Almost 20 years ago, I read a review in Sound On Sound of a truly unique instrument. That instrument was the Metasonix S1000 Wretch Machine, a synthesizer that uses tubes (also called valves) in every stage of the signal path. I never got a chance to acquire a Wretch Machine, which was only ever produced in small numbers. But I simply had to get my hands on tube‑based technology and try it for myself.
First I got a small, affordable tube preamp. At lower volume levels, I couldn’t hear much of a difference. But when I increased the input volume to near the maximum and ran a Korg Monotribe through it, it compressed and distorted the signal like nothing I’d ever heard before. The monophonic sequence and the drum pattern were squeezed into a molten mass where each took turns struggling to the surface. The Monotribe sounded livid. I’d used many distortion pedals, from cheapies to classics, but this was new.
Eventually I bought a Eurorack modular case that was designed to satisfy the larger power demands of tube modules, which I began to collect. After five years with this system, the sound of tubes still fascinate me. A tube ‘filter’ is a long way from a standard low‑ or band‑pass filter: it’s better to think of it as a processor and just let it affect the sound the way it wants. Rather than precision, tubes deliver unpredictability, adding trills, squawks, squeals and growls.
Once, when I contacted the manufacturer of a tube distortion and told him I wasn’t getting the expected results, he replied: “Try sending an oscillator to the CV input, and a CV signal to the oscillator input.” I wasn’t expecting that to work, but somehow it did. (I’d be shocked to hear this advice for a solid‑state or digital module.) But it reminded me that the strong point of using tubes for synthesis is the mystery and the unpredictability of the circuits and their operation. It’s the Sun Ra school of synth programming: it doesn’t matter if you don’t know what the knob does. Just turn it until things sound interesting.
The depth and variety found in tube distortion is an endless well... You will find an almost inexhaustible source of strangeness.
And the depth and variety found in tube distortion is an endless well. You probably won’t be able to duplicate some of the sounds you find the next day, or reliably dial in a classic Hendrix tone on demand. You will find an almost inexhaustible source of strangeness.
Of course, you also have to make compromises. Tubes heat up, requiring air circulation. Tube oscillators drift out of tune easily, have difficulty tracking more than an octave, and generally fail to deliver a lot of stock synth sounds that most players need, such as FM pianos or realistic drums. If I want to create traditional tonal music, I tend to sequence an analogue or digital oscillator that I feed through tube processors to add character.
Near the end of Paul Nagle’s Wretch Machine review, he concluded: “I’ve been able to dust off a fresh batch of adjectives for this review, but more importantly I’ve been challenged to think again about what constitutes synthesis and electronic music.” I agree, but the adjectives aren’t really the point. Forget why I love tubes: listen to them for yourself and decide how you feel about them.