REVIEWS From Studio Sound



When pro-audio companies start to use a hi-fi vocabulary to describe their equipment it's usually time to tune out. DAVE FOISTER discovers the exception to the rule-the American Avalon company and their AD2055 EQ

AVALON IS NOT YET a familiar name in the UK at least, not when written on a piece of audio equipment. The US company is beginning to get noticed though, initially through interest in its compressor, which is now being followed up with an equaliser, the AD2055.

Audiophile aspirations are becoming more openly expressed in the pro- audio world, a far cry from the days when it was automatically assumed that professional equipment was superior to the consumer's playback system. The Avalon's chief selling-point is the sheer audio quality of its circuit designs, described in the literature in the same kind of terms as those used by the more esoteric hi-fi manufacturers. A glance through the top-panel grille confirms that this is an all-discrete design, with packed motherboards bristling with piggy-back modules, each encrusted with transistors. The smaller boards are mostly identical and are clearly a standard amplifier building block on which the whole design depends. This component density is in stark contrast to much modern equipment, which often contains a few lonely chips in a sea of green PCB. The entire equaliser operates in pure Class-A, which explains the number of heat sinks visible inside and the large one on the rear. This is not a piece of kit to put in a rack immediately below your DAT machine I've seen cooler valve equipment. Its also quite heavy, despite having an external power supply delivering 80V down a heavy-duty cable.

DC coupling is used throughout, including the output- line drivers, and specially selected components include Avalon-badged capacitors and sealed silver-plated relays for switching. The result of all this attention to detail is a claimed frequency response from 1Hz 600kHz (sic) within -3dB, an unweighted 20kHz-bandwidth noise figure of -92dB with the EQ in and a headroom of +30dBu. The match between the bypassed response and that with the EQ in, but flat is quoted as within 0.2dB from 10Hz 62kHz.

The styling is classically American (where else could it come from?) with a plain silver-aluminium, front-panel complemented by machined aluminium knobs. All is reassuringly solid and chunky, and the control labels are printed in a subtle but clear charcoal grey with a fineness that looks like engraving. All the switches are illuminated, and twin power indicators suggest that the two channels have independently regulated supplies.

THE 2055 is a twin-channel, 4-band parametric EQ; although strictly only the mid bands are truly parametric. Bass and treble ends have switch-selectable frequencies and can be switched between peak and shelf operation, and the range on offer makes them uncommonly versatile. The LF turnover point can go as low as 25Hz and the HF as high as 25kHz, and although the slope characteristics are not specified they are gentle enough to make the effects of these extreme settings very audible and useful. At the same time the HF setting can come down to 1.5kHz and the LF up to 450Hz, making them both capable of mid-range duties. The range of gain adjustment is also large, with *20dB for the highs and 24dB for the lows.

The two mid-range bands both have a 7- octave range, achieved in both cases with a X10 switch, and, consequently, have a huge overlap. Between them they cover 35Hz 20kHz, stretching the definition of mid somewhat, but the x10 function keeps them manageable. Up to 16dB of boost and cut is provided on each, together with an infinitely variable bandwidth control giving Qs from 0.3 to 3 not the tightest notch you'll find, but narrow enough for most things, bar tuning out unwanted tones. Matching between channels on all bands seems very precise, allowing reliable stereo use even though this is strictly a 2-channel device with no stereo-friendly features at all.

It's not often I come across a piece of equipment that makes me as dissatisfied with what I've already got as the AD2055 did. However good the figures, EQ stands or falls on its ability to bring the best out of any musical signal, to work with it with precise control, and to do it without introducing any unpleasant by- products of its own, and not many equalisers can truly claim to satisfy all these requirements. The AD2055 is, as can be seen, highly controllable, offering several ways of skinning most cats. The quality of its signal path puts many top-flight pieces of equipment to shame, passing everything transparently and contributing nothing of its own except the EQ itself, as smooth and musical as any I've heard. Whatever I tried to do with it, from vocal EQ to correcting double-bass bug problems to overall mix sweetening, it seemed that exactly what I wanted was just a few knob turns away and sounding better even than I had imagined. This is without doubt a very fine equaliser indeed, with the little bit of magic that comes, it seems, when designers really apply themselves to producing quality at all costs with the best engineering. A special mastering version is due shortly, which I await with eagerness.

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