emm harmony synthesizer analog project

[pinkjimiphoton]

just found this... looks like it could be interesting... at least to me <probably old news, but still....just when ya think ya seen it all>

http://www.muzines.co.uk/articles/harmony-generator/3574







meant for keyboard use but i bet some genius guitar player could adapt it to be useful by the rest of us.
more info at the link.

if anybody burns some of these, please let me know, i would love to mess with one. thanks!

[ElectricDruid]

Probably "meant for keyboard use" because synths and other keyboards give a much steadier pitch and volume level over the course of a note than guitar. Note tracking for a basic monosynth is a lot less difficult that it is for guitar.
I'm not saying it won't work...just that you should adjust your expectations accordingly!

T.

[Marcos - Munky]

Mark Hammer have the full article at his page. I think he built it, but didn't got it to work. At least, I remember reading somebody here built it but didn't got it to work.

[Mark Hammer]

Yeah, Munkyis right, although I have to give RG credit for sending me a copy of the article in the first place.

Mine is sitting on the stack of populated boards that don't work well enough (or at all) to be boxed up.  I have to go over it with a magnifying glass and verify that the traces are all where they should be and not where they shouldn't.  That will be followed by some signal tracing, and maybe some scope-work.  I'm eager to get it working.

[pinkjimiphoton]

just goes to show ya there's nothing new out there lol...

wonder if it would be worth hacking into my old roland gr-1?

too much like work. i'll wait for mark to see if it actually does anything. i have a pretty big popcorn supply.

but i bet there's tricks that would help, like running a hyper saturated fuzzed guitar into it. but to me, that makes anything sound good.

[Mark Hammer]

Just tweak IC1, Jim.  Stick some diodes in the feedback loop, increase the gain, cut the treble with a feedback cap to trim the harmonic content and leave mostly fundamental.

[pinkjimiphoton]

mark, thanks bro, but i got like, sooooooooo many things ahead of this

that said... i assume you've seen this?

http://www.muzines.co.uk/articles/circuit-maker/4310



Harmony Generator Extension


Paul Williams

The Harmony Generator published in E&MM October 1981, although very useful, is only capable of generating square waves. Also, only one octave output is available at a time. The circuit shown in Figure 1 not only provides the Harmony Generator with triangular and sine waveforms on a selected octave output, but also provides facilities for mixing these and all seven octave outputs simultaneously.

The additional waveforms are produced by a voltage controlled function generator, IC 11, which is used in a phase locked loop (PLL) in conjunction with IC10. The PLL IC10 is used only for its phase comparison and error voltage generation functions, its internal VCO not being used. Instead, IC10 controls the frequency of oscillation of IC11 by a control voltage applied to pin 8 via an inverting and level shifting stage, TR2. The CV is adjusted such that the loop frequency is the same as the input frequency presented to pin 14 of IC10. IC10 and IC11 thus constitute a square wave to sine wave (and triangular wave) converter.

Since waveforms other than square waves are involved in the mixing, the envelope shaping must be linear rather than by means of the very elegant chopper system used in the original Harmony Generator design. An operational transconductance amplifier, IC12, is used both as a virtual earth mixer and a current controlled amplifier to perform the envelope shaping function. The mix is set up on RV4-12 and summed to the virtual earth node at IC12 pin 3 by R31-39. The rectified input voltage from IC2 in the Harmony Generator is converted into a control current for IC12 by TR3 operating in the common base mode. The final output mix between direct and harmony signals is affected by RV13 which is in a rather odd configuration best suited to the current output of IC12.

This circuit is not suitable for operation on the original +9V battery derived supply, so a +12V mains operated supply is shown. The duty cycle of the square wave, which should be monitored at IC11 pin 9 is adjusted by RV3. The 50% duty cycle setting can be clearly detected by ear since its harmonic structure is quite markedly different from any other duty cycle setting. After the duty cycle has been trimmed, the sine wave output will be of reasonably low distortion. However, if very low distortion is required then R29 can be replaced by a 100k preset which is adjusted for minimum sine wave THD.

Although it would add considerable complexity, there is no reason why the circuitry of IC10 and IC11 should not be duplicated for all octave outputs, allowing sine and triangular waveforms to be produced on all seven octave outputs simultaneously.

[stringsthings]

These guys will sell you a PCB:

https://www.circuitbenders.co.uk/forsale/harmonic/harmonic.html

[garcho]

just goes to show ya there's nothing new out there lol...

i don't know, some of those TC Elec pedals are blowing me away, the "toneprint" thing is amazing. and eventually maybe we'll have that eventide transient-splitter thing in pedal form, that would be cool. jus' sayin'

OT sorry

[pinkjimiphoton]

no worries gary, i am the king of OT.

the toneprint thing is cool, but i do NOT like tc electronic. i won a pair of them signed by steve morse a few years back on farcebook, a polytune, and a nova delay. the polytune put out all kinds of RFI in use that my amp would pick up,
and the nova delay crapped out on me live on stage and had to be sent to canada for waranty. when it crapped out the same way 3 months later, they said i was on my own. luckily, i had paid attention on the phone and heard them say all they did was re-seat the memory chip. so i did it myself, problem solved... but still not impressed. i traded both off for some other stuff.

i DID work on one of their parametric eq's and brought it back from the shades with a complete recap and a couple resistors that had drifted way off whic was an amazing pedal.. but there was a huge diff between hand made tc electronic stuff and cheap ass chinese made tc electronicS stuff imho

[pinkjimiphoton]

These guys will sell you a PCB:

https://www.circuitbenders.co.uk/forsale/harmonic/harmonic.html

oh, poo. so much for my excuses!! thanks bro, i am mos def gonna get on this. i'm betting if i can't use it for me, my keyboardist will love it.

thanks you!

[pinkjimiphoton]

i pulled the trigger on the board, i'll let ya know how it works out.
figuring some very compressed fuzz before it may help the tracking issues, or it may just be a noise maker, too.

we'll see.

[Mr. Lime]

mark, thanks bro, but i got like, sooooooooo many things ahead of this

that said... i assume you've seen this?

http://www.muzines.co.uk/articles/circuit-maker/4310



Harmony Generator Extension


Paul Williams

The Harmony Generator published in E&MM October 1981, although very useful, is only capable of generating square waves. Also, only one octave output is available at a time. The circuit shown in Figure 1 not only provides the Harmony Generator with triangular and sine waveforms on a selected octave output, but also provides facilities for mixing these and all seven octave outputs simultaneously.

The additional waveforms are produced by a voltage controlled function generator, IC 11, which is used in a phase locked loop (PLL) in conjunction with IC10. The PLL IC10 is used only for its phase comparison and error voltage generation functions, its internal VCO not being used. Instead, IC10 controls the frequency of oscillation of IC11 by a control voltage applied to pin 8 via an inverting and level shifting stage, TR2. The CV is adjusted such that the loop frequency is the same as the input frequency presented to pin 14 of IC10. IC10 and IC11 thus constitute a square wave to sine wave (and triangular wave) converter.

Since waveforms other than square waves are involved in the mixing, the envelope shaping must be linear rather than by means of the very elegant chopper system used in the original Harmony Generator design. An operational transconductance amplifier, IC12, is used both as a virtual earth mixer and a current controlled amplifier to perform the envelope shaping function. The mix is set up on RV4-12 and summed to the virtual earth node at IC12 pin 3 by R31-39. The rectified input voltage from IC2 in the Harmony Generator is converted into a control current for IC12 by TR3 operating in the common base mode. The final output mix between direct and harmony signals is affected by RV13 which is in a rather odd configuration best suited to the current output of IC12.

This circuit is not suitable for operation on the original +9V battery derived supply, so a +12V mains operated supply is shown. The duty cycle of the square wave, which should be monitored at IC11 pin 9 is adjusted by RV3. The 50% duty cycle setting can be clearly detected by ear since its harmonic structure is quite markedly different from any other duty cycle setting. After the duty cycle has been trimmed, the sine wave output will be of reasonably low distortion. However, if very low distortion is required then R29 can be replaced by a 100k preset which is adjusted for minimum sine wave THD.

Although it would add considerable complexity, there is no reason why the circuitry of IC10 and IC11 should not be duplicated for all octave outputs, allowing sine and triangular waveforms to be produced on all seven octave outputs simultaneously.

THIS is really cool!
I built the E&MM from circuitbenders but it's really only very limited suitable for guitar. I also tried mixing the octaves with controls for each instead of the rotary switch but had no success. Has anyone tried this extension or could give me some more advice how to improve the circuit for guitar? I'm excited about the 3080 VCA instad of the chopper as I've been looking for a long time for a simple octaver/synth pedal with VCA..

[pinkjimiphoton]

i @#$%ed with this thing and @#$%ed with this thing and @#$%ed with this thing and finally threw it in the bin. gawdawful useless garbage.
couldn't get the PLL to stop whining. only ONE position of the switching actually worked, and to quote zappa, the tone was reminiscent of a farfisa organ.
it doesn't really create harmony notes, its more like the drawbars on an organ, and creates overtones.
the tracking sucked, i tried running preamps, fuzzes, distortion into it. i tried obliterating harmonic overtones with rc networks to get it to track. turn the guitar tone knobs off. no bueno at all under any circumstance.
it WORKED, cuz ya could hear the pll, gives it a semi synthi kinda double on a limited range of notes, but overall, this was one of the lamest things i ever tried to build.
i realize it was meant for synth players and all, but... if i coulda sent it back to get my money back, i would have. its THAT lame.

now i suppose others may have built it and got it to work, but its def above my paygrade, or the circuit's not up to snuff. whatever.

this one was an epic failure... i spent about a month <sometimes ocd is good> messing with it, and finally gave up.

the one ibought had a rotary switch for a mess of different octaves, as well as a switch to choose 3rds or 5ths harmony. like i said, it KINDA worked, but... not good enough for me to be able to say its even marginally cool...

at least my build wasn't.

thanks for the link, mr lime! i had not seen that before, will add it to my archive!

[anotherjim]

Don't feel bad about it Jimi. I think that's one circuit you have to build to prove to yourself how difficult it is for this concept. To be honest, it's hard enough to get working as a basic pitch follower never mind producing a harmonic. It can work in a synth, but only directly after a VCO. Try it after the filter or VCA and it will have just as much trouble.

I've often seen the suggestion of replacing the VCO in the 4046 chip with another more musical VCO. That extension circuit is the first I've seen. But it doesn't address the basic tracking issues.

The last one I built using a 4046, I just made into a noise box using every sound I could find on its pins and put it through a filter to smear out the harshest crap.
https://www.diystompboxes.com/smfforum/index.php?topic=113380.0

[Mr. Lime]

I feel with Jimi because I was disappointed as well when I plugged in for the time.

The tracking definitely has to be improved somehow. The "Into the Unknown" circuit from freppo works relatively well and tracks the single notes. Shouldn't R15 on the HM of the first post be responsible for tracking? Other circuits have controls in it's place and go up to 500k or 1M, see Jim's Demonstrator too. I have to try some other values on my HM board.
Could a ADSR help with tracking? Is there something like a suitable guitar trigger?


I agree the 3rd/5th harmonic switch is nice to have but doesn't sound very musical.
Earlier that day I tried to feed the PLL with an external LFO and sequencer which gave me some interesting pitches. I can imagine that a expression pedal works wonders like Jim used in his Demonstrator.
The extension circuit sounds too good to be true (in theory) and I would love to work with it but are +/-12V really necessary? The main circuit has only 9V applied. 


PLL circuits sure are tricky but can also give lots of options with little amount of parts..

For really useful octaves and tracking I already ordered an EH Micro Synth just for backup if my Harmonic Engine got in the bin. 


EDIT:
Not sure if this one works better but it's like a simpler version without VCA (or chopper) for the envelope but the octaves can be mixed together: http://www.bartonmusicalcircuits.com/4046/documentation.pdf
I think the extension should work with this one too.

[Ben N]

Sounds good on the drum machine demo, but that's a whole 'nother kettle of fish.

[Mr. Lime]

So what can we do for better tracking?

Does the tracking lack because of the schmitt trigger?
Does the schmitt trigger suffer from the input signal's envelope (ripple etc.)?

If yes we have to address the envelope. There are envelope detectors with lower and upper thresholds forming a gate.
Is there a chance that a clean gate signal could be much better tracked by the PLL?

Or even better a gate converted into an ADSR?


Comments please!   

[Mark Hammer]

So what can we do for better tracking?

Does the tracking lack because of the schmitt trigger?
Does the schmitt trigger suffer from the input signal's envelope (ripple etc.)?

If yes we have to address the envelope. There are envelope detectors with lower and upper thresholds forming a gate.
Is there a chance that a clean gate signal could be much better tracked by the PLL?

Or even better a gate converted into an ADSR?


Comments please!   

Assuming we're talking about the E&MM Harmony Generator, I suspect it suffers from the same weaknesses that many octave-dividers do, and that is that we are feeding them signals with far too much harmonic content and dynamic variation.  My gut says that an additional input stage that provides soft clipping and some lowpass filtering, with a teensy bit of gating, might help.  Throwing a feedback cap in parallel with the Sensitivity pot would supplement that, as would a back-to-back pair of Schottky diodes in series with the path leading to the Sensitivity stage, to crudely gate out random low-level noise.

[anotherjim]

The path for best tracking usually leads to the adaptive peak detectors in the EHX synth and Boss octave pedals.
Or you slink off guiltily into a dark corner and play with a POG!