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Tuesday, November 5, 2013

Alesis QuadraSynth

64-note Polyphonic 76-key Synthesizer

Reviews : Keyboard


MARTIN RUSS looks at the long-awaited new keyboard from Alesis and finds that it takes an alternative approach to just about everything...


In a world where everything is held up to be new and different, it sometimes seems that uniformity is the real result. So if I ask you to describe an effects unit, you think of a 1U-high rack mounting box, with a 2x16-character green backlit LCD, some knobs and buttons, and a red LED display for the program number. Master keyboards get much the same reaction: heavy, lots of aluminium extrusion, no internal sounds, a large LCD with softkeys and a data wheel, and so impressively complicated and capable that you never quite get around to working out how to use it properly. But now and again, someone with imagination (and nerve!) comes up with a product which dares to be different -- which can only be the cue for a review of the Alesis QuadraSynth.

The QuadraSynth is unusual. It has a light action 76-key E-G keyboard, featuring monophonic (channel) pressure, and sensitive to both attack (Note On) and release (Note Off) velocity. The grey plastic casing is light, rigid and tough, and even incorporates a carrying handle. The rotary controls are all rubber-coated, which makes them non-slip -- even the pitch and mod wheels, which are turned round slightly so that they are still easy to use on a long keyboard. There is no on-board sequencer, no disk drive, no user sample RAM, and no softkey-driven graphic LCD with sophisticated computer windowing interface. There are only two operating modes: Program, where you play individual programs which are made up of up to four individual sounds; and Mix, where you can stack and split up to 16 programs at once, multitimbrally across 16 MIDI channels, and yet still have 4-voice polyphony.




The June 1993 issue of Sound On Sound has a fascinating article which takes you inside the mind of Marcus Ryle, one of the team at Fast Forward designs responsible for the conception and realisation of the QuadraSynth, in co-operation with Alesis. Marcus and his partner Michel Doidic also worked on some of the classic Oberheim synthesizers, like the Matrix 12, and were involved in the design of the ADAT digital tape recorder and the Quadraverb effects units. So it comes as no surprise that the QuadraSynth has a four-channel digital optical interface directly to ADAT, as well as a sophisticated effects section.

The problem with talking to a magazine about a product, and then releasing it almost a year later, is that you give away one of the carefully guarded secrets of the electronics industry. Products do not appear overnight! It can take several years for a product to move from initial designs to the final product. Reading the interview, it is remarkable how much of what is described is present in the final instrument. The designers of the QuadraSynth seem to have had a clear vision of what they wanted from the beginning.




Program Mode lets you play single sound patches, known as Programs in Alesis-speak. Each Program can be made from up from a stack of up to four separate 'Sample & Synthesis' sections, and each one uses up one note of polyphony. With 64-note polyphony, this means that a four-sound stack is 16-note polyphonic. Each program also has a linked effects patch -- select the Program and the effect is selected too. There are 128 Preset Programs and effects, as well as 128 user-programmable Programs and effects. You can have an effects patch linked to several programs, although the effects patch remains separate, so if you edit it, then it will affect each linked program. Of course, you can always edit an effects patch, store it in a new location, and then re-link it into the program. This system is easy to use, and simple to look after.

Mix Mode is a collection of up to 16 programs -- a multitimbral setup. Each Program can be assigned to a separate MIDI channel, can be split, layered and have its level, panning and effect send level controlled individually. The layering is in addition to any already present in the program patches, so a four-sound Program with 16-note polyphony could be stacked up with 16 other similar Programs to give a one-note polyphonic monster sound, if desired. The effects assignment can be linked to either the Mix itself, or to one of the Programs within the mix -- only one effect patch can be active at once. There are 100 Preset Mixes and 100 user-programmable Mixes.

Depending on the size of RAM card in the QuadraSynth's rear-panel card slot, you can store up to nine sets of Programs, Mixes and all the other Global settings on one card. ROM cards will provide additional banks of programs and/or mixes. Sound Technology tell me that ROM cards can also be used to provide additional samples.




The QuadraSynth uses QSComposite Synthesis, which is another way of saying that it is a Sample & Synthesis (S&S) instrument. ROM samples are processed by a low-pass filter and envelope shaper, and then pass to panning and effects sections for subsequent mixdown onto four output busses: two main and two auxiliary.

There are 16 named groupings of samples: Piano, Organ, Keyboard, Synth, Waves, Bass, Guitar, Brass, Woodwind, String, Ensemble, Ethnic, Voice, Sound FX, Drums and Percussion. There are over 300 different samples, ranging from realistic pianos, marimbas, strings, basses and flutes, to synthetic FM clavinets and basses, synthesizer sync sounds, resonant filter sweeps, additive and wavetable sounds, as well as a collection of drum and percussion sounds. Some of the samples are multisampled (pianos and strings, for example) whilst some are also sampled at different velocities (electric pianos). The range covers the usual mix of vintage, classic, contemporary and obscure -- but with a marked absence of atmospheric loops. If you like rippling water or percussive rhythms, then this is not the sample set for you. This is a set obviously designed for good, solid, usable sounds, and thus less than exciting, and none too glossy.

Bearing in mind Fast Forward Designs' connections with Digidesign, it comes as no surprise that the majority of the samples are of very high quality -- perhaps the best I have yet heard, although the major low points were the 'Flute' sound, which is about the worst I have yet heard, and those munchkinised voices... Most of the samples had attack segments with looped sustains, and only a few had just looped waves or just attacks.




In an S&S synthesizer, the samples are just the raw material for making sounds. Often, it is what you can do in the synthesizer processing section that makes all the difference. The QuadraSynth's lack of a resonant filter is unfortunate, since it limits the use of any resonant filtering to just a few pre-prepared samples. The velocity cross-fading is a bit of a mixed blessing; it provides 13 choices, but these are made up of preset groups of two-way, three-way and four-way splits. You get nice cross-fades instead of sudden switches between samples, but then you are effectively locked into a single preset for each split.

The Tracking Generator continues the theme of good features mixed with 'less good' features. 
Tracking generators let you map controllers in non-linear ways -- so a simple modulation wheel up and down movement can be changed into a more complex up and down modulation, or simplified into an on/off switch action. Velocity curves can be reworked to suit your own preference, and you could even remap note numbers -- although this is not as useful as you might imagine. The tracking generator has 10 steps, and the mapping curve is interpolated from the points you define. This is where a graphical display would come into its own, and unfortunately the custom LCD only allows the display of four sliders at once, which makes the tracking generator much less easy to use than it ought to be. Computer-based graphical editors will make this a popular feature with programmers.

One very novel feature is the Trigger Rate Follower, which converts how fast notes are being played on the keyboard into a controller. So you can program features like LFOs which go faster the faster you play, or a filter that opens up as you play faster. Alesis provide separate LFOs and Envelopes for the Pitch, Filter and Volume sections, and the ability to delay envelopes means that you can assemble simple time-sequences of samples. A host of modulation sources and destinations, and a comprehensive 'matrix' switching arrangement allow you to connect up to six controllers (more would be even better!) Yet another bit of inventiveness worth mentioning is the idea of Sound Overlap -- the way in which you designate the effective polyphony of the instrument. A single control lets you vary how notes are assigned, which avoids the complexity of reserving notes, or being forced to choose between the 'cyclic' and 'reassign' types of note allocations that some instruments confront you with. Best of all, Sound Overlap is settable for each Program! Overall, the synthesizer section has a mix of innovation and lots of detail, which means that there is lots of scope for programming your own sounds.

Although the editing of the sound parameters is very detailed, with lots of values to think about, there is also a very clever way of presenting the contents of a Program. There are two edit modes: in Edit 1, you get up to four parameters which can be changed using the four Quad Knobs, so you can do quick edits of related parameters; whilst in Edit 4, you see the same parameter for all four sounds which make up a Program -- so you can quickly see how one sound relates to the others. Since many Programs use two or more sounds at once, this is a welcome way of simplifying the editing process, and it saves a lot of jumping back and forth between pages. Full marks for innovation here, and I hope that other manufacturers will copy this idea!

As with most S&S instruments, the QuadraSynth has two synthesis modes: Keyboard mode, where a sample is applied to the whole keyboard range, and the full synthesis capabilities are available; and Drum mode, where lots of samples can be arranged across the keyboard range, but there is a more restricted set of processing available. In the QuadraSynth, the drum mode offers more parameter controls than most. Individual controls are provided for level, pan, effects send (!), pitch, filter (!), note number, envelope decay and muting group. This is very similar to the much-praised system used on Yamaha's RY30 drum machine, and not what you expect in an S&S instrument. There is one minor limitation to the drum mode -- you can only have 40 different drum sounds in one sound patch!




Since the QuadraSynth comes from the same designers as the similarly named QuadraVerb, you would expect that the effects section would be impressive, and it is. Up to four separate effects sends are available, and the effects processing is almost always more than just four simple effects.

The effects are divided into three types: Pitch effects like chorus and flanging; Delay effects like echo; and Reverb effects, including various room types and special cases like gated and reverse. There are three basic configurations, which determine how these three sets are connected together:

• 4 Sends to 1 Reverb. Three sections made up from a Pitch and Delay effect, as well as a fourth Delay-only effect, are all connected to one common Reverb section.

• 4 Sends to 2 Reverbs. One Delay, Pitch and Reverb section, in parallel with a Pitch and Reverb section.

• 4 Sends to 1 Reverb with 'Lezlie'. One section made up of what Alesis call a 'Lezlie'- type effect followed by a Delay effect; two sections made up from a Pitch and Delay effect; as well as a fourth Delay-only effect, are all connected to one common Reverb section.

Each effect has comprehensive control over parameters and there is an excellent modulation function: you can patch two modulation sources to any of the controllable destinations, although Alesis warn you that changing some effects parameters 'live' may cause glitches in the audio output.

Because the effects are so strongly associated with particular sound patches, rather than a separate afterthought, it is difficult to think of them in isolation. Unlike some synthesizers, where the effects are noisy, weak and often abandoned in favour of outboard processors, the QuadraSynth effects are quiet and powerful -- a very useful part of the synthesizer processing. Having four separate sends to four very different effects setups is very flexible, especially in a multitimbral mix.

Mentioning high quality prompts some thoughts on the volume control and digital interfacing on the QuadraSynth. Alesis say that the best dynamic range is obtained with the volume control turned full on, and this is consistent with current digital design practice. The idea is that you use an analogue-to-digital converter to measure the position of all the front panel controls, and then use the resulting digital values to control the synthesis digitally. So the volume control just controls the size of the output that is presented to the digital-to-analogue converters, and does not actually have the audio signal anywhere near it. Having almost no audio wiring inside the casing means that there is little opportunity for noisy pots, distorted output amplifiers and interference pickup, but the optical output on the QuadraSynth enables an even more direct digital connection, by allowing the instrument to be cabled to a ADAT digital recorder -- the main and auxiliary outputs turn up as four channels on the ADAT. This offers the possibility of an all-digital path from synthesizer to recorder, with no analogue audio in between.




Whereas most master keyboards are a maze of complex MIDI functions, Alesis have chosen a much simpler route. The Mix Mode allows you to set up how the QuadraSynth responds over 16 MIDI channels, and this is achieved by selecting the program and then using two dedicated buttons to increment or decrement the MIDI channel. With 64-note polyphony, this could conceivably be almost the only sound module that some users would need for simple projects or demos. You can set up the unit to receive MIDI information on any of the 16 channels, and controlling the transmit channel or channels is again merely a matter of using the MIDI channel buttons and looking at the display. The underline shows the currently selected MIDI Channel, whilst bars over each channel number indicate the receiving or transmission of MIDI information. Setting it up to transmit on more than one channel at once, or just on one channel, is dealt with by using just one global parameter.

Sequencers have the advantage of graphical interfaces, special functions to deal with System Exclusive data, MIDI Clock synchronisation and other complex MIDI control operations. The QuadraSynth wisely concentrates on providing an easy-to-use 76-note keyboard, with lots of polyphony, for use as a 16-part multitimbral sound module. For about 80% of users, I reckon that is probably the perfect division of tasks.




The high quality audio output makes this one of the cleanest and most crisp-sounding S&S synthesizers I have yet heard. It offers a classy, but very conventional set of sounds in an unusual package, and has gone a long way down the 'ease of use in live performance' route -- you just choose a sound and play. The large polyphony and stacking capabilities make it a powerful synthesizer for big and bold or rich and expensive sounds, but I wonder if the basic S&S approach and unexciting sample set incorporate enough innovation to make it stand out above the competition, where 'vector-style' evolving timbres and sample/wave sequencing give 'performances from single note' sounds which sell instruments, even if they are unusable in a recording or performance context. The QuadraSynth feels much more like a basic musician's workhorse than an over-sophisticated designer synthesizer.

What makes the QuadraSynth impressive is its combination of 76-note keyboard and 64-note polyphony, at a price which seems rather too low. The LCD and filter resonance may be the casualties of cost-cutting, but the sound quality and ease of use go quite a long way towards compensating. Words like 'a qualified bargain' spring to mind, so if you are looking for a very capable keyboard companion to a sequencer, and you do not like the traditional 5-octave bottleneck, then the Alesis QuadraSynth could be the one to go for. I would certainly prefer to be lugging this around from gig to gig instead of my current heavy monster! 

Published in SOS May 1994

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