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Thoughts on a fuzz problem?

kiki_90291

Member
Messages
4,371
So I built a MKII clone (from General Guitar Gadgets, matched germanium NPN transistors from Small Bear). It sounds fantastic on batteries, but I really hate having to worry about batteries going out and not leaving things plugged in, so I built it with a power jack. When I plug it into my Pedal Power (on it's own jack - positive ground) - I get this amazing white noise. I'd call it background, but it's very audible - definitely would not be unnoticeable even at gig volume. Is this a general issue with germanium fuzzes? If not, can anyone recommend a good MKII style fuzz that plays well with a Pedal Power?
 

lowbrow

Member
Messages
772
NPN transistors are for negative ground circuits. If you built the pedal to acommodate them, you would not want to power it off your positive ground supply. Try powering it with a Boss adaptor and see if the noise goes away.
 

hazmat33

Member
Messages
934
I have a MJM FX Brit Bender (2-knob) and it works fine with a PP with its own jack. There's a few in the emporium at very low prices.
 

kiki_90291

Member
Messages
4,371
NPN transistors are for negative ground circuits. If you built the pedal to acommodate them, you would not want to power it off your positive ground supply. Try powering it with a Boss adaptor and see if the noise goes away.
Yes - you're correct (I built it a while ago and had to look at the schematic again). It is a negative ground. I have tried it with the PP2+ and with a OneSpot (which is way, way noisier!). Is there a enough of a difference in a Boss adapter?
 

lowbrow

Member
Messages
772
Yes - you're correct (I built it a while ago and had to look at the schematic again). It is a negative ground. I have tried it with the PP2+ and with a OneSpot (which is way, way noisier!). Is there a enough of a difference in a Boss adapter?
No, a OneSpot and a Boss are both center negative, so there should be little to no difference. It sounds like you have a ground issue. If it makes the noise on a power supply but not a battery, those are clues to help troubleshoot where the problem is. Look carefully at how you have the power jack wired into the circuit.
 

basicaudio

Member
Messages
1,416
Try a 100 ohm resistor in series with the power wire to the board
with a 100uf cap to ground after the resistor.
 

ChargerSG

Member
Messages
241
Yeah, NPN is usually center negative.

PNP usually positive center.

Yeah try a small resistor (47-100 ohms) in series from the 9V to power on the board like Basic Audio said. You probably won't need that 100uf cap though, these kits come with a 47uf power supply filtering, just not a resistor limiter.

If none of that works, just use a battery. I think it sounds good, and if you unplug the input jack a battery can last months, especially with a fuzz.

Keep in mind you can put a toggle switch to disconnect the battery too, if there's room. Then you wouldn't have to unplug it every time.
 

amphead777

Member
Messages
3,681
I would stick with batteries. Unlike with an OD, fuzzes use very,very little power. If you changed it once a month you would have no problem whatsoever. I have some fuzzes that have had the same battery for a year!! That's not uncommon!! It also uses the cheap Dollar Store batteries. Plus, batteries sound better.
 

kiki_90291

Member
Messages
4,371
You say it sounds fantastic on batteries - by fantastic I'll presume there's no doubt that the transistors are A) NPN, not PNP - what are they BTW?.. and B) oriented properly. OK, so if that's not an/the issue, then you've wired either one or both of the input/output jacks or the DC jack impreoperly. Since it works on battery, we can assume that the in/out jacks are at least wired correctly as it relates to the signal. Some wiring schemes use one or both in/out jacks as part of the total ground - some don't. If there's no ground issue involving either of those as it relates to grounding the entire box, then we can look to the DC jack and/or the ground pad(s) on the board. You say you've wired it according to an NPN wiring schem, right? Since you built a GGG unit, which of the GGG schems did you use? There a a half dozen or so of them on their site and of course there are others out there too. I've built several MK I, MKII, amd MKIIIs some of them GGG boards - all work with their respective power sources and are absolutely quiet. We can figure it out with more detail.
Thanks for the input - here's some more info:

I used this layout here: https://www.generalguitargadgets.com/pdf/ggg_tb_m2p_lo_ng.pdf

And these transistors:

http://www.smallbearelec.com/servlet/Detail?no=882

I just checked the wiring - everything appears to be correct to that layout. It sounds great and is dead quiet with batteries. It plays fine on the power supply - i.e., it still sounds good with teh same fuzz tone, so the effect doesn't go away or die off, but the PP2+ adds a distinct hiss (not crazy loud, but signficant. I plug it into the One Spot and the hiss is prominent. I have to take off tonight, but may try to post some recordings tomorrow, if that helps.
 
Messages
1,871
Hmmm. It's true, you can run a battery forever, but depending on the input jack you used, it may be an "always on" situation. That's a real easy fix, just wire an SPST mini toggle into the hot battery wire and ground it to the enclosure. Flip it off when you're done playing and there will be zero battery draw, then as the others have stated the battery will last forever. We should nail down the objectionable sound when powered though. The OneSpot is one thing, but the PP2 is a regulated isolated supply so there shouldn't be any difference from the battery power. Let's start with a recheck and reflow of the all grounding points POST the DC jack. We can try another wiring scheme as well. Some voltage measurments from the transistors would help also.
 




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