Fuzz Face (Mangler) Power Filtering

[Rockhorst]

Not sure if this is the right subforum, between general, tech and mods there seems to be a bit of a bleed through. Anyway, here it goes.

I build a NPN Mangler/Fuzz Face with some excellent OC type transistors. I totally love the pedal, but I noticed it's a bit picky running of power supplies (I loathe batteries, not an option for me). It mostly works fine on its own, but daisy chaining in any way induces noise. It works well with a Visual Sound One Spot, but there's a background whine when using a Godlyke Powerall (similar to what I noticed when using it with a Mosfet Boost aka Thunderpuss).

This got me thinking about better power filtering options in the Mangler (and Thunderpuss). One idea that I've seen a lot lately is using a film cap in addition to the electrolytic cap because they apparently don't work equally well on all frequency bands. What value would be appropriate? About 100nF would be my guess. Is higher better?

Also, usually there's also a small resistor used for power filtering, like 100R. Will this mess with the function of the 470R resistor in the FF circuit and would lowering it to 10R still have some filtering function?

Also, I've understood from Brian that a RoadRage would take care of some filtering when using PNP transistors and having them work at 9V. Is there a way to utilize the Road Rage for +9V? (I'm guessing that this won't work with a 9V regulator?)

Anyway, any other tips and insights into filtering the power in this type of circuit are very much appreciated.

[stecykmi]

you may see some benefit from using a film cap in parallel with a large electro cap, however it's not necessarily a sure thing. bigger is most definitely better, i would use the largest value you have on hand.

100R would probably be okay because 100R is very small compared to R2 (33k) and the bias trimmer can compensate for the "extra" 100R. however, any small value here will perform the power supply decoupling you're looking for.

the road rage does not filter the input +9V so it won't be useful here. A 9v regulator (the 7809) will work very nicely, however you need to supply with with at least +10V for it to function, meaning a one spot won't work.

for maximum filtering, I would first put a large electro cap (at least 47uF) to ground, followed by the small resistor (10R to 100R), followed again by a large electro. the 2nd electro can be the on-board cap (C4 on the mangler). if you choose to try a film cap, I would place in parallel with C4.

[Rockhorst]

Hey thanks Stecykmi. Will try that.

[stecykmi]

let us know how it turns out!

[Rockhorst]

Will do. I'm busy with a FF PCB attempt in Eagle and I've implemented your suggestions. Took a bit of effort to get everything as neatly laid out as I had it before, but I'm getting there

[jvg13]

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