Organ Tone Wheel development.

I think it can be done by running 11 ramp type oscillators simultaneously. They need to be the top octave of the organ keys. Next, you can tap onto these ramps and do two things. First, rig something up that locks on to the ramps current value but has it's own reset. So for example say a note an octave down from high C was played and high C was the highest frequency of all 11 ramps. When the octave down note is played, initialize it's ramp with the current value of high C's ramp. Then let it clock up in tandem with C2 but let it continue to clock twice as long as C3. So now we have a ramp that is an octave down from C3 but has twice the amplitude. Next divide the amplitude by 2 and use the ramp in place of the ramp in the ramp to sine converter. I think you'll get a phase coherent octave down sine wave. Of course playing a note 2 octaves down will need to be 4 times as long and divided by 4 to get a note 2 octaves down. So that takes care of the phase problems with a polyphonic synth where the sine start at zero when the note is played. You also need to fade the note in to minimize the click because it doesn't start at 0. Once you have the ability to generate the ramp of the fundamental that is phase locked with one of the 11 master ramps you're good to go. This ramp can be multiplied by 2 or 3 or whatever to generate sinewaves that have their volume adjusted by the drawbars. Basically whenever a single note is played it is first phase locked with one of the 11 master continuously running oscillators, next it is divided down by the number of octaves it is below the masters and then scaled by dividing by the same number. Then this new ramp also generates 8 other ramps that are the frequency ratios of the 8 drawbars. Like 2, 4, 2 and 2/3 etc. Since there is a sub oscillator which I think is labeled 16 in might be best to generate a ramp for each note that is another octave down for starters. Then make the other 7. I think they are just time 2,3,4,5,6,7 or something like that in reality by end up being label as 16, 8, 4, 2 and two thirds and so on. I can't think of any other way to do it. I don't see one long ramp like your talking about yet. If anything it might be one continuous clock, which it is. Please elaborate…

I see what you're doing.

I don't know it the modulo's create exact frequencies though. Are they a little bit off?

This may be a good way to generate the draw bar tones but the ramp will eventually reach it's max. Maybe start out with 11 equal tempered ramps of the lowest notes or highest notes ever played and connect those ramps to these modules for the draw bars. That'll mitigate the forever increasing ramp.

Perhaps use the ramps of the highest notes played and create a sub oscillator from the note played that stays in sync with the master oscillator. Or the other way around and start out with the lowest notes running the master oscillators. That might be better because there's better resolution to start out with.

I read an article and found something out I didn't know, some organs actually had 12 bars. One for each note and a dummy for balance of some sort. I guess that's why we need 11 master ramps. One for each note. Seems like the modulo's would still act like independent ramps even if they don't start at 0. But that's ok because the note on and off need attack and release time. So the offset won't be so bad. Also it might work out better if the low notes have longer attack and release times than the higher notes.

Yeah, they are perfectly in sync. So far so good. Too bad the ramp can't reset. It can but the length has to be divided equally by all tones multiplied by each other. That's a big number.

Hey Colin, check this out. Your solution is perfect. I had no idea a 64bit ramp will continue for 266,879,977,918.25161481481481481481 hours at 192k sample rate. Holy cow, did I do the math wrong or something. If that's right, your solution is perfect. There is something else that needs to be done with a tone wheel though. Organs have something called foldback that prevents tones from getting too deep or too high. We talk about that once before but to refresh your memory they basically crossfade descending tones into below around 30 hz or so into the octave high. They also do the same for high tones except the crossfade climbing notes in notes playing an octave down. The modulo might work for that but I'm not sure how to do it. Basically any drawbar needs to start repeating the same octave over and over when the tones are too high of too low. Generally the fundamental tone of an organ is not the problem, it's the drawbar that cause the problem. Those good organs managed to pull that off with the teeth. I think it ends up sounding better than simple filtering. Otherwise I see no reason to do it. I found the info a while back on how it was done. If I remember, they had it down to a fine art. Every draw bar was customized to start the foldback process at a certain tone.

Can the modulo's be set to turn over if the ramp is going down? The modulo's only need to start working above or below a certain threshold of the drawbar tones. I don't think it's necessary for the actual pitch of the key pressed, just the drawbars. The 16 foot bar is the problem going down and the others are the problem going up.

That makes sense, I was thinking they may have tried to fatten up the upper registers by folding back the overtones that are way up there above the 3-4k, the high tones produced by the drawbars. I guess that's possible but maybe it was a case of making the most with what teeth they had to work with. I'm kinda leaning towards the lookup table suggestion because I found a list of what they actually used for each note and where each drawbar started its foldback. The tables could easily be made with excel and it should be easy on the cpu because each table will only be addressed when a note is played and it's event based. Probably have two tables, another for relative volume for each tone. That might equate to what they did for the most part. The click is easy and the percussion could be done with fm. I think they had a choice of either a third harmonic or second harmonic percussive tone that was only kicked in on the first note played and anytime after all keys have been released.

Anyway, that was pretty good thinking using a single ramp with the modulo's. That might actually come in handy for a lot of things. I guess it works because all ramps initialize at start up. You don't really have to have the overtones for the draw bars if you're making a synth of some sort and it might fix up an everyday subtractive synth too. It is kind of irritating when your playing octaves on low bass notes and the timbre changes depending on your timing. Ya man, that's pretty swift, I guess the only drawback is the need to fade in the note. Without a fade in you'll get a click if it doesn't start at zero. That's what I though the click was on the organ but they may have produced a click by another means so all notes would have the same click volume or at least sound like they do. This is pretty good, it has a section of fold back.https://electricdruid.net/technical-aspects-of-the-hammond-organ/#:~:text=Harmonic%20foldback%20is%20used%20to%20reduce,tonewheels%20%281-91%29%20used%20for%20each%20harmonic.&text=Harmonic%20foldback%20is%20used,used%20for%20each%20harmonic.&text=is%20used%20to%20reduce,tonewheels%20%281-91%29%20used%20for