HH Audio (formerly HH Electronics) is a British amplifier manufacturer that was founded in 1968 by Mike Harrison near Cambridge, England.^[1] The company moved to Milton, Cambridgeshire, in 1969,^[2] and had built a factory in nearby Bar Hill by 1977.^[3] By 1979, they had achieved success in Europe with a range of instrument amplifiers, and their public address products included mixers, power amplifiers, speaker systems and digital effects units.^[4]

The company entered receivership in 1984,^[5] and the brand passed to Carlsbro.^[6] Mike Harrison continued to design amplifiers as Harrison Information Technology.^[7] By 1989, the HH Electronics brand was owned by the Headstock Group, owners of Laney Amplification.^[1] Headstock revived the brand in 2012, launching a new line of sound reinforcement equipment.^[8]

HH was initially known as a manufacturer of audio amplifiers, and found early success with solid state power amplifier designs.^[9][6] Its first solid state studio-quality amplifiers, such as the TPA50, were used by many recording and broadcasting studios, including Apple Records,^[10] LWT's Intersound Recording Studios^[11] and the BBC (for whom HH built the AM8/12 studio monitor amplifier).^[12][13]

The early 1970s saw HH's first power amplifiers using integrated circuits. The IC-based TPA D range was introduced as a successor to the TPA series, including the TPA25D, TPA50D and TPA100D.^[14][13] For PA applications, the IC100 power amplifier and MA100 mixer amplifier, both delivering up to 100 watts, were available in the UK and Europe by late 1972.^[14][15] The IC100 was also available for musical instrument use in a combination version built into a cabinet with two speakers.^[14] The MA100 offered five input channels with bass and treble EQ, and built-in reverb; the MA100S was a lower-cost version without reverb.^[16] The IC100 introduced the striking electroluminescent panel lighting^[17] used on HH's instrument amplifiers through the late 1970s,^[9] with the company changing to more conventional panel designs in the 1980s.^[18]

HH introduced an electronic piano, the P73, in 1981.^[19] The P73 offered five piano and clavichord voices, and was controlled by a microprocessor. The P73 was used by keyboardist Duncan Mackay.^[20]

HH's final generation of amplifiers, the V series introduced in 1979, were based on MOSFET technology, allowing higher output powers with low distortion, and incorporating more sophisticated cooling and output protection features.^[5] A 1982 US review of the HH V800 described it as a superbly-crafted piece of equipment—utterly reliable and virtually indestructible.^[21]

In late 1983, HH Electronics launched the Tiger microcomputer, the design of which having been acquired from Tangerine Computer Systems, featuring a Zilog Z80 processor equipped with 64 KB of RAM for running the CP/M operating system, a Motorola 6809 processor with 2 KB of RAM for input/output control, and a NEC 7220 video controller with 96 KB of RAM supporting 80-column, 40-column and videotex-style text modes along with an 8-colour 512 x 512 graphics mode. The machine was equipped with a modem for access to Prestel and other online services. As was common with microcomputers of the era, the core functionality was situated in the keyboard unit, with a separate unit combining a 14-inch colour display and dual floppy disk drives. The base system was priced at £2,795.^[22]