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Alesis Quadraverb Plus

Multi-fx Processor

Article from Music Technology, April 1991

Possibly the most popular budget multi-fx processor currently available, the Quadraverb has just been upgraded and promoted to the rank of 'Plus'. Nigel Lord investigates.

The recession bites, and many of us are looking for the most cost-effective way of improving our studios. One option is equipment upgrades - Quadraverb owners come on down.

WHAT WOULD YOU expect to be able to buy for 12 quid these days - a box of floppies perhaps? A reel of quarter-inch recording tape or a decent MIDI cable or two maybe (so that you don't have to keep stealing the one off the stereo system which doesn't work properly anyway). In the light of this rather modest prospect, how would you fancy a multi-tap delay/resonator/ring modulator effects unit for the same amount? In case that's not interesting enough in its own right, how about adding auto-panning and tremolo effects to the offer? And (to make it a tad more interesting), suppose we gave it a sampling capability - just to help out when the Synclavier is full. Does that sound like a good 12 quid's worth? Alesis obviously think so.

The catch? Well, if you're one of the thousands of people who own a Quadraverb there isn't one really. Just send a cheque for £12 to Sound Technology pic and they'll send you a shiny new chip for your unit which will provide all the above effects - in addition to those it is already capable of. If you don't own a Quadraverb, things are likely to be a bit more expensive, I'm afraid. But nevertheless, in the Quadraverb Plus, you'll be getting arguably the best specified sub-£500 multi-effects unit on the market - sub-£400. Still interested? Read on...

The policy of upgrading is nothing new of course, but Alesis do seem to be more diligent than most in making the benefits of continued research in their products available to existing customers. Already we've had upgraded versions of the HR16 (via the HR16B) and the DataDisk (now suffixed with an SQ). Now it's the turn of the popular Quadraverb.

The upgrades are listed in a separate manual, which I understand is made available to existing owners who send off for the new chip; those investing in the Quadraverb Plus will find themselves in possession of two manuals amounting to more than 125 pages of user information. Not bad for an effects unit. And it's all well written and very explicit.

Of all the new facilities, I suppose it's sampling which is likely to be the most sought after. Though there is a precedent for including sampling facilities on an effects unit, the Quadraverb Plus takes it on board in a fairly serious way. Though maximum sampling time is limited to 1.55 seconds, you are given a range of editing and looping options which help make this a much more usable tool.

Sample recording is initiated either manually (by pressing Bypass) or automatically (by a signal above the threshold level). Subsequent playback is possible using manual or audio triggers - the former requiring a jab on the EQ button, the latter a signal sufficient to light the -18dB LED on the front panel. MIDI triggering is also possible, and here again, two options exist. In One Shot mode, a note-on message from any key of an external device will trigger the sample which will play for its entire length, regardless of when the key is released. In Gated mode, on the other hand, playback of a sample is linked directly to the note-on/note-off messages of the external device. Press a key and the sample plays, release it and playback stops. Press a different key and the sample plays back at the corresponding pitch. Press two keys and... sorry, this is strictly monophonic sampling, you'll have to find room on the Synclavier after all.

Looping is a straightforward in/out function and as such is somewhat unpredictable in terms of how well it performs. You can adjust the start and end points of complete samples (in ten millisecond steps) - but not of the loop in isolation. The quality of your samples, therefore, depends very much on the nature of the sound itself: there's little you can do to obviate clicks or any of the other unwanted side-effects associated with looping.

Limitations aside, this is still a very usable feature - particularly for percussion samples which are relatively short, do not require looping and can be triggered in the One Shot mode. And don't forget, we're talking 16-bit sampling here: providing you don't move too far from the "base" pitch (when the effects of munchkinisation become noticeable), it is possible to achieve some very high quality results indeed. The only real disappointment as far as I'm concerned is absence of any storage facility. When the power supply is lost, so are the samples, I'm afraid.


BACK IN THE late '70s/early '80s, there wasn't a synthesiser worth its salt which didn't sport a ring modulator amongst its complement of sound manipulating tools. As the mass "digitalisation" of equipment took place, however, this particular form of modulation became less and less common. Today it seems to have all but disappeared from hi-tech instruments - and represents a criminal omission from the synthesist's palette. Full marks, then, to Alesis for acknowledging its potential and including it as an effect among those we are more accustomed to seeing on signal processors.

Essentially, the ring modulator provides us with a means of amplitude modulating two signals such that the resultant output comprises only of sum and difference harmonics. This contrasts with conventional forms of modulation where sum and difference frequencies are heard in addition to the modulated signals themselves. The resultant sound, has, depending on the type of input signal, a ringing, metallic quality, rich in harmonics and very resonant.

On the Quadraverb Plus, the Up and Down output signals produced by the ring modulator are routed to the left and right outputs. These represent versions of the input signal with its harmonic spectrum shifted up and with it shifted down and you can adjust the overall level of each. Don't confuse its effect with that of an exciter which simply adds a little top-end sparkle. This is a very distinctive form of signal processing which needs considerable care in setting up if it isn't to sound clangorous and unusably discordant.

A similar, but more straightforward effect is provided by the Resonators which the Quadraverb Plus now sports. Like the ring modulator, these generate harmonic derivatives of the input signal - but in a much more controlled way. The Plus boasts a total of five Resonators; the fundamental frequency of each may be adjusted in semitone steps from -24 to +36 (in other words, across a five-octave chromatic scale). This takes place in Continuous mode, where it is also possible to adjust the decay time of each resonator on a 0-99 scale.

In the second Resonator mode, MIDI Gate, the frequencies generated can be made to track incoming MIDI notes from an external device. And because resonator frequencies can be adjusted, you can therefore program the Quadraverb to generate up to five-note chords from any type of input signal. Pretty neat. And it works too. With a little patient setting up, you can produce some excellent results which more than justify the inclusion of the Resonators on what is, after all, a sound processor rather than a sound generator.

As an effect, multi-tap delays have been around for quite some time now, and it is perhaps surprising that the Quadraverb was not capable of generating such useful multiple repeats in its original form. No matter, they're here now, and the versatility of their implementation on the Quadraverb Plus is likely to make them a very popular effect indeed. Basically, you can tap into the overall delay span - which may extend to some 1.55 secs - at up to eight individual points and adjust each signal for delay time, volume and pan position.

As you may imagine, this allows you to set up very complex/interesting delay patterns, whilst maintaining precise control over where and when repeats take place.

The last two new effects, Auto-Panning and Tremelo Modulation, share a common identity in that they're both essentially amplitude modulation effects, and to that extent are mutually exclusive - you can't run both simultaneously. Both of them are included within the Quadraverb's EQ-Pitch-Delay-Reverb and Five Band EQ-Pitch-Delay configurations, and both are adjustable for speed and depth. Neither, I hope, require any explanation from me.


WITH THE SORT of "extras" we've been looking at here, it would have been quite easy for Alesis to justify the release of an entirely new effects unit and left owners of existing Quadraverbs to hawk their machines around the shops looking for a good part-exchange deal or chance their arm in the classified columns - in other words, upgrading the hard way. Similarly, it wouldn't have been difficult for them to justify adding at least another 50 quid to the price of the Quadraverb to cover all the extra features, and put it down to inflation. That they have done neither will, I'm sure, reflect very positively on them and ensure some loyal customer support in the years to come.

Though by no means the last word in their respective areas of operation, all these effects are extremely usable and as in so many other areas of hi-tech equipment, help blur the line drawn between creative and non-creative instruments. Recommended.

Price Quadraverb Plus, £399; £12 update for existing users. Both prices include VAT.

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World Party

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Publisher: Music Technology - Music Maker Publications (UK), Future Publishing.

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Music Technology - Apr 1991

Gear in this article:

Studio/Rack FX > Alesis > Quadraverb Plus

Gear Tags:

Digital FX

Review by Nigel Lord

Previous article in this issue:

> World Party

Next article in this issue:

> En Routing

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