Modded my BMP, now have noise and feedback

[Guitarfreak]

Today I performed the Tone Wicker mod to my NYC BMP which bypasses the three 470p caps on the gain stages.

http://fuzzcentral.ssguitar.com/schematics/bigmuffpischem.gif

The mod went well and I like the effects, but now when the pedal is in effect the noise is much greater than before and it seems to feedback much easier than previously, but the pedal still works.  The feedback seems irrelevant to the mod switches position while the noise is much more present in the bypass position.  This makes sense because more HF is coming through, so more hiss.  Any ideas why I am getting more feedback than before the mod?  Things to look into?  I have to leave for work in a few minutes, but I will return and answer any questions later tonight.  Thank you in advance.

[Guitarfreak]

Alright I'm home now.  There also seems to be a squelchy, touch-sensitive, almost oscillating sound behind the tone which is particularly noticeable on palm muted chords.  Not sure I ever noticed this before, but it's happening even with all mods bypassed.  I touched up a few other things while I was in there so something might have come loose or something, still not sure.  More info needed?  Don't be afraid to ask questions.  It almost sounds like a feedback loop, but I don't know what I could have done that would cause that.

[paulyy]

Just a shot in the dark but you can try using sheilded wire for your inputs and outputs.

[Earthscum]

in my experience, you're actually better off switching out the 470p's for something around 220p-100p. This will give you the high end sparkle that you are looking for, but will cut the audible hiss and squeeling out. The lower the cap, the higher the frequencies that are cut. Even 10p will help stabilize the pedal.

Remember caps in parallel are added up, so if you find a good cap that stabilizes the sound, then you can switch in the 'rest' of the cap (say you use 220p, just switch in another 220p or 270p in parallel and you got almost the stock value).

[Guitarfreak]

Just a shot in the dark but you can try using sheilded wire for your inputs and outputs.

I've been meaning to pick some up.  What do you recommend?

[paulyy]

Smallbear sells some. Never tryed it but should work. Heres the link http://www.smallbearelec.com/Detail.bok?no=796
or you can go to home depot and get some shielded wire for dirt cheap. Its pretty much the same stuff smallbear sells.
Id also try doing what Earthscum said to do too.

[Guitarfreak]

in my experience, you're actually better off switching out the 470p's for something around 220p-100p. This will give you the high end sparkle that you are looking for, but will cut the audible hiss and squeeling out. The lower the cap, the higher the frequencies that are cut. Even 10p will help stabilize the pedal.

Remember caps in parallel are added up, so if you find a good cap that stabilizes the sound, then you can switch in the 'rest' of the cap (say you use 220p, just switch in another 220p or 270p in parallel and you got almost the stock value).

That's true, thanks for the input.  You know, I was actually thinking of something along those lines.  I was thinking of lifting the cap on the buffer stage and keeping the ones on both of the gain stages.  Not sure how that would sound compared to having three smaller caps on each stage, no doubt it would sound different.  I am afraid that it won't give me enough headroom.  I like the new breathing room I've found in the pedal since the mod.  To be honest, the noise doesn't even bother me, I use the pedal for doom tone so it's not a big deal as far as noise goes.  If I can get rid of the feedback though that would be killer.

[Guitarfreak]

Really dumb question.  So when you say shielded wire do you mean a single insulated wire with a foil shielding, or do you mean an insulated wire and bare wires wrapped in a larger coat of insulation?  I would hope that it is the previous, but I am finding much more of the latter.

[Earthscum]

The braided shielding is much better, from what I've been gathering, than the foil. Basically, the ground point on the foil stuff is a wire that, you hope, is making contact with the foil inside. I used it on a tube pre, and it was a pain in the arse to work with. The braided stuff is easy... you just strip the braiding back, strip your wires, tin everything and solder it. Also, not that it matters as much in a stompbox enclosure, it is a load tougher.

If you have a couple 10p or so caps, try them out, you could just hold one across the second gain stage and probably drop a bunch of the unwanted noise. I just tried a single stage BMP with an MPSA13 running Si+Ge against Si+Ge, and dug the sound, but it was getting a lot of gain feedback and squealing. Was instantly cured with a 68p without loosing any apparent clarity. 150p started to really shave the tip-tops off, 220 was very audibly smoother, and 560 was right in that warm area.

[Guitarfreak]

Is this what you are referring to?

http://www.guitarelectronics.com/product/WA4/Cloth-Vintage-Style-Wire-with-Braided-Shielding.html

Do they have 22 guage braided shielded wire that comes with standard insulation?

[Earthscum]

http://www-ese.fnal.gov/eseproj/BTeV/TestBeam02/Cables/DataCables/Assembly_100ft_files/image010.jpg

See how there's braiding? Then there's foil underneath. One type has just the foil with a conductive wire that contacts it for termination. The other style is like what's show, but most I've seen and used doesn't have the foil underneath. This pic kind of illustrates both, and you can see what I mean by just pulling the braid back. The vintage stuff you spotted doesn't have an outer insulator sleeve, but that is about the only difference, majorly, that I can see (besides the materials themselves).

[stringsthings]

this will probably work for you

http://www.guitarelectronics.com/product/WA5/Single-Conductor-Shielded-Circuit-Wire.html

it's from the same page as your previous post ...  foil does not normally do much in the way of shielding your audio signal from interference in a typical high-gain guitar effect ....

think of the wires carrying audio signals in the BMP like miniature guitar cables connecting amplifiers together in a miniature recording studio  ... if one or more of those "cables" picks up some sort of noise, that noise gets amplified many many times over .... this can result in oscillation .... one rule of thumb is keeping the input and output wires as separate as possible ...

in a fuzz box, the more wires leading to potentiometers and switches, the more chances for problems ... a disadvantage for the added flexibility ...

[Guitarfreak]

this will probably work for you

http://www.guitarelectronics.com/product/WA5/Single-Conductor-Shielded-Circuit-Wire.html

it's from the same page as your previous post ...  foil does not normally do much in the way of shielding your audio signal from interference in a typical high-gain guitar effect ....

think of the wires carrying audio signals in the BMP like miniature guitar cables connecting amplifiers together in a miniature recording studio  ... if one or more of those "cables" picks up some sort of noise, that noise gets amplified many many times over .... this can result in oscillation .... one rule of thumb is keeping the input and output wires as separate as possible ...

in a fuzz box, the more wires leading to potentiometers and switches, the more chances for problems ... a disadvantage for the added flexibility ...

That's what I saw as well.  I'm not quite sure the rules with wire guage, but 26 guage seems a bit thin to me.