Roctave Divider wiring "issues"

[pandadandan]

Ok.
This isn't my usual fuzz build, so after populating the board I am now at the wiring stage. 

And I'm totally stumped.

here's the layout:
http://www.generalguitargadgets.com/diagrams/rcktavpl.gif
the schematic is in here (PDF):
http://hammer.ampage.org/files/rocktave.pdf

"IN", "OUT", "S1" and just good ole' grounding
are my main issues.

I'm just used to one pad for in and one for out and wiring it all up with a 3pdt, so it's throwing me quite massively.
I checked the schematic and I see that of the two pads for IN and OUT, one is going to ground.  So do I connect the jack sleeves to their relevant ground ends?  Can I jumper the on/off switch and wire a 3pdt?  Is that pointless?  Is grounding to only the in/out jacks fine?

Many thanks in advance.
My mind is haemorraging.  Just when I thought I was getting the hang of reading schematics too.......

[the recluse]

The rocktave is the one project that I attempted and was never able to get to work 100%.  The circuit is supposed work as a buffer when the effect is bypassed.  I believe you need to leave s1 open in order to get the effect, so jumpering the switch would leave the effect in bypass mode.  I eventually gave up on this one, good luck!

[pandadandan]

I'm 100% not going to give up on my first non-fuzz project.
I plan to compile the information I've found so far and offer it to the GGG site after I'm done as, compared to the other projects on their site, there isn't much documentation.


Here's what I've learned from this site so far:

I've learned so far from trawling this site about jumpering the stereo mod section and rewiring the Divide by 4 pot for the 4017 mod, which aren't mentioned on the GGG site, so I'll put those ones up on their site when I finish this.

So now queries are these:

Wiring up the Ins / Outs.  As there are two pads for the ins and outs, how would I wire them?

eg Input -
Tip goes to the upper pad to C2 (this seems fine according to the schematic), but does the ring or sleeve go to the connected pad? I'm guessing the ring, but I could be wrong.
Output Jack seems more straightforward. Tip to upper pad, sleeve to lower pad?

Grounding.  Just everything as usual wired to the pots and sleeves of the ins and outs.?

Finally, the switch. Is this a latching "normally open" SPST switch?

[Dean Hazelwanter]

Hi,

Tip goes to the upper pad to C2 (this seems fine according to the schematic), but does the ring or sleeve go to the connected pad? I'm guessing the ring, but I could be wrong.
Output Jack seems more straightforward. Tip to upper pad, sleeve to lower pad?

With both the input and the output, it's tip to upper pad and sleeve to lower pad. If you want to turn on power to the effect by inserting the input plug, then connect the negative terminal of the battery to the ring connection on the input jack.

Grounding.  Just everything as usual wired to the pots and sleeves of the ins and outs.?

Yes, or you can use any of the pads on the left and right perimeter of the board, marked 'G' as grounds.

Finally, the switch. Is this a latching "normally open" SPST switch?

It's an SPST stomp switch to enable the effect. Push it once, it's on, push it again, it's off.

Recluse, If you get the urge to take another whack at it, I'll try to help.

[pandadandan]

Hi,

Tip goes to the upper pad to C2 (this seems fine according to the schematic), but does the ring or sleeve go to the connected pad? I'm guessing the ring, but I could be wrong.
Output Jack seems more straightforward. Tip to upper pad, sleeve to lower pad?

With both the input and the output, it's tip to upper pad and sleeve to lower pad. If you want to turn on power to the effect by inserting the input plug, then connect the negative terminal of the battery to the ring connection on the input jack.

Grounding.  Just everything as usual wired to the pots and sleeves of the ins and outs.?

Yes, or you can use any of the pads on the left and right perimeter of the board, marked 'G' as grounds.

Finally, the switch. Is this a latching "normally open" SPST switch?

It's an SPST stomp switch to enable the effect. Push it once, it's on, push it again, it's off.

Recluse, If you get the urge to take another whack at it, I'll try to help.

Amazing.  Thanks for the reply

This place makes me smile.  Time to fire up the iron.....

[the recluse]

Recluse, If you get the urge to take another whack at it, I'll try to help.

Thanks for the offer Dean.  I'll keep that in mind, but I have begun to cannibalize the built for parts, and I think the enclosure will be used to house my upcoming Dr. Boogey build.  IF I do revisit it and am unable to ssus it out, I'll be sure to look you up.

[Mark Hammer]

About the "bypass" switching on the Rocktave....

In a "non-inverting amplifier", such as is used by things like the Tube Screamer and Distortion+, etc, etc, the gain of that stage is set by (Rf + Rg)/Rg, where Rf is the feedback resistance and Rg is the resistance to ground.  One of the quirks of that is that its gain can never go below x1 (i.e., will always be at least x1), since Rg is in both the numerator and denominator.

IC1a (following the Anderton schematic) is configured as an "inverting" amplifier.  In such a configuration, the gain is set by the feedback resistance divided by the input resistance.  One of the quirks of that configuration is that gain can go below x1, simply by making the feedback resistance smaller than the input resistance.  One tends not to see it that often because there aren't that many reasons to want to waste an op-amp stage just to reduce signal level.  In this case, however, it is used productively.

Note that as in just about every other octave divider, there is a 4013 flip-flop used in this circuit.  The 4013 is going to require an input signal that is a large enough amplitude that it will trigger a flip-flop action.  If the signal fails to meet that threshold you get neither flip nor flop.  Indeed, that is one of the reasons why octave-dividers misbehave so often; because there are points in a signal's "lifetime" where sometimes it meets that criterion and sometimes it doesn't, all within the space of 200msec.

What Anderton does in this circuit is use the gain<1 properties of an inverting op-amp to drop the signal level that gets fed to the compander chip (IC2).  So, the footswitch changes the feedback resistance in IC1a from 680k to zero ohms, with the result that there is insufficient input signal amplitude to generate either flip-flop OR fuzz, leaving only clean signal from IC1b and IC1c.  IC1b provides a wee bit of gain (x1.7), just for "signal hygiene" purposes. 

Purists may wish to use true bypass switching to sidestep the entire circuit, instead of using S1 as shown, though I can't see that resulting in much improvement unless you use poor op-amps (unlikely in the original PCB layout for a 4136) or have lousing wiring practice.  On the other hand, I can see a place for using a stompswitch for complete bypassing, and a second momentary switch for defeating the octave-generation on a riff-by-riff basis.  The challenge of that, however, would be to have appropriate level-matching, since complete bypass reverts to unity-gain and internal "electronic" bypass reverts to a gain of x1.7.

[pandadandan]

Well, it's all finished up but not yet in a case.  Save for a crappy chip for the flip/flop which needed replacing, worked 100% perfect straight away.  Jeez it's LOUD.  I almost wiped out my eardrums when I clicked it on.



No noise issues at all.  Bypass switching is nigh on transparent.  I'm a very happy bunny!  Many thanks to Dean and Mark for both their kind words.  I'll write further when I have chance.