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Alesis Q2

Multi-effects Processor By Paul White
Published October 1994

Paul White finally gets his hands on the long‑awaited big brother to the Alesis Quadraverb and Quadraverb+.

Time seems to fly by in some situations, (when you're editing computer sequences, for example), whilst on other occasions it hangs around in glutinous pools (particularly in dentists' waiting rooms), apparently in no particular hurry to go anywhere. This certainly seems the case with the time elapsed since the release of the original Alesis Quadraverb, which seems to have been with us since shortly after the last of the dinosaurs looked into the night sky and commented that the mountain‑sized chunk of luminous rock, approaching at many times the speed of sound, looked rather attractive and — briefly — hoped it would come closer so they might get a better look at it.

The longevity of the Quadraverb might cynically be attributed to the fact that ADAT has tied up the majority of Alesis' R&D effort for the past few years, but a fairer interpretation of the situation must include the fact that the Quadraverb has one of the most friendly operating systems around. And the Quadraverb isn't about to be pensioned off yet, because the Q2 doesn't replace it, but rather provides a more sophisticated (and more costly) alternative.

The Technical Side

Briefly, the Q2 is a general‑purpose, stereo‑in, stereo‑out multi‑effects unit. It also features ADAT format and optical digital I/Os, plus a BNC clock input socket, which enables the output of the unit to be recorded directly to any pair of tracks on an ADAT — without leaving the digital domain. For Quadrasynth owners, the digital input also means that their instrument can be fed via the Q2, again all digitally. The analogue/digital conversion employed for the benefit of those not recording digitally has a similar spec to that used in the ADAT — the input is a 16‑bit Sigma‑Delta system with 128 times oversampling, while the output stage is an 18‑bit Delta‑Sigma device with 64 times oversampling. The normal sampling rate is 48kHz (the same as the ADAT), but this may be varied from 40.4kHz to 50.8kHz under external control, presumably to allow for varispeed operation when linked to an ADAT. The outcome is a frequency response extending from 20Hz to 20kHz, with a quoted dynamic range in excess of 90dB (A‑weighted). Interestingly, the analogue input jacks may be used balanced or unbalanced; in balanced mode, they offer an impedance of 20kΩ, while in unbalanced mode, they jump to a high 500kΩ, which is high enough to allow an electric guitar to be directly connected. The outputs are servo‑balanced and, again, may be used unbalanced if preferred.

The Q2's 1U package is both simple and stylish, with a gently curved front panel. Power comes from a Quadraverb‑style external PSU, and though these things are a pain, it does mean that the depth of the case can be kept down to six inches or so. For patch selection or editing, a Value/Enter wheel takes over most of the functions normally ascribed to cursors, and the usual enter button is replaced by combining the wheel with a push switch, so that in order to confirm an entry, all you have to do is press in the wheel. All the remaining keys are single‑function ones, with rocker‑style cursor keys used for Block and Parameter selection. The operating system is very intuitive — sufficiently so, in fact, for anyone with previous multi‑effects experience to be able to hack through it without even looking in the manual.

Constructing Effects

One outstanding feature of the Q2 is the larger‑than‑average LCD window, which contains a custom display. In addition to providing all the usual patch name and parameter data, this includes a block diagram of the currently selected effect, including the way the various effects blocks are connected together. As with most multi‑effects units, various basic effects are combined to produce the final composite effect, but whereas most processors restrict the way these can be connected, either by providing a limited number of 'pre‑patched' algorithms or offering no variety at all, the Q2 allows the user to create custom patching arrangements with the aid of the graphic display.

In theory, up to eight blocks may be used simultaneously, but depending on the nature of the blocks, the actual maximum number may be somewhat less, as the available processing power isn't up to generating, say, eight mega‑complex reverbs wired in series! Furthermore, there are some effects that can't ever be used simultaneously, namely Phasor, Stereo Lezlie and Ring Modulator. That's because the Q2's housekeeping microprocessor (the one that looks after the display, editing and so forth) has to lend the effects DSP a hand to produce these particular effects — and apparently it only has one hand to lend.

At first glance, there appear to be only four basic effects types on offer: Reverb; Delay; Pitch and EQ. However, each block provides a range of alternative effects, so that when you delve into Pitch, for example, you find mono, stereo and quad choruses, mono and stereo flanging, phasing, mono and stereo Leslie, pitch shifting and ring modulation. The manual provides a comprehensive table for each effects block, so you can see at a glance what variations are available and exactly what parameters (along with their ranges) can be edited for each variation. Most blocks can be used more than once in the same patch, though a few of the effects have limitations in this respect, because of the amount of processing power required. A table at the back of the manual shows what percentage of the overall processing power is used up by each effect type.

Up to eight parameters can be controlled simultaneously in real‑time over MIDI, and again, a table of modulation destinations running to some one and a half pages is printed in the MIDI section of the manual. In addition to the usual MIDI controllers, MIDI notes and velocities may also be used. Furthermore, there are two internal non‑MIDI controller sources, or Local Generators, derived from the incoming audio signal level and envelope. The modulation routing is arranged in matrix form, so that the same source can modulate more than one destination if required.

Of course, MIDI may also be used to select patches using program change commands, but as there are 100 presets (actually 99 plus a bypass setting) and 100 user patches, there is provision to create an assignment table, so that up to 128 patches (user or preset) can be allocated to the desired program numbers. For live work, rear panel jacks are fitted for use with optional Bypass and Advance footswitches, and the latter can be used to step through a range of consecutive patches selected by the user. Once the highest selected patch is reached, the next press on the switch flips back to the first patch in the series.

Two MIDI sockets are provided, one for In and one for Out/Thru. The Q2 can be set to work on any MIDI channel, and SysEx dumps can be used to store/transfer either individual patches or the whole user memory.

The Effects

It seems that once you get behind the new operating systems and the improved technical spec, the available effects differ very little from one multi‑effects machine to another. This is also true of the Q2, though there are one or two unusual inclusions, and there's certainly no shortage of variations on all the standard effects. For a full listing of the effects types, see the side panel elsewhere in this article. Most of the effects will be instantly familiar, but it's worth mentioning the less obvious ones.

To begin with, there is Resonator, which is part of the EQ block. This is really a very short delay with a high level of feedback, so that whatever you feed into it 'rings' at a single frequency or pitch. This pitch may be set to any musical note, but I couldn't find any way of controlling the pitch over MIDI, which you can do with the Resonators in the Quadraverb. Also in the EQ section is a stereo simulator, and though no explanation is provided as to how this works, I'll stick my neck out and say that it sounds like comb filtering, where one set of filters is applied to simulate one side of the stereo signal, and the exact opposite filter response is applied to simulate the other channel.

The Pitch section includes a Leslie simulator, which is designed to emulate an organ tone cab with rotating speakers or baffles. There's also a ring modulator, which modulates the input signal using an internally generated waveform at a fixed frequency. Because a ring modulator produces only sum and difference frequencies, with none of the original signal present, the output is rarely musically usable, but it is good for creating unusual percussion, special effects and robotic voice sounds. The original Dalek voices were created using a simple ring modulator and an oscillator.

Most of you will be familiar with mono and stereo delays, including multitapped delays (up to five independent taps in this case) and ping‑pong delays that bounce from one side to the other, but the Q2 also includes tap‑tempo delays, which allow delay times to be set up by feel rather than by using a calculator. Having said that, the delay time readout also includes a tempo in bpm (not in multitapped mode of course) along with an indication of what subdivision of a bar the delay is currently set to — a very nice touch. To use the tap‑tempo facility, one of the two footswitches can be designated (via the Global parameter setup pages), or the Value/Enter knob can be pushed. In all modes, the maximum delay time is a very generous five seconds.

You can call up no fewer than 14 reverb types, and in addition to the usual 'real spaces', gated reverbs and reverse settings, there's a spring reverb simulation, for those who think that nostalgia isn't what it used to be. All the stereo 'real space' reverb settings come in two types, and it's worth noting that type 2 uses much more processing power than type 1. Type 1 reverbs are, therefore, more suitable for inclusion in a busy chain of effects, whereas type 2 reverbs sound better when used in stand‑alone reverb patches or multi‑effects patches with just a few other blocks.

You can call up no fewer than 14 reverb types, and in addition to the usual 'real spaces', gated reverbs and reverse settings, there's a spring reverb simulation, for those who think that nostalgia isn't what it used to be.

As you'd expect from a serious unit such as this, all the expected reverb parameters pertaining to early reflection, pre‑delay, HF roll‑off, decay time and so on are available for editing, though I take exception to two of the parameter titles, carried over from the Quadraverb, which are just plain misleading. Density, for example, relates to the position of the first reflection or discrete echo, whereas you'd normally expect density to relate to the number of reflections in a given period of time. The term Diffusion is used to describe the reflection spacing (density in real‑speak). Diffusion is normally understood to mean the rate at which the density builds up.

A new parameter is Reverberation Swirl, which adds a chorus‑like effect to the reverb to smooth out the decay. Though achieved in a different way, this is probably designed to create the same effects as the Spin and Wander parameters used in some Lexicon reverb algorithms. Another new parameter (used only on Plate 2 and Chamber 2) is Reverberation Attack, which seems to add more energy to the very start of the reverb, making it more aggressive.

In Use

After only a brief perusal of the manual, I was happily bolting together Blocks, stringing bits of virtual cable between them, and fiddling with the parameters. Whether or not the result was a legend in its own decay time is a different matter, but the point is that editing is easy. Each of the blocks is mono in with a stereo out, plus a mix out. One or more connections may be made to each block (the input acts as a mixer), and the outputs may be split to feed more than one destination if required. There are three possible destinations from a given block: the inputs of any other blocks in the chain (not just in order), either of the two main outputs, or even the input of the current block (in order to feed a block back on itself), as long as you set the gain low enough to prevent it turning into an oscillator. Surplus connections can be deleted as easily as they are created, and the beauty of the system is that the front panel display shows you exactly what is connected to what. I must confess, though, that several of my attempts to string more than four effects blocks together were met by a message informing me that my credit had expired in the processing department, and this is very frustrating when you are trying to do something that you know is perfectly rational.

I'm happy to report that the quality of all the effects is quite excellent, with the exception of the pitch shifter, which, though perfect when used for detuning, is about as warbly as they come when it comes to setting up whole intervals. The reverb algorithms are streets ahead of those in the Quadraverb, and although one delay sounds much like another, the tap‑tempo and tempo‑related readouts make the delays very easy to set up. There's no specific provision to emulate tape echoes, but by taking a delay output through an EQ block to shave some of the top end off, and maybe through a modulation effect to add just a hint of wow and flutter, you can get pretty near. The more ambitious could put an EQ block between the delay output and the delay input and use the gain settings to provide the required feedback.

All the modulation effects are rich and musical (unless you go over the top with the rate or depth settings), and by combining two or more modulation blocks together, you can create some beautifully fluid chorus patches. The flanging still doesn't quite have the magic of real tape flanging, but the phasing effects are really first rate.


Because of the open‑ended routing system, the Q2 is a machine with hidden depths that only the most dedicated effects programmer is likely to explore fully. The more casual user in search of new and different effects is less likely to be surprised by the nature of those on offer here, though few can fail to be impressed at the actual effects quality. Plus points for the Q2, other than its truly hi‑fi performance, are the intuitive editing system and the large, informative display (even so, there's a limit to what you can show on a 1U display, which means that the block diagrams are fairly small and detailed — so it's essential that the Q2 is set up somewhere near eye level, otherwise you'll go mad trying to edit it). The digital I/O is also a worthwhile bonus for those using ADAT or an Alesis AI‑1 sample rate converter, which would allow the output to go straight to DAT or hard disk.

The Q2 has been a long time coming, and now that it's here, it scores very highly in most areas. It offers slightly more flexibility than the Quadraverb, the sound quality is noticeably better, and the only disappointments are the omission of the Quadraverb's Lexicon‑style MIDI‑playable resonators, and the somewhat perfunctory pitch shifter. I know that seam‑free pitch shifting is very hard to do, especially cheaply, but somehow I thought that if anyone would crack it, it would be Alesis.

To sum up, then, the Q2 isn't a huge leap forward in the type of effects that can be created and combined, but when it comes to quality and usability, there's no denying that it sets new standards within its price range. I wonder if it'll enjoy such a long and illustrious life as the Quadraverb?

Routing Options

Because of the flexibility with which the Q2's effect blocks can be arranged, it is possible to set up different chains of effects sourced from the left and right inputs, making true stereo processing possible. These independent chains may each end with a stereo reverb, so you aren't forced to work in mono when creating two different multi‑effects at the same time.

A more exciting possibility, however, is to create a multi‑effects patch where one channel is processed differently to the other, to create a dramatic stereo effect. A common example of this is to delay just one side of a stereo reverb, so as to make the reverb appear to move from one side to the other as it evolves, but there are plenty more things to try, such as using different EQ on the two channels, or adding mono chorus to just one side.

Individual effects blocks can be fed back to the inputs of other blocks or to themselves, but in any patch where a feedback loop is created, the internal levels must be set very carefully in order to prevent the patch from oscillating.

The phrase 'Limited only by your own imagination' is probably about the most over‑used cliche there is when it comes to effects units, but in the case of the Q2, you're also limited by the amount of processing power and memory available. The Q2 seems to have plenty of memory to go round, even when creating 5‑second delays, but the processing power has to be used more carefully. For example, the Mono Room reverb takes up 28% of the processor's capacity, while the Large room hogs a staggering 91% of memory, leaving Room only for a basic chorus delay or EQ block. The more complex equalisers also devour memory, with the 5‑band graphic and 4‑band parametric each taking up more than one third of the processor's capacity.

Effect Types


  • Low‑pass Filter.
  • Band‑pass Filter.
  • High‑pass Filter.
  • Low‑pass Shelf.
  • High‑pass Shelf.
  • 1‑band Low Parametric.
  • 1‑band High Parametric.
  • 2‑Band Sweep Shelf.
  • 3‑band Parametric.
  • 4‑Band Parametric.
  • 5‑band Graphic.
  • Resonator.
  • Mono Tremolo.
  • Stereo Tremolo.
  • Stereo Simulator.


  • Mono Chorus.
  • Stereo Chorus.
  • Quad Chorus.
  • Mono Flanging.
  • Stereo Flanging.
  • Phaser.
  • Mono Lezlie.
  • Stereo Lezlie.
  • Pitch Shifter.
  • Pitch Detune.
  • Ring Modulator.

DELAY BLOCK (All delays 5S max)

  • Mono Delay.
  • Stereo Delay.
  • Ping Pong Delay.
  • Multi‑tap Delay.
  • Tap Tempo Mono Delay.
  • Tap Tempo Ping Pong.


  • Mono Room.
  • Room 1.
  • Hall 1.
  • Plate 1.
  • Chamber 1.
  • Room 2.
  • Hall 2.
  • Plate 2.
  • Chamber 2.
  • Large Plate.
  • Large Room.
  • Spring.
  • Nonlinear.
  • Reverse.


  • Intuitive graphic interface.
  • Very high sound quality.
  • ADAT digital I/O.


  • Perfunctory pitch shifter.
  • External PSU.
  • Processing capability is frequently used up by the time four or five effects Blocks have been added.


A mid‑price effects unit that delivers all the standard effects to a very high quality, and with the minimum of fuss. Will appeal to the serious user who is prepared to pay that little more for a quantum leap in quality.