardioid pickup in a smaller case with a tilting head.Open profile →, the Unidyne III / 545ShureUnidyne III / Model 5451960A compact unidirectional microphone lineage that helped define the modern stage vocal mic.Open profile → and the Unisphere 565Shure565 Unisphere1960sThe Shure 565 Unisphere I is a dual-impedance cardioid dynamic microphone with a spherical wire-mesh grille containing a wind and pop filter, intended for theatre stage systems, recording and large PA such as conventions and stadiums. It is nicknamed the 'Woodstock microphone'.Open profile → used cardioid patterns to reject sound from the PA. Electro-Voice’s 664Electro-Voice664 dynamic microphone1954The Electro-Voice 664 was the first EV microphone to use the Variable-D design, in which multiple rear sound entrances keep the cardioid pattern consistent with frequency and reduce proximity effect. Its die-cast zinc body earned it the nickname 'Buchanan Hammer'.Open profile →, AKG’s D12 and Sennheiser’s MD 421SennheiserMD 421 microphone1960The Sennheiser MD 421, launched at the 1960 Hannover Fair, paired a large dynamic capsule with a closed housing that kept its directional pattern however it was held, plus a hum-compensating coil and a multi-position bass roll-off.Open profile → spread the idea across Europe and the US. Balanced lines carried these signals further with less noise, into RCA’s transistorised BN-6A portable remote amplifier (1958) and levelling amplifiers such as the Gates Sta-LevelGatesSta-Level compressor1956The Gates Sta-Level (M5167), documented in an instruction manual dated 30 April 1956, used a 6386 variable-mu valve to give roughly 3.3:1 compression with low distortion. It became a fixture of AM radio studio chains.Open profile →.

Shure 55S UnidyneEthan Long · CC BY-SA 2.0Shure Unidyne III / Model 545Charles E. Seeler (Shure Brothers) · Public domain (US patent)Shure 565 UnisphereJud McCranie · CC BY-SA 4.0Electro-Voice 664 dynamic microphonedoryfour · CC BY-SA 2.0Sennheiser MD 421 microphoneKreuzschnabel · CC BY-SA 3.0Gates Sta-Level compressoreyeliam · CC BY 4.0

Power rose with the audience. Valve amplifiers like the McIntosh MC30 and MC60 gave way at the end of the 1960s to the solid-state Crown DC-300CrownDC-300 amplifier1967The Crown DC300, designed by Gerald Stanley, was introduced in 1967 as a reliable solid-state amplifier rated at 150 watts per channel into 8 ohms, when 50–100 watt valve amplifiers were considered large. It sold for about $685.Open profile →, and British groups used dedicated vocal systems such as WEM’s PAWatkins Electric MusicWEM vocal PALate 1950s–1960sBritish column systems and mixers designed to carry vocals over increasingly loud guitar amplifiers.Open profile →. The gear was still too small for stadium rock, but the parts and the craft of the next era were in place.

Crown DC-300 amplifierBinksternet · CC BY-SA 3.0Watkins Electric Music WEM vocal PA21st CENTURY GREENSTUFF · CC BY 3.0

After the war, amplifier designs like the 1947 WilliamsonD. T. N. WilliamsonWilliamson amplifier1947D. T. N. Williamson published 'Design for a High-Quality Amplifier' in Wireless World in April and May 1947: a four-stage push-pull amplifier with triode-connected KT66 outputs, deep negative feedback and a wide-band output transformer, giving about 15 watts at very low distortion. It was reprinted as a booklet and copied widely through the 1950s.Open profile → and the 1945 Leak Point One showed how far low-distortion valve gain had come. Both were designed for domestic listening; their low-distortion valve circuits informed professional amplifiers too.

D. T. N. Williamson Williamson amplifierRetired electrician · Public domain