By way of a coda to May's echo unit supplement we should mention Aria's new AD-05, which combines the presentation of a studio digital unit with the simplicity and relative inexpensiveness of analogue design.

The AD-05 comes in a one unit high, nineteen inch rack mounting format. The box itself only occupies about two thirds of this width, and the projecting ends of the front panel are rather thin and flexible, but since the unit is very light this shouldn't be a problem. Unlike a professional studio model, connection sockets are on the front panel only.

There are two quarter inch jack input sockets, Mic at minus 46dB and Inst at minus 26dB. Next to these is a Peak LED together with an input attenuation control, calibrated from 0 to 10, which make it possible to set the optimum input volume to avoid distortion.

The other three main controls, which like the level control use knurled grey knobs with smart white caps, are the conventional Balance, Feedback and Delay Time. Balance is labelled from Dry (anticlockwise) to Delay (clockwise) but unlike Level and Feedback isn't also calibrated from 0 to 10. Feedback controls the number of repeats produced, and ranges from one to runaway — various motorbike sounds and howling feedback effects can be produced at high settings.

It's also interesting to alter the Delay Time control during the course of an echo. This momentarily changes the pitch of the sounds being played, and since the circuit contains voltage controlled elements it wouldn't be impossible to add an LFO to modulate the Delay Time and produce vibrato.

The maximum delay is about 300mS, and the minimum delay about 25mS. This allows variation from a reasonable repeat echo effect, with slap-back if only one repeat is selected, to a harsh metallic reverb if short delay times and high feedback are used.

Next to the rotary controls are two more jack sockets, for footswitch (to switch the echo effect on and off, but not supplied with the unit) and for Output. This is a simple mix output and has a vertical slider switch to select levels of minus 20dB or minus 40dB.

The final front panel features are a small metal Power toggle switch and an associated green LED. The rear panel carries a fuse holder, and the underside of the casing has four rubber feet in case the unit needs to be used in a free-standing application. In this case it would have been useful to be able to unscrew and remove the projecting ends of the rack mounting plate.

Internal construction is reasonable, with a separate power supply, control pots wired direct to the PCB, insulating tape to isolate the circuitry from the casing, and neatly-designed aluminium plate construction. The casing finish is in stippled matt black, and the whole unit though lightweight is fairly good looking, with the white knob caps contrasting with the semi-gloss metallic grey front panel.

Theoretically the AD-05 is only a starter's echo, with the loss of treble and metallic sound quality unavoidable in analogue designs of this single delay line kind. However, it's interesting to see this kind of unit turning up in a rack-mounting format, as the home musician is inevitably becoming more space-oriented and racked equipment, although desirable, is generally more expensive than is the AD-05.

The Aria AD-05 Analog Delay is available via Gigsville, (Contact Details), at a price of £119.42 including VAT.