'69 or '70 Univox Super-Fuzz Troubleshooting

[sacakl]

Hi all -- First post so please go easy on me.  I've mainly built BYOC pedals in the past, which is soldering by numbers, but I have a question about possibly doing some work on vintage fuzzes.....

I have a few original graybox superfuzzes and each seems to be slightly different -- one seems to be total mayhem, another with more of an octave effect, and another one that's in between.  I like the one that's in between the best out of the 3, and I've heard that there were some variances in the components between these fuzzes that might explain the differences in sound. 

How would I go about measuring this and perhaps duplicating the sound of the one I like most accurately?

[joegagan]

i have not seen one yet that did not need all of the many 10uf electrolytics replaced. if it were up to me, this should be a standard thing to get a baseline on at least that parameter. they always sound much better after.

you can check hfe of the transistors. resistor and cap values that changed over the years could also make big differences.

other people have gotten very scientific about matching or not matching gains of certain trans in the circ for max octave effect, etc. i have worked on vintage ones but not enough to delve that far in. if you search the older threads, there is a wealth of info here about making these babies sound  -------- super

[Mark Hammer]

Joe is spot on regarding the likely need to replace electro caps that may well have gone off spec in the intervening 45 years.  It happens....and often enough that I can't see anyone you might eventually sell the pedals to making a stink about the caps not being "original".

But as many here who have made a Superfuzz can attest, even with brand spanking new caps, more robust octave sounds can rely on a bunch of other stuff to align.  Reasonably-matched mirror transistors can help.  The trimpot for balancing the signal going to each of those transistors, can also help, as well as matching the 470R resistors, and maybe even tweaking the the 10k emitter and collector resistances on the phase-splitter stage.

Ideally, you want to have two equal versions of the rectified signal, such that when you add them, you end up with two equivalent "humps" (on the scope) where there used to be one.  And there are a couple of different points of intervention that can produce that matching for you.  So, for example, working a trimmmer might be easier and acheive the same result as matching the mirror pair.  Four quarters, ten dimes, or two quarters, three dimes and 4 nickels all add up to a dollar, right?

Do note that I am only talking about what produces a frequency-doubling effect, here, and not about what makes for a kickass fuzz.  That's not to say that the more you have of one the less you are going to have of the other.  But in general, whether you are talking about a Superfuzz, Fender Blender, Foxx Tone Machine, Octavia, or Green Ringer, the obviousness of the octave rests on the matching of two complementary rectified signals.

Joe is also right that there are a great many very informative threads and posts on the SF, so don't stop here.  Search away!

[sacakl]

Thanks guys.  Much appreciated.   I wonder if I actually prefer the one that has some drift in it.  I'll also do a search as well.  Thanks.