This post was updated on .
Another classic gem from the guy who started the DIY craze for me.
This pedal sounds wild and tracks amazingly well (single notes). Tracks much better than the octave doublers I have built. I've updated the layout to use a TL074 and added all the mod options including the extra divisions. The schematic, circuit analysis and mod details can be found in "DIY Projects for Guitarists" and/or from the original 1983 GP article courtesy of Mark Hammer http://hammer.ampage.org/files/rocktave.pdf There are many options to wiring this up, here is what I settled on: The layout was originally designed to be rotated clockwise to fit in a 1590BB. At the time I thought I would end up using a toggle switch to choose between 2 of the extra divisions from the CD4017 mod. But after hearing each available division, I wanted them all ![]() ![]() Of course you don't need to use all 8 divisions from the CD4017, or the jazz, buzz or (buffered) byp options. But here is how I implemented some of the possibilities: I added a SPDT switch to allow the Octave 1 control to select either of the CD4013's "divide by 2" or "divide by 4" outputs. For the Octave 2 control, I used a mini 2P4T rotary switch and have pins 1 though 8 going to each of the 8 division outputs of the CD4017, with pins A & B going to the outer lugs of a SPDT toggle switch and the middle lug of the SPDT going to pin 15 of the CD4017 (though the 1k resistor) ![]() I used SPDT toggles for the "jazz" and "buzz" options. The buzz mod adds even more volume (the pedal is already above unity with the stock R17 value). I may end up using a DPDT so I can alter the value of R17 at the same time keeping the volume consistent when engaging this mod. The BYP connections allows for the original buffered bypass if desired. Verified ![]() Reversed image for the cuts ![]() sample layout ![]() BOM 100R 1k-2 4k7 10k-10 22k-2 30k-3 47k-2 100k-2 270k 470k 680k 1M-2 2M2 5k pots-4 330p 100n-4 220n-2 1uf NP (Jazz mod) 1uf-2 (or use a 1u NP for output cap) 2u2-3 4u7-1 10u-2 100u-2 1N914 1N4001 2N3906-2 TL074 NE570 orNE571 CD4013 CD4017 And a couple other resistor and cap values to taste for the CLR and tweaking the socketed components (see original text for details) mini 2P4T rotary switch (I have a couple I can spare if you don't want to buy a lot of 20) http://www.ebay.com/itm/20pc-Rotary-Band-Switches-DC-60V-0-3A-100-500-ohm-2P4T-10-Pins-2-Pole-4-Position-/300881322642?hash=item460deca292:g:yUYAAOSwRLZT6z-D
1978 Gibson Les Paul Standard, Cherry Sunburst
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Wow. So this thing can do other intervals besides octaves?
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Yes, the divisions mod adds options for divide by 3,5,6,7,8 or 9. You can also combine any one of those with either the divide by 2 (1 octave below) or divide by 4 (2 octaves below).
Check out the last page of this pdf for the corresponding notes provided by each division. http://hammer.ampage.org/files/rocktave.pdf Play an open high E string and the listed note at the same time to have an idea of what it will do. But I can tell you, after doing that myself I thought I would only use the divide by 3 for a cool harmony sound, but the other divisions sound much better than I had expected. Crazy synth like sounds. It's funny, on a couple of the settings you'll think you are on the wrong fret or maybe playing backwards. It might just be a novelty, but kinda cool. It made my think of how the guy from Collective Soul would throw in some wild sounds here and there. The fuzz is pretty thick too. I hope to record a sound sample next week.
1978 Gibson Les Paul Standard, Cherry Sunburst
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Here's a sound sample of the divisions.
https://soundcloud.com/maopedals/rocktave-divider
1978 Gibson Les Paul Standard, Cherry Sunburst
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This post was updated on .
So I added a level control, highly recommended for dialing in unity gain.
I removed the socketed 100k output resistor (lower right corner of board) and took the "Out" wire to lug 3 of a 100k audio pot, lug 2 is the new output and lug 1 to ground. I also re-ordered the 2P4T connections so the divisions are paired more logically when flipping the Octave 2 toggle from A to B. 2 is opposite 4, 3 is opposite 5, 6 is opposite 8, and 7 is opposite 9. Here's the 2P4T switch vero I used, which fits under the main PCB with a thin piece of cardboard between the two. Just trim the legs of the rotary close. ![]() Updated layout: ![]() Updated 1590BB Faceplate: ![]()
1978 Gibson Les Paul Standard, Cherry Sunburst
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Finished putting this together last night using the updated layout (but not the baby board for the rotary). It didn't fire up right away, but I just chalked that up to the fact that it was 5 am and put it aside until I woke up. Sure enough, it wasn't behaving. I was getting fuzz at most but no octaves.
I replaced the 2n3906s with 2n3904s on a whim, swapped their orientation, and the 2/4 octave worked. I poked around until I found that I got the crazy rotary octaves when I added a jumper over the cut between pin 14 of the 4017 and pin 3 of the NE570. Now it sounds great! Glad I got it working. The jazz switch is an awesome addition, definitely helps when I want a subtle craziness and not a full on. BTW, using an electrolytic in the sockets for the jazz switch, I'm waiting for np's to arrive. Thanks for another awesome layout MAO! I still have to upload a demo of the quadrafuzz! |
Wow, sorry you had trouble.
Not sure what to make of it, the design definitely calls for 2n3906s and the orientation on the layout is correct. And I have no idea how jumpering over the cut mentioned brought it to life. But glad you got it working. Looking forward to your Quadrafuzz demo. I have built another one (4136 version), should have it boxed up in a week or so.
1978 Gibson Les Paul Standard, Cherry Sunburst
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It's almost 100% something that I did wrong while building, I'm just glad I got it working and figured I'd share my weird workaround. I'm a solid supporter of your layouts! Keep em coming.
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In reply to this post by SonusFluxa
Thank you so much for that hint! I switched the 3906's for NPNs and inverted them and it worked just fine!!
I started building this pedal 2 years ago and spent many days of work trying to figure out why the octaves didn't work (the fuzz sounded ok). It was hard because I don't have an oscilloscope and don't undertand completely how this circuit works, but it seemed to be some biasing issue with Q1 and Q2 - their output wasn't high enough to trigger the flip-flop's clock. |
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