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Alesis Quadraverb

Article from Home & Studio Recording, March 1989

The long-awaited new box from Alesis gives the user access to up to four simultaneous high quality effects.

Alesis' first programmable reverb can in fact give you four effect processes simultaneously to create a bewildering variety of treatments.

The time of the multi-effects processor is truly upon us, though to be fair, Roland did get their toe in the water a good while ago with the DEP series. This year we have the ART Multiverb, the Yamaha SPX1000 and the Quadraverb - and that's just before the Frankfurt show!

Let's make it clear at the start that having a unit that's capable of producing four effects at the same time isn't quite the same as having the four individual effects separate. With the exception of some tricks you can do on the much more expensive SPX1000, the chain of effects can only be applied to one signal (mono or stereo in this case). So, if you patch your Quadraverb into an effects send, each channel treated by that send will receive the same multi-effect treatment to a greater or lesser degree depending of course on the setting of the aux send control. In other words, you can't use the reverb on one channel, the delay on another and the pitch effects on another. Having got that one out of the way, what can we do with the Quadraverb?

As its name implies, the unit can produce four effects at a time and these are: reverb, delay, equalisation and pitch effects. In addition, there are specially derived effects such as a very complex Leslie simulation which uses dynamic control of the equaliser section - and all the effects are full 16-bit linear with a 20Hz to 20kHz audio bandwidth. The reverb selection includes true gated reverb effects and the famous Alesis reverb sound with full control over all the important parameters. Unlike some other multi-effects units, the reverb parameters include pre-delay so you don't have to tie up your delay effect to achieve this.

The pitch section is interesting because it isn't just your run-of-the-mill pitch shifter. The designers came to the conclusion that budget shifters always sound dreadful except when used for subtle detuning effects, so rather than compromise the other excellent effects on offer, they limited the shifting to a range that is still more than adequate for detuning. They then added stereo chorus, phasing and flanging to this section - which again keeps the delay section free for other things.

When four effects are used simultaneously, the equaliser section is capable of three-band, true parametric mid operation (control of frequency, cut/boost and bandwidth) with shelving Hi and Lo controls - and even these have variable frequency cut-off points. There are other specialist configurations which we'll be looking at a little later which give five-band parametric equalisation or even 11-band graphic operation. Similar things happen to the delay which starts off offering 400ms in stereo or 800ms in mono - but using a specialist configuration can give up to 750ms in stereo or one and a half seconds in mono. Briefly, these special configurations use fewer effects simultaneously, meaning there is more computing power to be used for the remaining effects.

Aside from this mouthwatering array of processes, the unit is fully programmable with 100 usable memories and there is real time MIDI control over up to eight strategic effect parameters at any one time. There are 90 factory programs in ROM to get you started and these can be modified or overwritten as you like. But because they are safely tucked away in ROM, they can be restored at any time in the future, either all at once or individually. Add to this a very full MIDI implementation, which includes the more usual MIDI program change for selecting effects and the facility to make your own allocation table of Quadraverb patches to MIDI program changes, and you can see that there's a lot more to this box than the 1U case and innocent looking front panel might imply.


When the box containing the Quadraverb first arrived, I thought that Alesis had developed a new 24" rack-mount format but I needn't have worried, the extra long box was to accommodate the external PSU. The black 1U case is styled very much along the lines of the Midiverb II except there is a back-lit LCD window to show the patch titles and editing parameters. Conventional rotary controls are provided for input and output level setting and a basic four-section LED meter shows the input level from —18dB to clipping.

All the other controls are in the form of buttons - 16 for editing/patch selecting and another for the mains power. These buttons are hard plastic with rounded corners and feel much more positive than those used on previous Alesis products. Twelve of the buttons have status LEDs built into them so there is never any doubt as to which mode you're in or what parameter is selected for editing.

Turning to the rear panel, it can be seen that stereo inputs and outputs are provided, though the unit can be used in mono if so desired by using only the right hand input and output sockets. If mono in, stereo out is what's needed, then you can use both outs but just the right input. Signal connections are made on unbalanced jacks which will accept levels from below semi-pro up to +4dBu pro levels still leaving bags of headroom and the high impedance means you can feed instruments straight in. Further jacks are provided so that optional (momentary action) footswitches can be used to bypass the effects or step through the programs one at a time. That leaves a MIDI In and Thru and a four-pin DIN to take the power supply. Outwardly simple then - but how easy is it to use - and just what degree of flexibility can you expect from the onboard effects?

Operating System

Before seeing how the effects may be combined, it is worth spending a few minutes looking at the four basic effects to see what range they cover and what parameters can be altered by the user. The logical place to start is reverb.

Five basic reverb types may be called up to use as starting points: Plate, Room, Chamber, Hall and Reverse. Plate settings have a bright, slightly metallic edge to simulate the studio reverb plates that were invariably used before digital reverb came along, while the Room, Chamber and Hall settings attempt to emulate a more natural acoustic environment. Reverse is the odd one out as it has no natural counterpart and is simply an attempt to create the illusion of a sound being played backwards by applying a reverse envelope to the reverb. Instead of decaying, it builds up from nothing and then ceases abruptly.

Reverb Section

If you think of the reverb section of the Quadraverb as a separate unit (which it isn't really), there are two inputs called Reverb 1 and Reverb 2. Essentially these two inputs can be fed from different points in the signal chain when several effects are being used at once and this adds quite a lot of variety to the results. Reverb 1 can be selected to accept either the pre or post EQ signal, the Pitch output or the Delay Mix input signal. Reverb 2 can be fed from either the pitch or delay outputs. If this seems a little confusing at this stage, don't worry as it will all become clear in the end and the manual does contain some easy to read block diagrams that show how the composite effects behave. A parameter called Reverb Input Mix allows the signals at Reverb In 1 and 2 to be balanced according to taste.

Back now to the land of the familiar. Each reverb setting may be given a degree of pre-delay and you don't have to rob the delay section to get it. But even then, a new and non-familiar parameter raises its head: Pre-Delay Mix. As far as I can make out, this allows you to mix the pre-delayed reverb with undelayed reverb and the effect is that some reverb is audible during the pre-delay period, the exact amount depending on how the mix balance is set.

Reverb Decay is more obvious and in the Reverse mode, the name changes to Reverb Reverse Time so as not to confuse the innocent. Further modifications to the sound may be made by changing the Reverb Diffusion, which dictates how tightly the individual reflections are spaced, and Density which alters the delay between the first reflection and the following body of reverb. Tonal adjustment may be made by varying the High and Low Frequency Decay characteristics independently while gated reverb is achieved by a gating action that comes in when the input signal exceeds —18dB, the lowest LED on the input meter. A Gate Hold time can be set to determine the length of the reverb burst and a further release parameter allows the burst to either cut off abruptly or decay at a rate determined by the user. Interestingly, there is also a Gate Release Level parameter which has the effect of allowing some reverb to be heard, even when the gate is closed. This means that you can create the effect of a gated reverb and a lower level conventional reverb at the same time if you so wish. The reverb decay time depends on the basic reverb parameters you set up before applying the gating. No exact figures are given for any of the maximum parameter values in terms of time but both the pre-delay and decay times seem to offer all the range necessary. The longest reverb time is cavernously huge and can be further lengthened by adding in a long repeating delay.


There are three basic delay types on offer though the maximum delay time depends on which configuration of effects you are using. Ping Pong Delay is a stereo effect where the echoes alternate from left to right at a rate set by the delay time. The maximum delay time is 400ms in the Quad and Leslie configurations and 750ms in the Graphic/Delay and five-band EQ/Pitch/Delay modes. These modes will be covered in more detail shortly.

Stereo Delay has separately variable delay times for the left and right channels and the maximum delay times are as in the Ping Pong Mode. If you only need Mono delay, then you get a maximum of twice the previous delay times.

Apart from the delay time, there is obviously control over feedback to create repeating echoes and the input to the delay may be taken pre or post the EQ. And if pitch shifting is used, you can balance the amount of shifted and unshifted signal fed into the delay.

Pitch Change

Pressing the Pitch button gets you a choice of no fewer than six pitch altering modes and their parameters. The modes are: Mono Chorus, Stereo Chorus, Mono Flange, Stereo Flange, Pitch Detune and Phase Shifter. And the Flange modes may be free running or triggered from percussive sounds. The detuning effects are the same as you would get using a regular pitch shifter while the other Chorus and Flange modes are more than you'd expect from a modulated delay line. Detune simply gives the option of varying the detune amount which can range from a subtle chorus to an out-of-tune effect. The other effects have the usual depth and speed parameters plus feedback for both Chorus and Flanging. Flange may also be set to trigger when the input signal exceeds —18dB. There is a choice of square or triangle for the modulating waveshape and there are separate parameters for the Leslie simulations.

In Leslie mode, you can set the stereo width of the effect and set both the fast and slow speeds of the effect. The Motor Control page allows you to simulate a Leslie speaker with the motor not running and there are ways to control the motor speed via MIDI so that the way in which a real Leslie response can be simulated - including the wind up, wind down time between speeds. It is also possible to adjust the level of the high rotor as compared to the low one.


And so we come to the Equalisation department which is surprisingly sophisticated. Depending on the effect configuration in use, there is the choice of Three-band Parametric, Five-Band Parametric or 11-band Graphic operation. In Three-band parametric mode, the mid section is parametric while the hi and lo filters are conventional shelving types, but still with variable cut-off frequencies. This more basic EQ makes it easy to make things brighter or warmer without having to worry too much about bandwidth or frequency simply by setting the mid flat and using the hi and lo ends as treble and bass controls.

In Five-band mode, the hi and lo end are still shelving but now there are three fully parametric mid sections which gives lots of scope for control so long as you've got the patience to set them all up. When programming, the equaliser frequencies may be changed in 1kHz steps and their amplitude varied in 0.05dB steps which is pretty fine. Likewise, the bandwidth can be moved in 0.01 octave steps. In graphic mode, the frequencies are fixed at: 16Hz, 32Hz, 64Hz, 126Hz, 250Hz, 1kHz, 2kHz, 4kHz, 8kHz and 16kHz.

The System

Even that brief tour through the effects shows what a creative potential this machine has but now we need to see how the user takes advantage of all this without becoming bogged down in an endless series of parameters and values.

" don't have to rob the delay section to get reverb pre-delay or chorusing..."

Despite the apparent complexity, the operating system is very logical and follows similar lines to the HR-16 drum machine. Selecting the Program button lets you use the Value Up/Down buttons to breeze through the 100 programs and the harder you press, the faster the display scrolls! Alternatively, hold down the Program button and select the number of the patch you want directly using the numbered function buttons. You'll find 90 of the 100 memories loaded with factory sounds, some of which are very impressive and all of which provide the basis to create your own customised effects if you're too timid to start from scratch. Programs 85 to 89 are demos featuring the same effects but in different configurations and you can experiment by stepping through the different configuration types to see how different the same effects can sound when patched together differently.

Editing the effects is a logical enough process - the Config button gets you onto the Configuration page and then you can scroll through the options using the value buttons. The options are: EQ > Pitch > Delay > Reverb: Leslie > Delay > Reverb; Graphic EQ > Delay; Five-band EQ > Pitch > Delay and Three-band EQ > Reverb. The first mode is known as the Quadra mode because it gives you access to all four effects simultaneously. The others restrict the effect combination in order to enhance the facilities of the remaining effects.

Once you've decided what configuration to go for, you can then hit the buttons pertaining to the individual effects which will put up the appropriate page in the display and then you can alter the parameters using the Value buttons. Most effects have more than one page so you can use the Page Up/Down buttons, again touch-sensitive, to run through them. In this respect, the programming is much like the Yamaha SPX series. At this stage you must also decide from which point in the chain the effect will be fed and the options are clearly shown in the display.

Once you've set up your effects, you can go onto the Mix page which allows you to route the direct signal through the EQ if you want to and to set its level. It also allows you to set the level of the overall effect compared with the direct sound level, then you can set the output levels of the individual effects used in the patch to get the right mix.

The Name page allows you to name your own patches and the Mod page lets you assign real time MIDI control to various parameters - one page selects the modulation source and the next the destination until you've reached the maximum of eight. Things you might do on this page are tricks like routing the pitch bend wheel, or aftertouch on your synth to control amplitude, LFO speed or some other useful parameter. And, of course, this data can be included in a MIDI sequence so it isn't strictly real time if you don't want it to be. Having edited a patch, you can use the Page buttons to flip between the original and your new version for comparison.

Once you've created the patch you've always dreamed of, you can then store it at any location you wish though it will obviously overwrite anything that was there previously. Even so, the factory patches can always be restored if necessary. And finally, when you want to hear what the input sounds like with no effects added, you can hit Bypass.


MIDI settings are global on the Quadraverb, they're not stored as part of a patch or program. The unit can receive patch changes and control information on any one of the 16 MIDI channels or it can function in Omni mode. There is no MIDI Out as such but the Quadraverb can do a MIDI data dump via its Thru socket. I wonder how long it'll be before someone comes up with a software editing package for the Quadraverb?

The MIDI menu also allows any of the programs to be assigned to specific MIDI program numbers and you can define the range over which the footswitch will work if you want to step through, say, only half a dozen programs before going back to where you started rather than going though all 99. No big deal in the studio perhaps but it could be a life saver for the live performer.

The Sound

As you might expect, the 16-bit linear system coupled with a 20Hz to 20kHz bandwidth results in a pretty clean signal. With a dynamic range of 85dB, it's not as quiet as a CD player but a hell of a lot quieter than even a good analogue tape recorder.

It's hard to attribute any kind of tonal character to the delay effects when what comes out is really a copy of what goes in. But the reverbs are most definitely Alesis, the main differences being the degree of control you have over the effect and the extra transparency that a 20kHz bandwidth gives. Those of you who remember the early Alesis XTC reverb will remember those bright, rather coarse reverbs that sounded so great on vocals. Well, now you can get that effect simply by programming a less diffuse reverb patch with plenty of top. If you're after a dense, natural sounding reverb, those are in there too with plenty of variation. The machine is just as happy simulating a broom cupboard as it is a concert hall. As we have come to expect from Alesis, the only unnaturally ringy reverb effects are the ones created that way on purpose.

In the Pitch department, the detuning effect is quite wonderful as are the chorus and flange effects but I did notice a little glitching on the triggered settings as the LFO reset, rather in the same way as on the Midiverb II. This would be completely masked on percussive sounds but on other material, it might be better not to use the triggered option. Likewise on the real time 'MIDI control of detuning' patch, there was a definite glitching if the pitch was changed during a sustained sound. No problem though if the pitch was changed between sounds. In any event, I feel that there are plenty of good control applications available so you can always steer clear of the dubious ones.

I must admit that I like Leslie sounds and those supplied are extremely convincing, especially with the authentic motor speed changes. The equaliser too is more effective than most people are likely to need though to be honest, I couldn't be bothered trying to set up a five-band parametric to tailor the direct sound - I'd rather use an analogue equaliser with knobs on. But used within a chain of effects for affecting the tonal quality of the treatments, even the three-band equaliser can do wonders. Where this sophisticated EQ is going to come in useful is in the area of live performance or for the instrumentalist who wants to bring his or her own Quadraverb into the studio to play through without using the desk's aux sends. In this way several instrument tonalities could be set up and I can see guitarists being particularly interested in this application.

But the real strength of this device is in the quality of the composite effects. Patch 56, Quadreamverb, is a real beauty for atmospheric piano and would be enough to make any heavy metal player hang up his leather jockstrap in order to take up writing new age stuff. It combines long echo and reverb with a little subtle EQ and a touch of stereo chorus to create a huge, ethereal soundscape.

Reverbed Leslie is applicable not only to organ sounds but to guitar or synth while you can easily create your own double tracking vocal patches using short delays, a little pitch shift and a dash of reverb. The combinations are endless, but because coming up with something really good can take a little time, you're more likely to build yourself what is in effect a bank of presets and then use them with little or no modification.


This has been quite a long review, yet I feel that I've only just scratched the surface. It is the variety of options for configuring the four effects that is so difficult to describe, both factually and in terms of the effect on the sound being processed.

Some people will criticise the Quadraverb for not including a full function pitch shifter but my own opinion is that Alesis were right to omit it. The quality of the existing effects is so good that it would have been senseless to include a half-cocked shifter - and unless you spend a great deal of money, you're bound to get glitching.

The fact that you have Alesis quality reverb in an editable form is probably a big enough incentive for most people to take the Quadraverb seriously, but once you've played with it for a while, it's evident that some of the combination programs are greater than the sum of their parts as far as the subjective effect is concerned. Particularly sensible is the way that the effects are subdivided so that you don't have to rob the delay section to get reverb predelay or chorusing and the EQ is serious stuff, not just a top cut or something similar. The effects you can create would normally take a lot of separate gear and a lot of patching to set up so if you've already got a basic reverb and a compressor, the Quadraverb might sensibly be the next item of equipment to put on your 'must have' list. Despite the many options, it's very easy to use and the effects are first class. Any niggles are very minor and I'm not going to repeat them here - you'll have to read the rest of the review.

And to really finish off, the cost of this machine is little more than the original price of the Midiverb II yet it offers so much more in terms of sound, programmability, MIDI control and technical specification. There is competition, but when you take the quality and the price into account, the Quadraverb is going to make an awful lot of friends.


Frequency Response16Hz-20kHz
Dynamic Range85dB
Distortion1% typ. 1k OdB
Signal Levels Input -10 - +20dBv peak
Output wet +14dB
Output dry + 20dB
Input Impedance1 Megohm each channel
500kOhm mono
Processor Speed24,000,000 instructions per second
Conversion Scheme16-bit linear PCM

The Alesis Quadraverb costs £449 inc VAT.

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Realistic Arrangements: Vocals

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Publisher: Home & Studio Recording - Music Maker Publications (UK), Future Publishing.

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Home & Studio Recording - Mar 1989

Gear in this article:

Studio/Rack FX > Alesis > Quadraverb

Gear Tags:

Digital FX

Review by Paul White

Previous article in this issue:

> Realistic Arrangements: Voca...

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> Ian Anderson

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