“The Uni-Vibe was an excellent alternative to a Leslie and became a mainstay for Jimi Hendrix”: Everything you need to know about modulation, from Leslie emulators and chorus pedals to bucket-brigade chips and phasers

In our recent feature on tremolo, we described how a valve can be configured to create a low-frequency oscillator (LFO) that can modulate amplitude.

You can’t actually hear the oscillator itself, merely the effect it has, and that effect isn’t restricted to tremolo. In addition to amplitude, an LFO can be used to modulate pitch, frequency response, phase and delay – and that leads us onto vibrato, chorus, flangers and phasers.

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Huw started out in recording studios, working as a sound engineer and producer for David Bowie, Primal Scream, Ian Dury, Fad Gadget, My Bloody Valentine, Cardinal Black and many others. His book, Recording Guitar & Bass, was published in 2002 and a freelance career in journalism soon followed. He has written reviews, interviews, workshop and technical articles for Guitarist, Guitar Magazine, Guitar Player, Acoustic Magazine, Guitar Buyer and Music Tech. He has also contributed to several books, including The Tube Amp Book by Aspen Pittman. Huw builds and maintains guitars and amplifiers for clients, and specializes in vintage restoration. He provides consultancy services for equipment manufacturers and can, occasionally, be lured back into the studio.