DIY for the guitar & bass player with Kent Armstrong's add-on active kit. IT warms up the soldering iron

Apart from making some of the world's finest pickups and supplying almost every British guitar maker, Kent Armstrong has been thinking hard about other influences on guitar and bass sounds. Teaming up with electronics whiz Jerry Evans, the two have designed a build-it-yourself 'active' kit which we've recently been trying.

The ATC 2 kit comes in a plastic bag, complete with a fair-sized ream of printed instructions which tell you not only how to assemble the components, but also the various optional ways of wiring it inside your instrument. The idea behind the Armstrong kit is simple yet enormously effective once you've got it installed. Suitable for both basses and guitars, it includes four potentiometers which you can use either to give your instrument battery powered master level, bass and treble controls (most suited to single and triple pickupped types), or (with a twin pickupped instrument) to have master volume and a pan pot arrangement plus your tones, or one volume control per pickup.

Assembling the various components is either going to be a piece of cake or a bit difficult, depending on how neat you are with a soldering iron and how much redeye you knocked back the previous night! Probably the most nerve-racking job involves soldering wires to the circuit board — a delicate task requiring a fairly low wattage iron and a bit of care. If you reckon you're up to this, then assembling the rest of the kit will be simple. If you've any doubts about your skill, then rereading our article on soldering in Issue 5 (copies of which are still available) should soon set you right.

Once you've chosen which configuration you want, assembled the components and fitted them inside your guitar or bass, what sort of effect do they have? To make it possible to test the ATC 2, we didn't strip apart and re-wire half a dozen guitars, but used it in a box through which we plugged as wide a range of instruments as we could get our hands on. Basses went first, starting with a cheap and fairly average-sounding Korean type. After that came a Tokai Jazz, then a Westone Concord.

In each case the circuit had two very noticeable effects. The first of these was the obvious (and very effective) way in which the tone controls could be used to boost and cut treble and bass tones. This isn't one of those active circuits which goes over the top and provides the user with more sounds they can't use than those they can. In fact it's really quite subtle, but all the better for that. In figures, you get 15dB cut or boost @ 100Hz on the bass side and ± 15dB @ 2.8kHz treble. The levels are obviously right and the frequencies sensibly chosen.

We said earlier that the circuit seemed to have two effects, and it was the second which was really remarkable. With all three controls on full (ie bass, treble and master volume) the ATC seems able to work the miracle of turning the sound of a cheap bass into that of an expensive one. The effect it has is to put a huge shovelful of coal on the fire — fattening and enriching the sound, dragging previously absent harmonics out of the wood and making even our cheapest and nastiest bass sound like three times the instrument it was before.

Surprised by this revelation, we quickly swapped over to a really foul and tatty Strat copy. It happened again. Once more, the tone controls worked to boost the top and bottom frequencies by very respectable degrees, but it was the effect when all three were full on which really transformed the guitar.

As we went up the quality scale, this almost magical effect became, as you would expect, less necessary, although by the time we reached a Gibson and a Strat another quality appeared. We all know how unpopular active guitars tend to be — many players reckon that active circuitry destroys the natural sound of their pickups. Well, the ATC 2 doesn't. In fact, with the tones set centrally, the guitar (or bass for that matter) sounds just as it normally does. All you get is extra sounds as and when you want them. This give any guitar considerable additional versatility with no loss of its own character.

CONCLUSION

Providing you're not completely cack-handed, the ATC 2 isn't difficult to either assemble or instal. In case you're worried about having to keep your battery buried beneath the scratchplate, you shouldn't be. You could, of course, cut a battery compartment into the back of your guitar (you could try DIY brain surgery as well!), but on the whole we don't feel that having to replace the battery every six months or so the hard way is that much of a chore.

Apart from the way it boosts available tones and yet doesn't destroy the sounds you've already got, what really appealed to us about this kit was the way in which it can do exactly the job which you might otherwise have to spend well over £100 on a new set of pickups to do. Forking out that sort of money on a £100 guitar has never seemed sensible to us, and looks even less so since we've tried the ATC 2.

And now the really good news. We're so knocked out by this kit that we've used ITs buying power to arrange a unique price reduction Special Offer exclusively for IN TUNE readers. You'll find details of this elsewhere inside this issue! Meanwhile, you can get more info on the Armstrong ATC 2 as well as Kent Armstrong's Rainbow pickups and rewind service direct from him at Kent Armstrong, (Contact Details).

RRP £40.25 inc. VAT