Alesis Fusion Tutorial
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Alesis Fusion Tutorial

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Download this manual See also: Reference Manual, User Manual
ALESIS FUSION
The basics....
Since the early days of analog synthesisers back in the 60s, an analog synthesiser can be
broken down into just a handful of basic components. These are:
•
SOUND GENERATORS
•
SOUND PROCESSORS / MODIFIERS
•
CONTROLLERS
The sound generators take the form of OSCILLATORS and also NOISE GENERATORS
The sound processors / modifiers take the form of FILTERS and AMPLIFIERS and also RING
MODULATORS and, these days, effects units such as REVERB, DELAY, CHORUS, etc..
The controllers take the form of ENVELOPE GENERATORS, LFOs (LOW FREQUENCY
OSCILLATORS) plus 'real-time' controllers such as KEYBOARD, PITCH BEND and MOD
WHEELS, VELOCITY, AFTERTOUCH, etc..
Don't worry about the jargon and terminology for now - we will look at these in detail throughout
the course of this tutorial.
The history....
In the early days of synthesisers, all the different components mentioned above were available
as separate 'modules' and were connected together using 'patch cords':
Thus, to make a sound, you would typically patch a cord (cable) from the output of an oscillator
to the input of a filter. You'd then patch a cord from the output of that filter to the input of an
amplifier and the whole lot would be controlled by various controllers (all patched in with various
cords). Apart from being big, bulky and expensive (not to mention somewhat temperamental
and unreliable!), this made them unsuitable for use live on stage because each sound had to
be made from scratch (there were no patch memories in those days!).
Introduction
ANALOG SYNTHESIS TUTORIAL
Page 1

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  • Page 1 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL The basics..Since the early days of analog synthesisers back in the 60s, an analog synthesiser can be broken down into just a handful of basic components. These are: • SOUND GENERATORS • SOUND PROCESSORS / MODIFIERS •...
  • Page 2 Which brings us to the present day. The VA (virtual analog) synth in Fusion is a powerful engine that offers a truly comprehensive specification that outperforms almost all of the old analog synths of yesteryear whilst retaining the warmth and character of those old classics.
  • Page 3 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Voice architecture..The typical signal flow of a typical analog synth was pretty much defined with the MiniMoog and is something like the following: Simplified block diagram of a typical analog synthesiser Two (or more) oscillators generate the basic sound and these are fed into a filter which allows you to manipulate the tone, often quite dramatically.

  • Page 4: The Oscillators

    ALESIS FUSION ANALOG SYNTHESIS TUTORIAL SOUND GENERATORS - WAVEFORMS The oscillators..The oscillators define the basic pitch and tone of an analog synth sound. You can think of them pretty much like the ‘strings’ of the instrument. They generate a basic waveform at a pitch set by a combination of tuning controls, the keyboard and different controllers.

  • Page 5: Square Wave

    ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Square wave The square wave is another very bright waveform but sounds different because it only contains odd numbered harmonics (X3, X5, X7, etc.). As a result it sounds ‘hollow’ and not unlike a clarinet. It is useful for many sounds that require that quality and is very useful for reinforcing bass sounds, especially when tuned an octave down from the other oscillator(s).
  • Page 6 ‘hissy’ and suitable for wind and breath sounds whilst pink noise has more ‘rumble’ and is useful for thunder and surf sound effects. Fusion also offers a red noise option which is even more biased towards the low frequencies and is seriously menacing and ‘rumbly’.
  • Page 7 ‘mush’. Fusion’s VA synth has three oscillators. NOTE: On Fusion, it is possible to pan each of the three oscillators separately so that as well as ‘fattening’ a sound with detune, etc., you can also ‘spread’ the sound across the stereo image with judicious use of oscillator pan.

  • Page 8: Pulse Width Modulation (Pwm)

    Controlled by the modwheel, the pulse width can become a performance parameter. However, unlike most synths, Fusion also provides the same facility with the sawtooth and triangle waves and instead of a switched choice between one or the other, you can ‘morph’...
  • Page 9 All synths offer some way of balancing the relative levels of the various oscillators. Some two oscillator synths have a simple ‘balance’ control (which can be inflexible) whilst other synths have an oscillator mixer. Some, however, (like Fusion) simply have an output level for each of the oscillators.

  • Page 10: Low Pass Filter

    ALESIS FUSION ANALOG SYNTHESIS TUTORIAL SOUND PROCESSORS / MODIFIERS Filters If the oscillators are the ‘strings’ of an analog synthesiser, the filter is the heart and a synth can stand or fall on the quality of its filter(s). Put simply, the filter is one big, drastic tone control that can modify the basic sound generated by the oscillators.

  • Page 11: High Pass Filter

    ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Highpass filter Allows high frequency harmonics to pass through but filters out lower frequency harmonics below the cutoff frequency: As you can see, the fundamental and second harmonic are filtered out (and the third is attenuated) which will result in a very thin sound.
  • Page 12 (which we will look at later) although you can hear the effect when setting these filters’ FREQUENCY control. Although these filters won’t allow Fusion to ‘talk’ (!!), they do have a curious, eerie vocal quality that can be quite endearing in certain circumstances and with certain sounds.
  • Page 13 ‘model’ or recreate the irregularities present in the analog circuitry of these filters and thus recreate the character of the original. Fusion currently includes a filter modelled on the one found in one of the classic semi-modular synths of the early 70s.
  • Page 14 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Using filters - Cutoff Frequency Regardless of their type, all filters pretty much work the same way. There is a CUTOFF FREQUENCY control that sets the point at which the filter starts attenuating: When that cutoff frequency is moved by turning the CUTOFF FREQUENCY control, you will hear the tone of the sound changing.
  • Page 15 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Of course, similar things happen with other filter types - for example, a highpass filter: With a bandpass filter, the ‘band’ becomes narrower with higher resonance settings thus emphasising the harmonics in the area of the cutoff frequency: Resonance is an intrinsic component of many analog synthesiser sounds.

  • Page 16: Ring Modulator

    ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Recent advances in DSP technology means that almost any roll-off can be defined and we can have anything from 1-pole (6dB/Octave) to 8-pole (48dB/Octave): And if you are wondering what the dB/Octave refers to..it’s the amount of attenuation of level per octave.
  • Page 17 And of course, you’re not restricted to ring modulating vocals - try drums or guitar... whatever! Fusion allows external audio inputs to be ring modulated in this way - simply select EXT IN as one of the oscillator’s ‘waveforms’ and presto!!! Granted, the ring modulator is perhaps not the first module to reach for to create ‘mainstream’...
  • Page 18 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Amplifier Strictly speaking, the amplifier in the audio chain of an analog synth is not really a ‘processor’ as such other than it allows you to control level, typically at the end of the signal chain before the signal reaches the outside world.
  • Page 19 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL CONTROLLERS Before we look at the various controllers, we are going to take a trip back in time to take a basic lesson in ‘voltage control’ because with an understanding of how synths used to work, we can better understand how controllers work in a modern environment.
  • Page 20 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL With this ‘rule’, it becomes considerably easier to control sounds. For example, if we have a keyboard that generates 1 volt for every octave, we can ‘play’ the pitch of the oscillators musically And what do you think would happen if we had a device that generated a slowly rising and falling voltage that was applied to pitch (i.e.

  • Page 21: Envelope Generator

    ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Now... what happens if we apply this to filter cutoff: That’s right - the cutoff frequency will rise and fall (or ‘open’ and ‘close’) slowly. In other words, the sound will get brighter and then mellower as the voltage rises and falls.
  • Page 22 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL However, we can also apply an envelope to filter cutoff - in this way we can vary a sound’s tone over time during the course of a note. For example, you will remember that when we looked at...
  • Page 23 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL We can also apply these varying voltages to pan position: Centre Right Centre Left Centre Centre Right Centre Left Centre Right Centre Left But what of other controllers? Well, given that we now know the basic rule about how voltage can control pitch, timbre, amplitude, waveshape and panning (and other things as we shall see), we can devise other controllers.

  • Page 24: Envelope Generators

    ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Envelope generators Also known as envelope shapers or (on Moog synths) contour generators, the purpose of the envelope generator is to generate a programmable control shape every time a trigger is received: ENVELOPE GENERATOR TIME...
  • Page 25 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Every sound has an envelope. A piano, for example, has a fast attack and a long decay: TIME A guitar or harp or bass guitar has a similar envelope. A plucked (pizzicato) violin has a similar...
  • Page 26 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL However, strings (ensemble or solo) rarely sustain at full level and tend to swell and then fade slowly to a sustain: TIME Woodwind tends to have an initial attack that is soft but has an initial ‘burst’ that settles down...
  • Page 27 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Attack Decay Sustain Release TIME Note-On Note-Off The Attack, Decay, Sustain, Release phases are often abbreviated to ADSR. When applied to an amplifier, we can see how it works: The constant level output from the oscillators/filter is fed to the final amplifier, the output of which is controlled exclusively by its envelope generator.
  • Page 28 However, whilst the basic principles still apply, a modern VA synth such as Fusion can offer so much more such as velocity (and other external) control of envelope times but to discuss those here might only serve to confuse the issue.

  • Page 29: Low Frequency Oscillators (Lfos)

    As such, LFOs are simple to understand - just looking at the waveshape allows you to predict the effect it will have (and fortunately, unlike some other synths, Fusion displays the waveshape graphically so you can predict at a glance what effect the LFO will have!).

  • Page 30: Low Frequency Oscillator

    ALESIS FUSION ANALOG SYNTHESIS TUTORIAL The LFO as a ‘module’ is very simple and looks a little like this: Rate LOW FREQUENCY Select OSCILLATOR Typically, it offers a triangle wave, rising and falling sawtooth waves and a square wave which can be selected with a switch.
  • Page 31 - if you wanted a slow filter sweep, you had to forego vibrato; if you wanted vibrato, you had to forego slow filter sweeps. Fusion can have up to six (!!) LFOs and, as a result, many things are possible. For example, one LFO...

  • Page 32: Sample & Hold

    A few synths allow the ‘shape’ or symmetry of the LFO’s waveforms to be altered as well for even more control flexibility. Fusion allows all of these and more but that’s probably enough to be going on with for now!!! Sample & Hold This is another old module from the early days and it falls somewhere between being a controller and a control processor.
  • Page 33 ‘standard’ S&H random effects was/is ultimately limiting if you want to step beyond that and be more experimental. Fusion proudly re-instates the original implementation of the S&H unit to allow some serious creative sound design that extends way beyond the realm of all synths other than traditional analog modulars.
  • Page 34 However, the modwheel can also be used to open and close the filter or change pulse width or control oscillator sync sweep - whatever. Most synths (including Fusion) allow this controller to be totally assignable to almost anything you want.
  • Page 35 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL Controllers - conclusion Understanding the way the various controllers affect pitch / tone / amplitude is crucial to getting the most out of your synth. There are no hard and fast rules and so it is difficult to be specific but hopefully the explanations of the various controllers can give you some clue as to the power that is latent within your synth to create a broad range of sounds.
  • Page 36 ALESIS FUSION ANALOG SYNTHESIS TUTORIAL VA SYNTH TUTORIAL - CONCLUSION Hopefully, this tutorial will have given you a deeper insight into the workings of your synth. Apologies if it has been a bit technical at times but it’s only with a thorough understanding of the basic principles that you can begin to explore and understand the depths of your synth.

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