OPINION

My opinion is that anyone who can put 'ENTER THE WORLD OF PSYCHOACOUSTIC ENHANCEMENT' in bold letters on their boxes must be taking the piss.

We've had lots of enquiries about aural exciters - what are they, what do they do, and are they worth the money, being the most common - so we've taken the Making Music junior hacksaw to the rejigged Aural Exciter Type C, the budget model in the Aphex range in an effort to answer some of your questions.

Most importantly, what do they do? Adding Aural Exciter to your demos/records/PA/TV/breakfast cereal, Aphex claim, will make it sound brighter and clearer, and will enhance the stereo image.

To get an idea of this, try listening to a cassette with Dolby; what happens when you switch the Dolby off is roughly what happens when you switch the Exciter on. They recommend it should be used to improve poor quality tape copies, clean up dodgy PAs, and generally add zing to your sounds. Man.

On the question of what they are, Aphex say this: "the enhancement signal involves frequency dependent phase shift and amplitude dependent harmonic generation."

Phew. The first part of that sentence could roughly be translated as 'we add a v.v. short delay, and an imperceptible chorus, which makes it all sound bigger, but not louder'. The second bit is a tad more complicated: your 'phase shifted' signal is next bunged into a harmonics generator which er... generates harmonics. These have the effect of making the peaks in the harmonic spectrum (usually made by individual instruments) sound warmer, and fuller. Which makes each instrument stand out in the mix, and thus helps the stereo spread. OK? So much for the technical business.

Using the Aural Exciter is easy: it should be the last link in your noise chain before the power amp or recording deck. Connect your output, be it tape machine or mixing desk, into either the phono or jack inputs in the back of the Exciter, then connect the outputs into your hi-fi, power amp, or recording machine. Adjust the Drive controls on each of the independent channels until the LEDs occasionally peak red.

Now you can fiddle with the other two controls. Mix determines the level of the Excited signal, while Tune is a tone control that allows you to excite certain tonal areas more than others. With the Tune knob fully clockwise, the very top end is emphasised (cf Dolby removal); with it central, the middle is brought out; with Tune fully anti-clockwise, the Exciter gets ferociously middley (cf a small transistor radio).

I found the best way of setting up was to switch the Exciter in (using the In/Out switch in the centre of the front panel) with the Mix at minimum, then gradually to increase the level until the effect became audible. Constant In/Out checking helps determine just how useful the Exciter is being.

DECISION

Much myth and mystery used to surround the idea of "psychoacoustic enhancement" even down to suggestions that it could hypnotise you into liking music you'd normally despise. The excellent manual included with the Exciter rejects the idea of subliminal messages, but isn't beyond a bit of sly gobbledygook when things get a bit technical.

I used the Aphex in a number of locations. Connected to a Revox for boosting backing tapes on stage, it performed adequately - the quality of the PA being a more important determining factor, we felt. In an ordinary hi-fi, it did make an obvious difference, with older cassette recordings seeming brighter and clearer. It worked better on funk and other music with holes; dense rock tended to suffer from the change in emphasis on the instruments, particularly the voice.

But it was on demo tapes, and other shitty recordings (what, bootlegs?) that the Exciter became really useful - the worse the tape, the more helpful it became. A grubby Portastudio tape would, if not come alive, at least twitch on the mortuary slab - the vocals, and other mid-range noises were usefully all spruced up. It does boost tape hiss, but the manual gives useful advice on how to get round this (try recording with the effect).

The Aural Exciter is like monosodium glutamate: put a bit on, and it wakes your taste buds up, and makes you hungry for more - useful, eh? Put too much on, and you'll feel sick, you'll get the shakes, and you'll never want to taste surf food again. If you record lots, use it wisely, and it'll be worth the money - otherwise it's an expensive way of feeding your ears.