Yamaha GS1-inspired synth, revisited.

[tulamide]

We are basically seeing it the same way, but I also discovered where we thought differently. See below.

It says that single notes are always detuned by the same amount, which leads me to ask “why?” A single note has nothing to beat against.

Here you come to an abvious conclusion. However, my brain went "detuned, single note? oh, it's detuning of (two or more) oscillators!"
That would make detuning for single notes meaningful.

Then it says that detuning is determined by the order in which notes played in a “group” (chords) will be detuned according to the order in which they were depressed. This leads me to think that the detuning is actually done by a lookup table which has pre-made “random” entries.

Yes, but nowadays you don't need a lookup table either. You just use seeded random. Everytime you give it seed "x", the random generator will spit out the exact same series of numbers. Just like LUTs, but simpler.

However, while I think it would be noticable if the same note would have randomized offsets to the fixed detuning, this won't be the case with a LUT/seeded random. So it doesn't make a serious or noticable difference (unless the random offset is like a halftone or something like that)

[Spogg]

It says that single notes are always detuned by the same amount, which leads me to ask “why?” A single note has nothing to beat against.

Here you come to an abvious conclusion. However, my brain went "detuned, single note? oh, it's detuning of (two or more) oscillators!"
That would make detuning for single notes meaningful.

You make a very good point that I hadn’t considered. A sound would be made from several operators and they could be detuned against each other. However, the detuning of oscillators within an FM algorithm would have different results depending on the chosen algorithm and its settings, so I suspect it applies to the base pitch rather than individual oscillators that make up a sound.

Then it says that detuning is determined by the order in which notes played in a “group” (chords) will be detuned according to the order in which they were depressed. This leads me to think that the detuning is actually done by a lookup table which has pre-made “random” entries.

Yes, but nowadays you don't need a lookup table either. You just use seeded random. Everytime you give it seed "x", the random generator will spit out the exact same series of numbers. Just like LUTs, but simpler.

However, while I think it would be noticable if the same note would have randomized offsets to the fixed detuning, this won't be the case with a LUT/seeded random. So it doesn't make a serious or noticable difference (unless the random offset is like a halftone or something like that)

We don’t know the method Yamaha used to generate the random values of course, but I feel sure that it’s not done on the fly, while playing. It would be interesting to see if the exact same random detuning happened every time you turned the instrument on, so if you buy me a nice working GS-1 I’ll check it out.

[k brown]

I think I like this better -

I've never really enjoyed building waveforms with additive oscillators, but I'm very much intrigued with the core concept of the Synclavier's FM engine: two-op FM with the carrier capable being a sine or more complex shapes.

So, this version has Martin's WaveShape oscs for the carriers in place of the additive, and for good measure, the modulators are now Martin's Spread Partials oscs. Since both can generate pure sine, it can still be used in original GS1 fashion.

It's Vicanek squared! (I've given him credit on the front panel).

I've included a button in the carriers to direct the modulators directly to the audio out, so one can have a great deal of 'FM' colors to play with without doing any actual FM programming.

Most of the presets are carried over from SkematicGS (sine on modulators and carriers), but they sound a little different because this one has no feedback. Having all those waveform options in both the modulators and carriers makes it a little less neccessary. It's interesting to hear the changes in the sine-only presets by moving modulator and/or carrier off from sine.

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[k brown]

To retain the full compliment of feedback, and the GS1's Modulator cross-mods, this version keeps the Modulators sine, but still has the WaveShape oscillators in the Carriers instead of additive ones.

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This probably the best of both worlds?

[k brown]

A better best.

Reading about Tone2's Nemesis (Lord I'm sick of everything in the non-Classical music world having to have ugly/dangerous/painful/evil names, that most of the time don't even make sense in the context - what would 'Nemesis' possibly be a "nemesis" for/to?) "Neo FM" engine, I had to give a nod the great ideas therein.

So, the controls to change the Carriers' waves from sine to complex have been changed to incorporate some of the main 'Neo FM' functions. Rather than crossfade Saw > Pulse, with a seperate Timbre control, one knobs morphs sine-to-saw turned CCW, and sine-to-square turned CW (this roughly approximates the Neo FM 'filters'). The resulting timbre can be modulated by the carrier's EG. A Mix control that crossfades between the timbre created by the FM from the Modulator to the un-modulated wave created by the Carrier's Saw-SIne-Squ control (this turns out to be more useful than it might seem at first). A Phase control than shifts the phase between the modulator and the carrier (I'd done this in my Buchla emulations, but had forgotten how useful it is in fattening some FM sounds). And lastly a sine mixer that mixes in an un-modulted sine wave at the pitch of either the Carrier or the Modulator (especially useful when the Carrier is at significantly higher frequency than the Modulator, which sounds like a high pass filter).

These controls provide for a wider and more useful range of Carrier waveforms than what I'd originally done, while still utilizing Martin's wonderful WaveShape oscillators.

I'm starting on a piece that will include most of the 'Neo FM' features (complex oscs for modulator and carrier, full synth controls, a mod matrix, etc,). Using the GUI style I used for my version of the Trautonium-inspired projects that Spogg and I collaborated on (he did all hard stuff ) His is called 'Trout', and is a way more complex and complete Trautonium emulation: viewtopic.php?f=3&t=58028&p=170078&hilit=Trout#p170078

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[Spogg]

Lovely to see you working with FS again!

I like to try your stuff when you indicate that it’s finished (and with some presets). Of course I’m very keen to help with any technical issues while you’re still developing a product. So if I don’t test and comment it’s not because I’m ignoring you and your excellent work; I’m just in a wait state!

[k brown]

Fair enough . . .

I think you can consider the latest version the finished one, I like it the best. Has quite a few presets, too (for me, anyway ).

[Spogg]

This is a great synth.
I must say your set of presets is really good, which is what I auditioned to form my opinion.

One thing I missed is an INIT preset, but you have so many different sounds I could start from any of them.

Very well done (again!).

[k brown]

Thought I put an INIT at the end (128), but if not I'll do that.

Anyway, thanks for checking it out, and the help with Detune, my original shot at it was pretty useless.

Since the GS1 was not user-adjustable, synthesis-wise, but purely performance oriented, I should probably add some more 'bread-and-butter' presets; classic DX7 stuff like EP, bass and the like.

[Spogg]

Thought I put an INIT at the end (128), but if not I'll do that.

Oh dear! I missed that.