JHS DX-5 Pro-Rhythm Mini Synth
Fans of the E&MM Syntom and Synwave (and there are many) may find the idea behind this unit a little familiar! The JHS DX-5 is a percussion synthesiser which can be triggered either by hitting the case with a drum stick or finger (there is an internal transducer) or by being mounted on a drum. A bracket is provided which clamps on to a drum rim, and when the drum is hit, the synthesiser is triggered.
The unit is very compact, being mounted in a matt black diecast case measuring 120 x 60 x 35mm. There are eight knobs, two switches and two jack sockets mounted on this, and the synth is powered by an internal PP3 battery; so there can't be much room left inside for the circuitry!
The main sound source is an oscillator which produces sine waves, with a pitch range from 50Hz to 3.5kHz. The amplitude of the sound is controlled by an envelope shaper with variable decay and fixed attack. In other words, the sound starts immediately the unit is triggered, and then takes between 0.4 and 12 seconds to die away. Here we have the essential elements for synthesising most non-metallic percussion instruments, drums and woodblocks for instance. Anything from bass drum to claves may be imitated, and many other percussive sounds can be generated using just these two controls.
One other factor in drum synthesis is this: when a drum skin is hit, the initial impact of the stick or beater stretches it, and the tone tends to start high and then settle down to a lower pitch as the sound decays. The "sweep" control allows the DX-5 to do this, and the effect can be greatly exaggerated to produce that "pinging" sound which has been done to death on so many disco records.
Another sound source is provided in the form of a noise generator, which can be switched to give white or pink (filtered) noise. The "balance" control mixes the noise and oscillator outputs in any proportion. A little noise may be used to roughen up the sound slightly — drum skins never produce a pure tone — or a bit more gives a snare drum effect. Alternatively, using the noise source by itself, a reasonable attempt may be made at producing cymbal and clap sounds.
For more electronic sounding effects, vibrato may be introduced. A low frequency oscillator with variable rate and depth modulates the main oscillator frequency for a wide range of weird outer space sounds. (Actually, sound doesn't travel in outer space because it's a vacuum, but you know what I mean.) The only controls left to cover are a volume control, which works as volume controls do the world over (maximum output is 500mV p-p); a footswitch socket for turning the whole thing off when you don't want it, if it's mounted on a drum for instance; and the "intensity" control. This adjusts the unit's sensitivity — it is touch sensitive — and ensures that it isn't set off by external sounds, such as the bass player's 300W stack two feet from your right elbow.
The number of controls on the box means that finding somewhere safe to hit it is a bit of a problem, and I would think there's a good chance of breaking something with a misplaced drumstick, hastily lashed out in the middle of a percussive cacophony (drummers are such beasts); also, it's a pity there's no external trigger for operating the unit automatically, from a Synclock for example.
Apart from that, the DX-5 is simple to set up and operate, it produces a vast range of sounds, and it's fun: there's no law against that, contrary to popular rumour, and at £45 including VAT it's a lot cheaper than some other sources of fun I could mention (but won't).
JHS products are sold by John Hornby Skewes & Co Ltd, (Contact Details).
Review by Peter Maydew
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