Last month's news that Aphex were to replace the Type B with the Type C certainly generated plenty of excitement. Paul Gilby took delivery of one of the first production models to arrive in the country and checked out the latest psychoacoustic phenomenon.

It's amazing really to think that the price of the Aphex Aural Exciter has been steadily falling over the past two years or so and the product is still around in a form very close to the original. Unlike many products, the lifespan of the Exciter has been a long one, it's never been a case of dropping the price and superseding it with an entirely new model that goes off in some completely new direction, full of memories and MIDI with little else in common with the original. Like Quad amplifiers, the Exciter design just goes on and on. Aphex have never made their equipment obsolete, rather they have developed the idea of the Aural Exciter very carefully.

It has been this long development over a ten year period that has seen Aphex produce products that are firmly established amongst the professional studios of the world. Originally, the Exciter was the mysterious box that you could only hire and then when a model did become available, it wasn't cheap. Over the past year or so the Exciter has slowly but surely broadened its appeal as price reductions have brought it within reach of the semi-pro and the 8 and 16 track middle studio market.

The years of carefully controlled marketing and patent protection have now paid off, for everyone, as increased sales of the Aural Exciter have prompted the manufacture of a custom 'chip' that has resulted in higher production capacity. The new Type C moves yet again towards a broader market with the most affordable price to date - only £299. It's this sort of marketing philosophy that makes you think that Aphex are looking towards the position that Dolby, whose noise reduction circuit is found in almost everything, currently occupy. They certainly seem to be following the same route, for the Exciter has many applications and could easily be used to enhance practically anything that produces audio: TV, video recorders, cheap cassette players, car phones and even in car Hi-Fi. Now there's an untapped market...

The immediate and most obvious difference between the Type B and C is that the whole front facia has been restyled and uses a new recessed aluminium extrusion. However, the traditional metallic blue colour has been retained, giving the unit an unmistakable Aphex feel. The same controls are there as before: Drive, Tune and Mix, and if required you can remove the rack-mounting ears. Any real differences between the Type B and C appear on the back panel where the new Type C sports phono sockets wired in parallel to the standard jacks, which should help broaden its appeal to Hi-Fi buffs and even DJ's.

ELECTRICAL

The main change on the electrical side of things is that the Type C, in keeping with its reduced cost and broader appeal, comes wired as a -10dB input/ouput level unit instead of the more usual 0dB level for studio operation. However, we're told by the UK importers that a modification for conversion to 0dB is available and should be specified if required. The lower operational level isn't a problem though, for as everyone knows many of the mixers and tape machines today operate at the -10dB level.

Before actually describing the effect an Exciter has on sound, its worth talking about the sonic differences that exist between the Type B and C.

To be frank with you, there aren't any that are worth talking about. A practical listening test in the studio with both units side by side, revealed little difference in the sound quality. If there was a discernible difference it was in the range of the Mix control, which seemed to offer more of the processed effect than before.

APPLICATIONS

Exciters have really started to take off in this country and much has been written in the last few months in various music magazines to explain their use.

Briefly, the application of Exciters falls into two categories: sound enhancement and sound restoration.

It's use for enhancement includes lifting sounds out of a mix, such as the cymbals of a dull-sounding drum kit which has been recorded too quietly or for improving the stereo image of a sound. This is a true example of the psychoacoustic phenomenon, as the addition of upper end harmonics is precisely the sort of aural information that our ears use to perceive the direction of a sound. Similarly, a touch of Exciter on a reverb helps to give that little extra sense of perspective. By tuning the Exciter to the right frequency range for the sound you wish to treat, you can restore the sparkle and clarity to almost anything.

Applications as a sound restoration device are numerous and it's in the field of tape copying that some pretty astounding results can be obtained from even the worst sounding originals. The ability to restore the 'lost' upper harmonics of any sound makes the Aphex absolutely indispensable for treating the output from the current generation of sampling devices, whose sometimes restrictive bandwidth limitations all but disappear when Excited.

THE SECRET

Technically, the Aural Exciter is essentially a kind of very sophisticated distortion device. Figure 1 shows the basic parts of the circuit. Any signal entering the input is split into two parts, one is sent unmodified to the output and the other through what is known as the sidechain. It's here in the sidechain that all the real work is done.

The Tune control allows you to filter out whichever section of the sound between 1kHz and 5kHz that you want to effect. This is a relatively narrow range but is actually the most important in terms of human hearing as it's this section of the audio bandwidth that our ears are most sensitive to.

After filtering, the signal is processed through the harmonics generator which adds harmonics relative to the strength of the fundamental. Even if the upper harmonics of a sound aren't present in an original it's possible to add artificial ones. This is best described by a quote from the Aphex manual: "You can actually generate a new, musically correct 'synthetic' high frequency end free from the noise of the source tape, with full brightness and clarity". And it's true! What's more, you can do this in stereo or use the two channels individually on different mono sound sources.

All told, the Type C should not be judged simply as a compromised Type B. The original quality has been retained yet the price is lower and additional connection sockets have been fitted. It's definitely going to attract a lot of new interest, as Aural Exciters have always been one of those mysterious effects units that many people don't understand the need for and consequently are never given a very high priority. Maybe the new price will change that now, for after a reverb, echo, compressor and gate an Exciter should come fairly high on the shopping list.

It would seem that with the introduction of the Type C, Aphex are making positive steps towards exciting everyone.

Price £299 including VAT.

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