superfuzz motorboating ... dialed out with the 10k octave pot

[Derringer]

hey

I have it breadboarded and it sounds pretty righteous.
Using 2N5088  Q's, gains in the upper 400s and low 500s ... sounds better than the ~ 2n2222 hfe ~250 that I had in previously

mods:
1. spdt for si diodes/no diodes and a 100kB pot to gnd ... dial in +/- unity w/diodes on the fly
2. 20kB pot between the 0.1uF cap in the mid-scoop section to gnd

It'll motoboat .. bup bup bup bup, and increase or decrease in frequency depending on where the 10k pot is turned. Turn the pot enough and the motorboating goes away. The non-motorboating range on the pot allows adjustment to get the octave sweetness or less octave.


It didn't motorboat with the 2n2222's, however it did make lots of squealy noise with these.


Any ideas what's causing it? Use a smaller range pot for the octave Q's? I might actually just keep it this way so that I can get the funky sounds. When I build it, I figured I'd use shielded cable on signal runs just to be on the safe side if there is oscillation due to lack of shielding.


Thanks

Bill

[R.G.]

Bypass your power supply better. Motorboating is feedback through power or ground in almost all cases.

[Derringer]

the first thing that the battery (9.3v) sees is a 100uF cap.

Maybe what I'm calling motorboating isn't really motorboating.

here's an mp3 that illustrates various settings

http://www.mediafire.com/?lnnnny1iw3m

I am digging the noises though ...

I'm going to go back through the schem with a fine-tooth comb to see if I possibly reversed something

[Derringer]

Q5 was flipped (the right most Q of the pair tied to the 10Kb pot) ... I'm putting in another switch

[John Lyons]

I was gonna say....if the 2N2222's were squealing then something was off.
With 400-500 hfe transistors in there there's not much room left for subtlety is there?
Try the 2N2222s again now that you have the pin out corrected.

john

[Derringer]

nah .. it sounds real meaty now with the high gain trannies ... I'm actually taking a break from perfboarding right now.

THe 2n2222s were in there right .... I just flipped the one Q by accident when I was replacing the 2n2222's with the 2n5088's

Subtle isn't what I'm after for this build   

Thanks for your $0.02 though

did you listen to the clip? I dig the noises ... but I'm weird/wired like that.

[John Lyons]

Listened to the clip. Sounds pretty cool with the straight fuzz and with the chopped modulation as well.
Can you roll back the guitar's volume and get the chop to modulate the guitar's signal?

john

[Derringer]

not quite sure exactly what you mean by modulate ... but the guitar's volume did have an effect on the effect

the lower the guit. volume, the more distinct the tremolo type sound would become

there's a spot or two in the clip where I hit a spot, rolled the volume back, played lightly, rolled back more and the effect increases


hopefully I haven't made any big boo boos yet in the perf board so that I can make some more clips

[Derringer]

ok, done for tonight

the board is done and seems to work, ran leads to breadboard to pre wired pots, switch, and jacks

Hopefully tomorrow it will be a done deal.


Also, correction, there was only one 2n2222 in the circuit the first time. There was also a mix of 3904s and 4401s (think that's the number) ... these all came from one of those radio shack npn packs ... all of the hfe's were around 250 though ... I do remember checking that


good night