Edit: According to FSB thread on the subject, the 47p cap on the schematic should be in fact 470p. Layout edited accordingly. Oh. This also makes this 1:1 with Kent EA-3 Fuzz Tone Bender.
Sunday, 30 March 2014
Walco Fuzz Tone Generator
Couldn't find any demos for the original unit. This could indicate one of the two reasons. First, the circuit sounds so horrible that no one has wasted their time to record a demo, or second, the unit is rare and highly undervalued. Either way, designwise it does have distinct differences from other fuzzes of the era. Internet search shows that Mr. Albini has one at Electrical Audio studios, so i guess it can't be all wrong. I added polarity protection and pulldown resistor for this layout. I also tweaked couple of the values to match the ones you have (as there should be 500K resistors and 50n caps..). Same thing with the transistors. Original has 2SC828s in it, but you should be golden with 2N5088s or similar. If you are building this, consider swapping the 47p cap for something a bit higher. Like 10n.
Edit: According to FSB thread on the subject, the 47p cap on the schematic should be in fact 470p. Layout edited accordingly. Oh. This also makes this 1:1 with Kent EA-3 Fuzz Tone Bender.
Edit: According to FSB thread on the subject, the 47p cap on the schematic should be in fact 470p. Layout edited accordingly. Oh. This also makes this 1:1 with Kent EA-3 Fuzz Tone Bender.
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Hmmmm. Interesting.
ReplyDeleteHi there,
ReplyDeleteIt must be a stupid question, but what do you mean when you say "added polarity protection" ?
Many thanks and congrats for this amazing site.
Greg
That's the D1 Schottky diode in series with the +9V. It saves the circuit if you connect power the wrong way (swap ground with hot wire). The price is that you lose some voltage on the diode opening voltage - about 0.2V in case of the 1N5817 in the layout. You can omit it and either just put a jumper where the diode is or connect the +9V to the third row below where it is now.
DeleteMany thanks Csaba Dudas, that's very clear for me now !
DeleteMiro, do you happen to have the schematic for this? Couldn't find it with google, and I tried to trace back from the layout, but what I got is something I can't really understand (which probably only shows my lack of knowledge...)
ReplyDeletehttp://freestompboxes.org/viewtopic.php?f=19&t=24219&p=236663#p236663
Delete+m
47p cap should probably be 470p, but the unverified Walco schematic has it at 47p, so let's see what happens when someone builds it.
DeleteThis means that the Walco Fuzz Tone Generator is 1:1 with Kent EA-3 Fuzz Tone Bender.
+m
Thx, Miro... Should learn to use the search function at FSB...
DeleteChecked the FSB thread. Actually the picture there shows a 47p cap. Indeed 470 is written on it, but according to the naming convention I know it means 47 x 10^0 pF, which is 47pF. Anyway once I find the time I'll build this to see how it works and then I'll definitely play with this cap ;)
DeleteThere are some ceramic caps that do not use the conventional markings. Without measuring i can't be sure. I do know that there are some cheap ceramic caps that are 470p with marking "470".
Delete+m
Either way. 470p should be thin sounding enough.
Delete+m
Verified. A one trick pony, but the trick it knows is not a good one. The Wooly Mammoth has much more sounds and can deliver the sound this one is capable of. The Increase Fuzz pot is a blend between clean and fuzz, but the fuzz sound has a lower volume, so the mix doesn't work too well. Tried 47p, 470p, 1n, 2.2n, 10n. The higher you go, the more is the fuzz and the high content. Yes, the high content. Also tried several transistors (2n5089, 2n5088, 2n3904, BC550, BC549 and 2n2222) they are more or less the same. Oh yes, if you want the conventional direction of how the fuzz is added (clockwise -> more fuzz), then the pot lugs need to be swapped.
ReplyDeleteWell you can't win them all I suppose :o), but thanks for verifying buddy!
DeleteDon't get me wrong, it's always fun to build these things whatever the result is ;) With telling how it sounds I just wanted to reflect to the part in the description that there is no info available about its sound. I'd love to make a demo video but I don't have the gear for that. And maybe somebody will build this and find that he needed this sound. But it did not convince me... And of course thanks to miro for the layout, I love these compact quickies :)
DeleteI'll swap the wire labells once i get back home.
DeleteThe layout doesn't stretch to it, but adding 220R resistor and 22µ (or even higher) cap parallel from Q2 emitter to ground instead of putting it straight to ground - that should give a whole lot more gain out of the "fuzz" transistor. Just a thought...
+m
Hm... Q2 is the upper one, right? I'll give that a try sometime... It would be nice to have a small 1590A capable fuzz to make my board a bit smaller.
DeleteYes. The upper one. You could also try lower values for the 820K. That value seems pretty odd to me in that position.
Delete+m