Univox Superfuzz and Shocktave by Joe Davisson mixed together

[Cortex]

Hi good people.

I'm really diggin' the superfuzz. I was thinking if we could add an octave down to it. There is a hint of some octave downess in there already but something that will give it that crazy sublevel underneath craziness. Shocktave looks like a simple enough idea.

I was thinking about Jack Orman's jfet splitter circuits, maybe we could split the signal in two, then run it through the superfuzz and shocktave respectively, and then either mix it in the end, or maybe blend the shocktaved signal somewhere before looking at the superfuzz schematic. Before the diodes maybe, or maybe even before that.

How should one achieve the signal mixing? how to prepare signals for the mix? I presume one would have to match impedances, levels, filter the signals in some way?
Definitely looks like a handful to me and my level of stompbox building but I am really ready to experiment, and of course to learn something new out of it, with your help.

ANy thoughts?

[slacker]

You can just connect the two inputs together, the shocktave has a high input impedance so it shouldn't interact with the input of the superfuzz. If you feel like experimenting you could try removing the first two transistors from the shocktave and use the input stage of the superfuzz instead, take the output from before the superfuzz expander pot and feed that into the octave down part of the shocktave.
If you look on the shocktave schematic you'll see that the mix pot takes the octave down signal on one side and the straight sound from the preamp on the other. You could disconnect the straight side and connect that side of the pot to the output of the superfuzz tone switch instead, the shockktave output pot would then replace the superfuzz balance control. This would give a mix of superfuzz and just the octave down from the shocktave. This should work only the shocktave may be a lot louder than the superfuzz, you could add clipping diodes on the shocktave side to reduce the volume.
Another way to mix the signals would be to use resistors from the wiper of the shocktave output pot and the superfuzz balance pot to the cap that follows the balance pot.

[Derringer]

I have routinely run my shockatve in front of my superfuzz and it does indeed sound awesome

[Cortex]

Thx guys!

If you look on the shocktave schematic you'll see that the mix pot takes the octave down signal on one side and the straight sound from the preamp on the other. You could disconnect the straight side and connect that side of the pot to the output of the superfuzz tone switch instead, the shockktave output pot would then replace the superfuzz balance control. This would give a mix of superfuzz and just the octave down from the shocktave. This should work only the shocktave may be a lot louder than the superfuzz, you could add clipping diodes on the shocktave side to reduce the volume.

Wow, this seems like a great idea! I GOTTA try this. Thank you so much. I could put a switch that could be an octave down switch, and have a stock superfuzz and a hot octave down roded one in the same enclosure. Fantastic.
But isn't there some way to know up front how much will the shocktave be louder? and of course the way to prevent it? you did mention clipping diodes. Couldn't we add a simple volume control just before the shocktave Mix pot that would be adjusted to taste? just trowing ideas in the air...sorry if it's obvious to you that this can't be done heh.

[Mark Hammer]

Chatting with fellow forum member alparent this morning (we work in the same building), the topic of the 2SC1583 matched NPN pair came up.  And it got me thinking: would using a 2SC1583, or some other matched pair (e.g., trannies in a CA3046), for the "mirror" pair in a Superfuzz improve the octaving?

I ask this because the entire point of that mirror pair, and the phase-splitter preceding it, is to end up with two well-matched versions of the input signal so that there are twice as many equal peaks where there used to be one.  Having twice as many peaks, but alternate peaks have slightly different amplitudes, would not, in principle, result in as effective or robust octaving.

Now, I am well aware of the trimpot addition/mod that  provides for varying the base-to-ground resistance for each of the transistors in the mirror pair, but it only does so in reciprocal fashion.  That is, any resistance you take away from the one, you have to give to the other.

I'm wondering if a matched pair would improve on this a little.

Opinions?

[DougH]

Matching transistors in the pseudo-differential pair makes little to no effect as long as you have accurate signal matching (albeit 180 degrees apart) coming out of the phase splitter. I have a fuzz like this with a super-accurate phase splitter and tested all kinds of crazy mismatches in the diff pair and they all produce strong octaves. And in fact, each tested configuration varied very little, if at all, in sound.

[Mark Hammer]

So does/would one get more mileage out of, say, having a trimpot on the ground or V+ side of the phase splitter, and tweaking it until one gets very close matching of output amplitudes from the emitter and collector of the phase-splitter?

[DougH]

I don't know. I didn't use a transistor for the phase-splitter in mine.

[Quackzed]

I have routinely run my shockatve in front of my superfuzz and it does indeed sound awesome

I would think that running it the other way around would be even awesomer!
a tonebender or bassy fuzzface into the shocktave is awesome as well.

[Derringer]

you know, I haven't tried that
and there's no reason not to

I'll get back to you on that 

[azrael]

I had problems getting an Ibanez Standard Fuzz (Very similar to a SuperFuzz) to get an octave up until I matched a transistor pair. 

[Mark Hammer]

Lest I create some sort of micro-meme that sends people off in a wild goose chase, let me emphasize that matching of the two rectified signals IS important in getting a decent octave sound.  But let me also emphasize equally that there are a number of different elements in the circuit that can impact on the evenness of those two signals to be combned.  So, the matching of the transistors CAN matter, but so can the matching of rectifying diodes, the matching of the two equal-value resistors on the emitter and collector of the phase-splitter, and any other components between the outputs of that phase-splitter and the point where their two outputs are combined.

In general, one is aiming for equal rectified signals that produce two equal peaks where there used to be one, and however you tinker to produce it is perfectly fine.  For my part, I have absolutely no idea what to select for, when it comes to the mirror pair, so my original question was guided by the assumption that if the pair was matched in a package, then I might have one less thing to tweak in search of a better octave sound.