Very Noisy Foxx Tone Machine FTM

[Stratomaster]

Hello,
     I've built the FTM on JD Sleep's GGG website using his board.  I know that fuzzes are inherently noisy, and I understand this.  However, the noise from this pedal is ridiculous.  It's almost dead quiet when in Octave mode, however, which clues me in to it not being a grounding issue.  Also, it frequently picks up radio stations.  I've added the small value cap across the input jack with not much success in fighting this.  Any ideas on how to make this a little quieter?  Thanks in advance.

[tcobretti]

It's funny that you bring this up, cause I just built one today.  Mine is actually pretty quiet when not in octave mode, and I've got high HFE transistors in it.  Something is wrong with your pedal.  I'd check the wiring and make sure nothing is physically contacting the board.

BTW, mine is amazing.  I hadn't built it because it was too complicated for vero.  But now that I'm burning PCBs I figured I'd check it out, and mine freaking smokes!  I'm trying to decide if I want to box it with a stomp spst so I can switch octave on/off while I'm playing. 

I used the layout on Fuzzcentral, and it fired up first time after I got the battery wires oriented the right way!

[solarplexus]

maybe it's a little OT, but I'm wondering if it's possible (and if it would sound nice) putting 2 AC128 in place of the diodes in the foxtone... I have the danelectro french toast and it sounds GREAT despite what some people might think.  I changed the diodes for 1n34A but I have 2 Ge trannies lying around and always wondered if it would work. ?

[tcobretti]

Yes it should work, but it should be about the same as using Ge diodes.  The Base and Emitter of a Ge transistor is essentially a Ge diode.

[Stratomaster]

I'm very glad to hear that this pedal can be done successfully with very little noise.  However, this does not change the fact that mine is still noisier than hell on a hot summer day.  I'm using the transistors called for on the GGG website, so they aren't something I tossed in there.  Any ideas?

[tcobretti]

Have you tried different transistors?  If you used Ge transistors, a symptom of high leakage is lot of hiss.

[Stratomaster]

All NPN Si.  I swapped out a MPSA18 for Q1 and 2N3904s for the rest.  This seems to have helped calm some of the noise, but it's still excessive.  I tooks some readings and they are below.


Batt: 8.7 V

Q1
c 2.53
b 0.80
e 0.13


Q2
c 6.47
b 2.53
e 1.90

Q3
c 7.05
b 0.77
e 0.16

Q4
c 7.54
b 0.75
e 0.18

[R.G.]

By definition, a "weed" is "any plant growing where you don't want it".

Likewise, "noise" is "any sound you don't want to hear".

You don't mention what kind of noise. Hiss? "Angry sounding" hiss? Hum? Buzz? RF pickup? Clicks? Bursts of static?

All of those are noise, and they are all indicative of different problems.

If your problem is thermal hiss (so-called white noise) then it comes from either a badly noisy resistor, a damaged transistor, or a bad solder joint. In a new build, bet on the bad solder joint. I would first go back over the board with a soldering iron making really certain I had good joints, and only then getting into the esoterica.

[Stratomaster]

The noise is a very bassy hum.  Not really a hiss or crackle.  It's not 60 Hz hum either because it does it with humbuckers and in the 'out of phase' positions on a strat.  Any ideas?

[R.G.]

It's not 60 Hz hum either because it does it with humbuckers and in the 'out of phase' positions on a strat.

That does not follow. The circuit itself can be picking up hum whether the guitar pickups produce hum or not.

A really bassy hum usually IS 60 cycle.

So take your DMM set to ohms and check continuity from the input jack ground connection to every place on the schemo where it's supposed to be ground. It's likely that one or more are not connected.