Introducing OMEC Digital (1975)

In 1975, Orange launched the pioneering OMEC Digital, the first digitally programmable amplifier, built with early logic chips and big ambition.

Peter Hamilton, OMEC Digital Designer, explains the world’s first digitally programmable amplifier: “I designed the OMEC amp in 1974/75. Before that, I’d been a student fixing amps part-time in the basement of the Orange Shop, and then joined full-time as my first job. The brief was simple but bold: ‘design a computerised amp.’ Of course, in those days, computers could cost upwards of a million pounds and needed their own rooms, so some compromises were inevitable.”

A Digital Concept with Analogue Roots

Microprocessors were just starting to appear, but they needed a lot of support chips to function. More compact, single-chip microcontrollers existed for calculators, but they were mask-programmed, meaning tooling was prohibitively expensive unless you were making hundreds of thousands.

The only sensible route was to use SSI and MSI (small- and medium-scale integration) logic chips. The choice came down to TTL — power-hungry but proven and easy to source — or a new RCA technology called COS-MOS, which was more efficient but prone to static damage.

COS-MOS felt too risky at the time, though it would later evolve into CMOS, the low-power microcontrollers used in just about everything today. In that sense, the OMEC Digital was really a digitally controlled analogue amp. Real digital signal processing was still 20 years away.

Ahead of Its Time

The left-hand side of the OMEC circuit board handled the digital logic, storing settings for volume, bass, mid, treble, reverb, compression, and distortion. Four channels of data could be saved and recalled via either the front panel or a footswitch. Those settings were sent to the audio circuitry on the right-hand side of the board via analogue switches.
But there was a snag. The TTL logic drew so much power that the memory alone consumed nearly an Amp at 5 Volts. If the amp lost power, all the stored settings were erased. A backup battery was added, but even that only kept things alive for about half an hour.

In the end, the OMEC Digital was a brilliant idea slightly ahead of its time. It was innovative but lacked the familiar knobs and features players were used to. A few months later, microprocessors like the Z80 and 6502 arrived and kickstarted the personal computer revolution. The rest, as they say, is history.