Multiple pitches from Rocktave?

[R.G.]

OK, next iteration. One 16F??? controller and four 82D54 peripheral timers. The 82C54s have three 16 bit timers that can be set to run in square wave output mode, and clocked at 8/10/12MHz. That should get you three notes, so you need four of them. The PIC programs the timers, then goes to sleep.

[Lurco]

discrete TOG!?!

[David]

discrete TOG!?!

I'm picturing a box about the size of a Marshall half-stack...   

[David]

OK, next iteration. One 16F??? controller and four 82D54 peripheral timers. The 82C54s have three 16 bit timers that can be set to run in square wave output mode, and clocked at 8/10/12MHz. That should get you three notes, so you need four of them. The PIC programs the timers, then goes to sleep.

This bears further cogitation, Sensei...  Domo arigato!   

[Taylor]

You know, every time I think I'm beginning to understand enough about electronics for my own needs, I ask a question like this, and each answer is more over my head than the last. I have a lot of reading to do.

I will say this, on a subject with which I am more comfortable. I think a discrepancy of 2 cents is not noticeable to most people, even most musicians. Further, we are all using 12 tone equal temperament, which is itself false by much more than 2 cents in most intervals - up to about 17 cents off for some intervals.

In addition, the harmonics of a real note are not all "in tune" with the note. The 11th harmonic is a whole quartertone away from any equally tempered  note. So, if we are using this pitch divider to shape the harmonics of a note, as in a drawbar organ, I think it's totally ok for the shifted pitches to be inaccurate, since they would actually be inaccurate as harmonics if they were "perfectly" tuned to the original note.

Now, if I could understand your approach which creates a 2-cent falsity, I might very well try it.  

[David]

How far did you follow the discussion, Taylor?  The questions were specific and were asked for your benefit as well as mine.

[soggybag]

I will say this, on a subject with which I am more comfortable. I think a discrepancy of 2 cents is not noticeable to most people, even most musicians. Further, we are all using 12 tone equal temperament, which is itself false by much more than 2 cents in most intervals - up to about 17 cents off for some intervals.

I think Rock Music tolerates a wider tolerance range. It's often called style, feeling, the blues, genius etc.

[Mark Hammer]

The importance of 2 cents difference in pitch will depend on how you use such a device.  If there is any intent to generate more than one parallel note at a time, or harmonize with another instrument, that 2 cents may be aggravating.  On the other hand if one is simply soloing over a bass/drums rhythm section and its one parallel note, big deal, right?

[Taylor]

How far did you follow the discussion, Taylor?  The questions were specific and were asked for your benefit as well as mine.

Oh, I' ve read everything here several times now. I started feeling in over my head upon R.G.'s reply #17. I know the topic of various permutations of pitch-shifting is something people have been working on for decades now, so it's no surprise that people have gotten deeper into the problem than I ever have.

I'm thinking that, for my own purposes, the Harmony Generator is going to be a useful starting point. I'm not necessarily looking for all 12 tones of 12TET simultaneously, but rather something more like a schizo version of the EHX HOG. (By which I do NOT mean polyphonic tracking, don't worry; I'm not that egotistical!)

[Taylor]

The importance of 2 cents difference in pitch will depend on how you use such a device.  If there is any intent to generate more than one parallel note at a time, or harmonize with another instrument, that 2 cents may be aggravating.  On the other hand if one is simply soloing over a bass/drums rhythm section and its one parallel note, big deal, right?

Yeah, it's certainly a grey area. For instance, a guitar string typically goes more than 2 cents sharp in the attack stage of the note, just as a result of you plucking it. As far as harmonizing, I maintain that most people could never hear a falsity of 2 cents. The problem really is only significant, IMO, when 2 instruments play the same note simultaneously, in the same octave - in this case, 2 cents will create an obvious beating.

Even the intonation guru himself, Harry Partch, wrote that 2 cents can't be heard except in the case I described above.

[Taylor]

In addition, the harmonics of a real note are not all "in tune" with the note. The 11th harmonic is a whole quartertone away from any equally tempered  note.

In fact, to expand on this in a way that relates to octave dividers, in metal strings (as in pianos, guitars, basses...) the harmonics are slightly inharmonic. Read up on stretched piano tuning: most pianos are tuned so that each "octave" is actually slightly sharp, because the 2nd harmonic of these strings (which in theory should be equal to twice the frequency, or 1 octave higher) is slightly sharper than that. In order for, say, C5 to be in tune with the second harmonic of C4, C5 needs to be a few cents sharper than "perfect". How much is a matter of some debate, but it seems that some say around 35 cents over the course of the whole piano, which is about 4 cents per octave.

So, it would actually sound more in tune to have octaves 2 cents sharp than not.

[R.G.]

OK, next iteration. One 16F??? controller and four 82D54 peripheral timers. The 82C54s have three 16 bit timers that can be set to run in square wave output mode, and clocked at 8/10/12MHz. That should get you three notes, so you need four of them. The PIC programs the timers, then goes to sleep.

This bears further cogitation, Sensei...  Domo arigato!   

Hai, dozo.

[David]

I don't mean to derail the train here (especially since I feel I helped lay some of the track  ), but in the midst of all this thought regarding what could be considered a digital replacement for a TOG, maybe we should step back and look at the forest for a minute.  OK,  TOGs went to dinosaurland, right?  But synths are still being made, bought, sold and used all over the place.  To my mind, this begs the questions:   How is tone generation being done without a TOG?  Why can't we obtain and circuit-bend this device to our purposes?

[R.G.]

I think a discrepancy of 2 cents is not noticeable to most people, even most musicians. Further, we are all using 12 tone equal temperament, which is itself false by much more than 2 cents in most intervals - up to about 17 cents off for some intervals.
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Yeah, it's certainly a grey area. For instance, a guitar string typically goes more than 2 cents sharp in the attack stage of the note, just as a result of you plucking it. As far as harmonizing, I maintain that most people could never hear a flasity of 2 cents. The problem really is only significant, IMO, when 2 instruments play the same note simultaneously, in the same octave - in this case, 2 cents will create an obvious beating.

Even the intonation guru himself, Harry Partch, wrote that 2 cents can't be heard except in the case I described above.
--------------
In fact, to expand on this in a way that relates to octave dividers, in metal strings (as in pianos, guitars, basses...) the harmonics are slightly inharmonic. Read up on stretched piano tuning: most pianos are tuned so that each "octave" is actually slightly sharp, because the 2nd harmonic of these strings (which in theory should be equal to twice the frequency, or 1 octave higher) is slightly sharper than that. In order for, say, C5 to be in tune with the second harmonic of C4, C5 needs to be a few cents sharper than "perfect". How much is a matter of some debate, but it seems that some say around 35 cents over the course of the whole piano, which is about 4 cents per octave.

So, it would actually sound more in tune to have octaves 2 cents sharp than not.

I reserve the right to be wrong...  

I was quoting from my mental storehouse of numbers and after reading your note went back and read more from actual books. You are correct. There are at least three thresholds of pitch perception quoted in stuff I have at hand; the central value seems to be 5-6 cents for most people, whatever "most people" means in that reference. Musicians tend to be better, and some people can't distinguish half a semitone very well.

So sure, get down to 2 cents and we have something. More on this later.

[Taylor]

I reserve the right to be wrong...  

Whoa... this is a scary thing to be hearing from R.G.

I think it's tough to really say any of this with mathematical certainty anyway - it's almost like trying to figure out how asymmetrical a face can be before it's ugly. 

[R.G.]

I don't mean to derail the train here (especially since I feel I helped lay some of the track  ), but in the midst of all this thought regarding what could be considered a digital replacement for a TOG, maybe we should step back and look at the forest for a minute.  OK,  TOGs went to dinosaurland, right?  But synths are still being made, bought, sold and used all over the place.  To my mind, this begs the questions:   How is tone generation being done without a TOG?  Why can't we obtain and circuit-bend this device to our purposes?

Synths generally don't use TOGs. Organs were the big users of TOGs and I understand that many older organs, made in the 70s and 80s have the MK50240 and its cousin the 50250 in them. A TOG and 12 CD4024 seven stage dividers generate all 96 of the musical notes.

I think organs are into ASICS these days, but I don't really know.

Synths generally use high-accuracy voltage controlled oscillators with 1V/octave sensitivity. Digital synths I don't know.

I think your running down what does the job these days is a great idea.  

As for the bigger question, why not get some other circuit which does the job and just abuse it to do what we want, pretty much if it takes in an oscillator and puts out all of the frequencies of the musical scale, it's a top octave generator, I think.

[R.G.]

I reserve the right to be wrong...  

Whoa... this is a scary thing to be hearing from R.G.
I think it's tough to really say any of this with mathematical certainty anyway - it's almost like trying to figure out how asymmetrical a face can be before it's ugly. 

Now, ugly I can deal with.

[puretube]

discrete TOG!?!

I'm picturing a box about the size of a Marshall half-stack...   

well, ehh, ...

[Taylor]

The harmony generator generates one note at a time, largely because its divider cannot simultaneously generate all those divisor ratios in the proper proportions.

So I am looking over the harmony generator schematic, and to me, it looks like IC8 puts out a unison note, as well as the same note in 6 other octaves. In the schem, there is a switch to select which octave you want, but why couldn't there be a little mixer so we could have any of those octaves we want, with controllable volume?

It seems I could get quite a few pitches using only 3 harmony generators, (unison x 7 octaves, third x 7 octaves, fifth x 7 = 21 glitchy frequencies...!). Am I wrong here?

[David]

I think your running down what does the job these days is a great idea.  

I have my assignment.