Once again -- cap orientation on Univox/Shin-Ei Superfuzz schematic

[mordechai]

I am trying to find a schematic where the orientation of the 10uF electrolytic caps in the Superfuzz circuit are properly represented in the schematic.  On the schematics I've found here, the + side of the caps are not represented...I did find a schematic where the polarity orientation was included in the schematic, but in that schematic it looks like they're (accidentally) oriented for a positive ground circuit, so I am wary to follow it. 

I posted about this earlier but didn't get any replies...would appreciate help here.

[Derringer]

this should help


but it is a modded schem
i ditched the 10 uf cap that's between the diodes and the balance pot
but if you leave it in, I don't think it would matter which way it was oriented because there shouldn't be any DC at that point anyway

and that 10 uf 5v electro in the power supply is just silly
go with at least 47 uf 16v and throw in a 100r - 220r resistor to make a real low pass filter

[mordechai]

Really helpful Derringer, thanks a lot!

[Derringer]

you got it

and for what it's worth, when I built one for a friend, I really liked using this PCB
http://ustomp.com/?p=12

[mordechai]

That's a great resource, thanks.

If I WERE to leave the 10uF cap between the diodes and the expander in the circuit, would I orient it the same way as the 10uF right before the diodes (i.e., with the positive end facing the input)?

Good idea re: replacing the 10uF off of the power supply with a higher value.  I've seen a neat high gain fuzz design where following a 100R series resistor, there was a .0047uF poly film cap followed by a 100uF cap in parallel.  Would that combination work well here for some added noise filtering?

[Derringer]

polar electros are designed so that their positive end faces the direction of higher DC voltage
at that particular place in the circuit, there is no DC voltage, so I don't think that the orientation matters, nor is there a need for a cap. You can just use a jumper instead of the cap

But yes, the template from ustomp has the cap in question oriented the same way as the preceding cap.

And yes, the power supply filter you described will work just fine

[mordechai]

Thanks again.  I am excited to try these modifications (and I'll try using a jumper instead of that 10uF).  I think I might also add a "starve" pot at the front of the circuit to limit the voltage...I saw a demo on youtube of someone who did this with their version and it sounded really interesting. 

[mordechai]

In addition -- what about changing the values of the controls.   Would decreasing the expander (to, say, 25KB) alter the shape of the fuzz, or would increasing the level (to 100KB) let out a little more low end?

[Derringer]

because those coupling capacitors are so freaking huge (10 uf) you shouldn't hear any difference in frequency response by increasing the value of the potentiometers
on mine though, I did change the balance pot to a log pot just because I like that taper better.
I didn't try a log pot for the expander but I am happy with the linear taper there anyway

the starve circuit would be a variable resistor, like a 5K pot, wired in series between the battery and the rest of the circuit ... so as you increase that resistance, the voltage sags (starves) and you get a different sound
I've read that multiple people really like this mod but it's something I've never tried.

[mordechai]

I've tried it on a silicon tonebender (used a 10K pot...5K works too as you suggested).  It does weird things to the tone in a really neat way.  Gave it a more compressed sound, a little "scritchy" or fizzy but in a pleasing way, with a touch of an octave overtone surfacing.  I think that in an all silicon circuit like the superfuzz it is a cool function.  Here's a link to a guy on youtube who did it with his, so judge for yourself:

http://www.youtube.com/watch?v=BPBn1VK8C-M

Regarding Q4/Q5 -- do you think the character of the octave would be affected if the Hfe of these matched trannies were lower that the rest, like ca. 90-100 Hfe?  I have a few low gain NPN silicons that I might want to try...