Mods to Pepper Spray?

[Natman]

Hi all, I like my pepper spray a lot. However I think I could get a little more flexibility out of it. Here is what I am thinking:

1) The gain control is pretty useless.Guitar volme is all that's needed if I want to clean it up, so I'm planning to ditch it.

2) A tone control might do well to help give more range, and based on the Catalinbread Karma Suture, I think they implement an input cap blend knob much like a DAM Red Rooster. I have a Red Rooster clone and it is an extremely effective knob to tailor the sound. In fact, with no clipping diodes, the Pepper Spray sounds pretty much like a good germanium clean boost.

3) A clipping blend knob would be great, and again I think CBread did exactly this. However, I'm not sure what value pot to use.   

4) I'd like more volume from the 1N695 setting. I can't think how to do this, but was planning to put a boost after it (probably Sunking) in the same enclosure. 

What are some mods you have done or know about?

I saw this guy, seems interesting:
http://www.diystompboxes.com/smfforum/index.php?topic=104404.0

On a side note, I started off thinking the diode switch was kind of useless. I even bought 2 (Very) expensive OA126's for the second slot. Overall, I liked the stock configuration best. Yeah, it was the most quiet and pretty compressed, but I wanted more fuzz than overdrive and this setting gave me that sound. THEN I tried different guitars and realized how much the pickups matter. IMO, the toggle switch will let you adjust the compression level for the type of guitar (singles, P90, humbuckers). 

[midwayfair]

1) It's not useless when you use higher Fv diodes! Removing this might do other things to the sound of the pedal -- it will change the pickup loading. In other words, you might want to replace it with a 100K (to ground) and a 1K in series with the input to mimic having the pot being in the circuit and turned down 1%. This will help prevent popping and will ensure proper pickup loading.

3) Use a 25K, in series with or as a replacement for the entire switch (so it will affect both diodes). A 10K will do in a pinch and you can use 50KC as well. It really depends on how close you want to get to the diodes being lifted. Remember that this works like a clean blend -- it's limiting current through the diodes, not just decreasing the voltage that passes through them, so it's not identical to raising the Fv of the diodes. (Not that the end result is terribly different ... but it CAN be, just like that resistor in series with one of the 1N695s might sound different from it just being another diode.) Like any other control dumping signal to ground, you most likely want to use a logarythmic taper instead of a linear, so C or A depending on whether you want "less" or "more" as the control is turned clockwise.

4) Whatever boost you use, pick something with good fidelity and minimal or no treble cut. You might end up with some issues amplifying noise when adding a boost, though. The problem is that if you correct the noise by cutting treble, you lose the harmonics that make this pedal special. This is really one pedal that seems to sound more magical going straight into an amp than it does with anything following it.

[Natman]

Jon, you are a nut. I mean that in the best way possible! You're usually the first person to respond when I ask a question and you invariably have something useful to offer. Are you being paid by Madbean? Regardless, I'm really grateful that you volunteer your know-how.     

Re. #2, will this pot be affecting the pickup loading since it's right after the gain pot? 

After all of this I could have just bought a Karma Suture, but I love these little projects!

[midwayfair]

Re. #2, will this pot be affecting the pickup loading since it's right after the gain pot?

Not exactly. Short answer: Your pot will block lower frequencies more as the bass is tuned out, but higher frequencies will be lossless.

Longer answer:

The load the pickup drives is determined by the impedance of the following stage (which is at the base of the first transistor ... note that it's WAY down there anyway from the base resistance!).

The input cap blend is just variable capacitance, forming a high-pass filter with the input impedance of the first transistor. Use a calculator if you want to figure out good cap values for it: http://sim.okawa-denshi.jp/en/CRhikeisan.htm

A capactitor acts as a short for frequencies above a circuit point (which is ALWAYS determined by a resistor, even if you don't see an obvious one!), and they block DC. As the capacitance goes down, frequencies below a certain point start to look/act like DC to the cap, so it blocks them. If you put a resistor in series with a capacitor, it will impede ALL frequencies. If you put a resistor in series with a capacitor, and both of them in parallel with another capacitor, the capacitors will try to add their capacitance together, but the resistor will impede some of the lower frequencies. As the resistance goes up, more of those low frequencies passed by the larger capacitor will become blocked, while the higher frequencies continue on their merry way as usual. As the resistance goes down, the resistance will block less of those low frequencies, until the resistance reaches 0 and the capacitors will pass everything above their lowest point. (Caps add in parallel).