RAISING THE TONE …
Jamie Dickson and Nick Guppy look back on how Roland’s JC-120 became the rare transistor amp that everyone loved
In recent years, advances in digital modelling amps have, at last, offered a variety of non-valve amps that most of us would be happy to use in one context or another. But prior to the digital revolution, the much-maligned analogue transistor amp was generally regarded as a poor relation to classic valve amps. There were, however, some honourable exceptions…
BB King used Lab Series amps at one point, as did Allan Holdsworth, and British-made Award Session amps were used by Clapton on his 1986 August album and remain well respected. But the undisputed king of solid-state amps is Roland’s beefy 120-watt, chorus-equipped JC-120 – which became standard kit in studios around the world and has appeared on scores of hit records – primarily for its pristine-yet-warm clean tones.
With a special-design, limited-edition Anniversary model hitting the shops, it seemed a good moment to ask how Roland found a well of tone in transistor amps where others had come up dry.And for that, I turned to our resident amp expert Nick Guppy, who says the first key element in the amp’s success was its in-built stereo chorus effect: common enough now but a rarity when the JC-120 came out.
“Nearly five decades ago, time-based modulation effects were the preserve of expensive studio equipment, so to bring out a guitar amplifier with built-in chorus and vibrato was a big deal,”Nick says.“In an era when transistor amps were prone to failure and many guitarists wanted high-gain boutique valve products, Roland’s JC-120 went in the opposite direction, delivering the cleanest of clean sounds with headroom to spare and proving transistors actually could be reliable.”
Nick adds that chorus wasn’t the only effect Roland built into its burly new combo – but it was the feature that ‘broke’ the JC-120 on the world stage.
“The JC-120’s built-in effects included footswitchable distortion and a spring reverb on Channel 2, plus a pitch‐shifting vibrato. But it was the warm analogue chorus innovation, which was generated by the nowobsolete MN3002 dual BBD chip, that catapulted the JC-120 into the stadium league. It has been used by artists all over the world for genres as diverse as African roots, reggae and metal, from Pat Metheny to The Police and Metallica. Today, every pedal builder has at least one chorus product in its line-up, but in 1975 there wasn’t anything like it – and it was another year before Roland repackaged the JC-120’s chorus/vibrato circuit into the equally legendary Boss CE-1.
“Real chorusing is a stereo effect, with the pitch of one channel modulated cyclically up
