FM Synthesisers and the Yamaha FS1R
Formant Synthesis rack module...
The DX7 was just one model in a whole family of synths created by Yamaha during the early eighties but it was arguably the most popular model with it's little brother, the DX9 lagging a long way behind in the popularity stakes, and it's big brother, the DX1, costing more moolah than the average pocket could comfortably carry!!!
The system that the DX series uses to create it's sound colours is known as FM, or Frequency Modulation, synthesis. Basically the hardware comprises a number of Operators - these are tone generators in much the same way as the oscillators in an analogue synth, complete with a voltage controlled output amplifier tacked on the end to modify the amplitude against time of the oscillator's output. Infact, connect up the Operators of a DX synth in a certain fashion and they produce very basic sounds indeed. The clever bit is the way Yamaha designed the system so that the Operators can be configured into any one of 32 different interconnection patterns, some in parallel with each other, some with their output feeding the input of the next Operator. These interconnections are referred to as Algorithms. Whenever the output of one Operator modulates the input of the next a shift in output frequency of the modulated Operator occurs in direct proportion to the amplitude of the modulating source. By very careful tweaking of levels and associated time parameters, sounds of a most complicated nature, including very close approximations to "real" instruments can be synthesised. Bells and other clangorous tones are a breeze with this synth but new and quite unique timbres can also be created. Ever hear a good DX7 Hammond organ complete with key click? Or the harpsichord complete with the sound of the quill as it plucks the string? If not take a second out to listen to these sound bytes and you should see just what I mean...
The down side to this instrument is it's difficulty to program by virtue of it's multi level menu system, an ill omen of things to come in later synths built around this time... tweakability seemed to die in the eighties. Not withstanding, the Yamaha DX7 is an industry standard and has changed little through the years even when it appeared in it's second incarnation as the DX7 Mk. II. A most powerful little machine with 16 voice polyphony, the one we had from new until very recently boasted the DX MAX retro fit hardware allowing layering of sounds, pseudo delay effects, detunes and a comprehensive arppegiator into the bargain.
The DX series synths have not been available new for quite a long time but their legacy lives on in some modern keyboards and computer sound cards which still utilise FM synthesis. There are many web sites devoted to sounds for this synth and it is still possible to pick up a DX7 in good condition for reasonable money. If you fancy parting with a few of your hard earned readies try persusing the Sound On Sound classifieds.
And now, what about the FS1R?
In short, what we said about the DX series voice creation system applies pretty much to the FS1R too... with exceptions, or rather with clever additions - indeed, the FS1R will happily run DX7 patches along side it's own more complex patches and ours does just that. Recently we took the DX7 out of our keyboard rig to make way for a Roland JX10P - the patches we used on the DX are now played on the FS1R instead. Indeed they have crossed instrument platforms with very little need for extra tweaking despite being layered sounds on the DX7's Max hardware.
So... 8 operators on board, operators with the same architecture as the DX series except that instead of offering just a sinusoidal output waveform they can offer any one of seven different waveforms, or "spectral forms" in FS1R parlance. This factor alone creates the scope for a far greater sonic pallette. Next we have a total of 88 operator interconnect algorithms compared to the DX7's 32. Now take into account the fact that we may combine algorithms, up to 4 per FS1R voice, and then up to 4 voices may be combined in a Performance - well perhaps you can see that now we are shifting into really quite complex sonic territory!
And for good measure lets tack on the filter section of Yamaha's AN1X virtual analogue downstream of the FM voice creation circuitry - incidentally, the DX series never had a filter - now we can sweep, resonate, band pass, band limit etc. etc. etc. to our heart's content...
So is that it? Not quite...
Our 8 conventional operators are accompanied by a further 8 operators sporting the additional title "Voiced". What this is all about is the ability for the second set of 8 operators to create formants. Don't panic because this is not as hard to understand as the name might at first suggest. Basically a formant operator mimics the actions of the human larynx allowing the production of vowel sounds by clever use of fixed filters connected in series or parallel. By the addition of noise generators used in conjunction with the same formants consanants can also be created. So in essence this little 1 U rack can actually talk! And it does... but it's not just in synthesis of the human vocal tract that formants come into their own. Careful use on more conventional sounds will increase their realism dramatically because it's not just synthesis of the human voice that benefits from formant filters - conventional instruments exhibit formant filtered characteristics in their timbres too.
So... there we have it. An amazing synthesiser. But it does have one rather dramatic downside, it's programming system. Yamaha have long been exponents of the multi level editing page concept and personally I find it a real b*ll ache! What could have been the near perfect instrument is hampered incredibly by the fact that you have to go through endless button presses and layers of menu to find the parameter you want to tweak. This can lead to extreme frustration as you totally lose track of where you are... in short it is far from user friendly.
Take a listen to these amazing sound bytes and I think you will quickly realise just why we have an FS1R in our kit now...