E&MM Harmony Generator project PCB

[Andre]

In this thread : http://www.diystompboxes.com/smfforum/index.php?topic=54396.msg415703#msg415703  Mark Hammer mentions the E&MM Harmony Generator project
at his site (http://hammer.ampage.org)

If anyone wants to give this project a try, you can find a cleaned up and mirrored version of the PCB here:

http://www.xs4all.nl/~jvcn0028/files/HarmonicGenerator.pdf

If you don't do "Resize" or "Fit to page", it should print in the right dimensions.

Although I have not build one myself yet, I think the layout is OK since I did not do any rerouting.

If Mark Hammer or anyone else involved has a problem with me putting this on the web, please let me know and I will
remove it.

André

[Mark Hammer]

Andre,

Thanks so much for doing this.  As one of the few holdouts who tenaciously cling to their 56kbd modem, I always tried to keep my posted documents at a small file size, which in turn meant scanning at less than ideal resolution.  Your hard work means that more folks will be able to get past my low-res efforts and actual build this interesting and often-discussed project.

For that, you get a citizen-of-the-week prize in my books.   

Mark

[StephenGiles]

I would echo Mark's final comment. I might even have a go at this one!

[Andre]

For that, you get a citizen-of-the-week prize in my books.   

Proud citizen of the week here 

Thanks and you're very welcome Mark !

Although it was'nt really a fun thing to do, I think it was worthwile, since it is indeed an interesting project.
Now let's wait for the first build report 

André

[Andre]

Well, I did some etching, drilling and soldering and this is the result.

It looks like this:



and it sounds like this:
http://www.xs4all.nl/~jvcn0028/HarmonizerDemo.mp3

Please be warned that:
1. it's 3 minutes long
2. rather lofi
3. playing is lousy

It is only a first impression. There is still a lot of modding to be done.

(BTW) I discovered 3 minor errors on the PCB that can be fixed easily.

André

[Gripp]

Sweet!
Thanks for the clip and layout.
It doesn't seem to track that badly. I really thought it'd be worse judging from reports on pll experiments. Haven't toyed with them myself though.
Did you do the clip with the old neck pu tone down trick and straight in to effect?

Best!
Pelle

[Andre]

Did you do the clip with the old neck pu tone down trick and straight in to effect?

Exactly 

That's why the original guitar tone sounds very dull.
I think I will add a lowpassfilter and send the unfiltered input signal to the output to be mixed with the generated harmonics.

I also just found out that the first opamp clips at rather low gain, which is caused by a non symmetrical power supply.
That's why the guitar tone is rather distorted.

The negative power supply for the opamps, which is made by rectifying one of the unused outputs of the 4040, drops from -8 V to -2V as soon as I
put the opamps in their sockets. Maybe it's because I use 3 very old 741's.

André

[StephenGiles]

I wonder how much better it would sound from a guitar treared by a fundamental extractor - a lot I'd wager!

[markusw]

Cool!! 

Thanks for the report!

It doesn't seem to track that badly

I also thought it would be much worse. How much noticeable is time until PLL lock-in at the lowest notes?
Any hints on the settings in your clip?

Markus

[Andre]

How much noticeable is time until PLL lock-in at the lowest notes?

I will check tomorrow, once I fixed the clipping problem.

Any hints on the settings in your clip?

If you mean the harmonizer settings, the clip starts with 3 unison octaves down to 3 octaves up.
After that you hear 3th's 3 octaves down to 3 octaves up and finally 5th's over six octaves.

With every setting of the gain pot, there is a limited range of notes that tracks quite well.

André

[stobiepole]

So what are the three mistakes on the layout? I think I have to give this one a try...

Chris

[markusw]

One Q regarding the schem:
does anyone know what the connection from PC2 (pin 13 of the 4046) via R15 to pin 10 of the 4046 is supposed to do?
Any comments would be highly appreciated! 

Markus

[Andre]

So what are the three mistakes on the layout? I think I have to give this one a try...

Chris

They are all 3 missing connections between IC pins, so you need to connect:
1.  IC4 pins 8 & 9
2.  IC4 pins 12 & 13
3.  IC7 pins 13 & 14

You can get the fixed PCB by clicking the link in the first post of this thread.

I also cleaned up the layout :



I only did the PCB layout, so for the offboard connections you still need to use the original PDF.

André

[markusw]

If you mean the harmonizer settings, the clip starts with 3 unison octaves down to 3 octaves up.
After that you hear 3th's 3 octaves down to 3 octaves up and finally 5th's over six octaves.

With every setting of the gain pot, there is a limited range of notes that tracks quite well.

Thanks!!! 

Markus

[Andre]

One Q regarding the schem:
does anyone know what the connection from PC2 (pin 13 of the 4046) via R15 to pin 10 of the 4046 is supposed to do?
Any comments would be highly appreciated! 

Markus

Beats me Markus, it's just 2 outputs connected to each other by an electronic switch.
I checked the 4046 datasheet, but that didn't help much either.
Will check tonight what happens when I remove this connection.

André

[markusw]

Beats me Markus, it's just 2 outputs connected to each other by an electronic switch.
I checked the 4046 datasheet, but that didn't help much either.
Will check tonight what happens when I remove this connection.

André

Thanks a lot in advance. I really don't have any idea about this connection.

Markus

[StephenGiles]

I wonder how much better it would sound from a guitar treared by a fundamental extractor - a lot I'd wager!

A slip of the finger there, of course I meant "treated".

Now if you are content with the mediocre, then fine, leave it as is, but put it through the front end of the EH Guitar Synth first and I think it could be a very nice unit with good tracking.

[Gripp]

With every setting of the gain pot, there is a limited range of notes that tracks quite well.

Doesn't surprise me. I've been playing around with a multiple set of Tim E circuits on breadboard(PWM, XOR Octave, Uglyface and plain dividers).
Sort of a modular square VCO for guitar and for good performance, they all rely on a steady square wave being fed to them. It has been stated before but it just is soo true.
For good performance with these things, you just need to seriously compress and filter the raw guitar signal.
Have you tried running a compressor ahead of it?

[Andre]

Now if you are content with the mediocre, then fine, leave it as is, but put it through the front end of the EH Guitar Synth first and I think it could be a very nice unit with good tracking.

Is this the same one as the EH Micro Synthesizer ?

I've been thinking of using the front end of the Boss OC-2, since IMO this one tracks very well.

Have you tried running a compressor ahead of it?

No, I only tried with different guitars. The ones with humbuckers scored best.

André

[RaceDriver205]

Good on you Andre. Its great when people contribute their work.