GGG ROCKTAVE: HELP ME OUT!

[skullservant]

Alright guys, I need your help! I know I'm not around here much but I have a feeling that you guys can help me finish off this pedal that has been giving me nightmares for the past two months.

I'm building up the GGG version of the Rocktave Circuit, but I'm building it with some mods.

Here is what I'm trying to do with it:

1. True bypass
2. Not use the octave division rotating switch

Now to do the first part, make it true bypass, seems fairly simple to me, just wire the input and the output to a 3pdt like normal, and wire your grounds for both the input and the output to the main ground, which I've done.

Now for the second part, here is what I've done: I did not seat the 4th chip down at the bottom, and I did not connect any wires down at the bottom that would have gone to the rotating switch.

The problem is, when I engage the effect with no power, I get clean signal, which shouldn't happen if the unit isn't powered. As soon as I plug the pedal into power and have the effect engaged, it goes silent. All of the chips are seated correctly according to pictures of completed builds that I have found, and I've wired it correctly, to my knowledge, but again have not seen an actual wiring diagram. I'm hoping it might be a stupid wiring issue and not something more serious.

The chips I am using: LF347N quad jfet, NE570N, and CD4013BE.

If someone can point me to a wiring diagram of the GGG board, or generate one that I might be able to use without the rotating switch, that would be awesome.

Do you think that by not having the 4th chip in place (the one that seems to be doing the division) that that would be causing the silence when the pedal is engaged? Do you think if I seated the chip but did not wire any of the divisions up that the effect would start working?

Below I have taken some photos. The pedal itself will have a green ringer that can go parallel/series, but for the sake of testing I have simply connected the input and output of the rocktave to the effect input and output on the bypass switch. The extra wires are for hooking up the Green Ringer.

If you need any additional photos please let me know!

Thanks for your help!

[duck_arse]

try connecting R11 to the point marked "J". fit R14. it might work, but I haven't read the build docs .....

[dwmorrin]

Your clean signal should always be coming through IC1.
There's a passive path through from input to output, if you treat the IC connections as open... that's one possibility why signal gets through with no power.  That, or, as you said, you've wired something wrong.
Check all your voltages on IC1, and probe the clean path from input to output.  Then worry about the more complicated parts.

[Jaicen_solo]

I tried very hard to build this. My pcb was immaculate and all the components were sourced new but I never got it to work at all.
I'd very much like to get mine going but I can't see anything wrong with it.

[R.G.]

The Roctave is my favorite octave-down. It's (IMHO) much better than any other non-DSP octave down.

Your problem is almost certainly a combination of wiring problems and leaving out the chip you left out. In electrical terms, the chip you left out was in series with the octave signal. Removing it and not subbing in anything else interrupted the path of the effect signal. It is possible to restore function (I think) by sticking in a jumper wire from where the signal goes into the missing 4017 chip to where it goes into the rest of the circuit after the missing rotary switch.

I'm limited to a notebook right now instead of my normal computer "nest" so I can't do the drawings.

I'm disappointed that GGG discontinued this. It's really a sophisticated bass effect. I had one from PAIA long ago; it was truly great.

[mikeford]

I ordered one of the last boards JD had over at GGG.The rotary switch and chip is a cool mod. I think I had to find that particular chip from Steve at Small Bear in NY.

[mikeford]

BTW, you may want to consider contacting JD Sleep over at G.G.G. and ask for the hook-up diagram. There is also an article posted on the chip you chose to omit.
Building the Roctave divider:new sounds more versatility by Mr Craig Anderton is the one I referenced and the followup Craig Anderton Electronic guitar Roctave Divider Modification
I think Scott over at PAIA may also be able to sent you some info.(Check PaiaTalk, his forum on all things PAIA!)

[R.G.]

Leaving the chip and rotary switch out is not your problem, near as I can tell. There are some issues with how you have the missing chip hooked in, but leaving the chip out makes this moot.

Recheck your wiring from pad F near IC3 (NOT the one down by the chip you left out) to the pot it should feed.

Also, check the power supply and ground voltages to each chip.

[R.G.]

Funny how one gets distracted by shiny things.   

The original poster's problem is almost certainly a wiring issue, but it got me all motivated to go look at the Roctave again, and that made me toss the schemo into the design box, and that made me think about the PLL up-octave I've always intended to do, and so ...

Well, I hacked in a CD4046 PLL up-octave. The basics are pretty simple, but it really needs some "politeness" added to be more than just a noise box - which I where my opinion of the Schuman PLL fell. The Rocktave has a good start at this, with the compander chip misused to apply the original envelope onto the synthesized tone, and the melody generator from E&MM did another part. There's some sophistry I like from electronic organ practice, so I'm still dithering on that.

The Roctave does some decent signal squaring and cleaning up on single notes. It needs some help in the upper ranges, but it's pretty good. The signal going to the first 4013 section is pretty good, and the first 4013 output is a good signal for feeding to a CD4046 and its ilk.

With no input, the 4046 will output its lowest frequency, which is ugly, but the compander section should largely mute this. It may need some help from a phase-pulses lock-detector on the 4046; that will need some testing.

I'm not a fan of melodic-intervals generation, so I chose to stick in a CD4024 seven-stage divider for the loop divider to get variable octaves multiplication. Taking the 4046 VCO output to the 4024 clock in and taking Q5 out from the 4024 back to the 4046 phase comparator gives a multiplier of 32 (5 octaves up) for Q1, down to two octaves down for Q6 and Q7, so the original bass divider octaves get preserved out of the 4024; the original 4013 outputs can still be used.

If one is fond of tinkering, one could derive organ-style stair-stepping notes from the five octaves up from the 4024. It takes a lot of resistors, but you wind up with a very voice-able output for making "singing" octaves up instead of the relatively harsh square waves, as the even harmonics from the stair stepping provide the missing even harmonics.

So - questions:
- Do enough people have Roctaves to bother proceeding with this as a mod to the Roctave?
- Is the stair-stepping useful enough to worry about, or is it always going to be a noise-maker?

[Jaicen_solo]

Personally, the concept of additive harmonics is something I find fascinating, and would be interested in exploring particularly if a resonant filter and/or delay is involved.

That said, mine never did work

[jimbeaux]

R.G. +1 on the Roctave Up Mod !

[alparent]

So - questions:
- Do enough people have Roctaves to bother proceeding with this as a mod to the Roctave?
- Is the stair-stepping useful enough to worry about, or is it always going to be a noise-maker?

You are asking the wrong questions!

Will anybody care if I put in all this work into making a great effect into an even better one?

Yes we care!

The rocktave as always been on my build sheet. And I must confess I didn't get 80% of what you wrote.
But if you make a schematic ..... I will build it.

So I'll be waiting patiently.

[skullservant]

Thank you all for your feedback and ideas. I think first I'm going to sort out the wiring and double check it, and then go from there checking voltages and whatnot.

Going to get in touch with GGG about a wiring diagram and go from there!

[Mark Hammer]

The info on adding the 4017 decade counter from the original GP article is on the last page of the scan I have posted here: http://hammer.ampage.org/files/rocktave.pdf

[mikeford]

Oops! I did not realize the article i downloaded about the Mod was from your page, Mark.
Kudos for having it and posting it. i screwed mine up so bad, I had to get Scott lee o'er at Paia to bail me out! If i had a scanner, I could post all the numerous hand written notes o'er the schematic he mailed back to me w/the fixed circuit!

[jsleep]

This is pretty freaky guys.  I started working on this project last night before I knew anything about this post.  I didn't really discontinue the Rocktaves, I just quit etching "in-house" a few years ago  and I've never gotten to re-swizzling this into a manufactured PCB.  I'm working on it.  We never had a wiring diagram for it and I never did build one.  I ALWAYS prototype new PCBs or re-released PCBs now, just to make sure everything is in order.  So this will be something I will be building soon. Now after seeing R.G.'s post I don't know if I should continue?  Is there a better way to build this thing?  Anyone heard from Dean H.  lately?

We have been working pretty steady on getting all those "discontinued" PCBs back up for sale.  Sort of a slow process for one person on limited time.  The ones in-process right now are Stage Center Reverb, Anderton tremolo, Graphic EQ,  Pitch Shifter, Supa Nova and Rocktave also an electronic 6PDT switch.

JD

[Mark Hammer]

Haven't heard from Dean in recent years, but you'd need to thaw him out to hear from him these days anyway.  It is approximately 26 below (Fahrenheit, -32C), with the wind chill there today.    

Oops! I did not realize the article i downloaded about the Mod was from your page, Mark.
Kudos for having it and posting it. i screwed mine up so bad, I had to get Scott lee o'er at Paia to bail me out! If i had a scanner, I could post all the numerous hand written notes o'er the schematic he mailed back to me w/the fixed circuit!

No harm done.  It's their property, not mine.  I just scanned and posted it, back when nobody else seemed to have it up.

[R.G.]

This is pretty freaky guys.  I started working on this project last night before I knew anything about this post.  I didn't really discontinue the Rocktaves, I just quit etching "in-house" a few years ago  and I've never gotten to re-swizzling this into a manufactured PCB.  I'm working on it.  We never had a wiring diagram for it and I never did build one.  I ALWAYS prototype new PCBs or re-released PCBs now, just to make sure everything is in order.  So this will be something I will be building soon. Now after seeing R.G.'s post I don't know if I should continue?  Is there a better way to build this thing?  Anyone heard from Dean H.  lately?

I haven't heard from Dean, but sure, build it. If you want some kibitzing, make the stock Roctave and a baby plugin board to add on the funny divider stuff and have it plug in or stand off on solid wires or something.

A respin of the board would be handy. No aspersion on Dean, but the layout could be much more user friendly.

[Jaicen_solo]

Agreed. Along with the old Smallstone layout, this is the only other effect I never managed to get working.

[Mark Hammer]

I made myself a clone of the original PAiA board, and it works fine, but is about double the size it actually needs to be, and has many of the pads in the most inconvenient places.  The unit could fit into a 1590BB, if laid out a little better, made more use of vertically-mounted resistors, and relocated many of the pads, perhaps with the aid of some jumpers.  Craig needed to read about board layout somewhere before working up this layout. 

I made myself a board using the Hazelwanter/GGG layout, and have not managed to get it working yet.  It is a little more compact than Craig's layout, but not by a lot, and while it does a service by including the decade counter chip , is a little confusing for what to do if you don't want to use it and just go with the basic octave division.

Incidentally, the unit can apply variable treble rolloff to the octaves+fuzz signal, but uses the same rolloff for everything, when really it ought to use something different for the various non-clean signals.  A person might wish to "soften" the f/2 and f/4 signals a little up front, with a little bit of frequency-appropriate lowpass filtering.  Replace both R13 and R14 (10k) with a 5k1 and 4k7 resistor (in series, in that order), and run a cap top ground from the junction of the resistors in each pair.  For the R13 replacement pair (f/2),  run a 47nf cap.  For the R14 replacement pair (for f/4), run a 100nf cap.  These won't totally dull out the octave and suboctave, since their corner frequencies will be 664hz and 312hz, respectively.  But they will make it so that one doesn't have to use the Tone control quite so aggressively.  Note that these suggested additions have no effect on the Fuzz signal.