DIY question about changing cap values in pedals

Whaaaapsh · #1 03-20-2009, 02:05 AM

I've got a DS-1 on the chopping block and I was going to do the Keeley mods, and also change the input and output cap values to:

Input cap .01 to .1
Output cap 4.7 to 10

I also use pedals for guitar, and I like to have pedals that are both bass and guitar friendly. How does changing the cap values affect the guitar-worthiness of the pedal? I figure that it's mostly bass players have made these mods, which is why I'm not posting this in the guitar section.

I can't imagine that more bass would be a bad thing for a guitar, but if anyone can comment on their experiences I'd appreciate it!

Wren and Cuff · #2 03-20-2009, 03:56 AM

You could put anything between .022uf and .22uf (or higher) and get more bass. If you want it for guitar as well, I'd go with the .1uf, still plenty of room for those bass frequencies.

Haven't cracked a DS-1 in a while, but IIRC you shouldn't have to touch the 4.7uf.

If you want to get fancy, squeeze in an SPST switch, leave the .01uf as is, run a lead from one end of the .01uf (maybe on the solder-pad side) to the switch, on the other pole of the switch run a lead to your .1uf... then the other side of that .1uf goes to the other side of the .01uf.

basically, you're using the switch to throw the .1uf in and out of parallel with the original .01uf. when the "bass boost" is on you have a .11uf, when you cut it, it goes back to "stock."

Hardest part is getting creative with fitting the switch, xtra cap, wires and making it neat and sturdy.

Or say f-it and just stick a .1uf in and call it a day.

hope this helps...

matt

B.C. · #3 03-20-2009, 09:20 AM

Quote:

Originally Posted by Wren and Cuff

You could put anything between .022uf and .22uf (or higher) and get more bass. If you want it for guitar as well, I'd go with the .1uf, still plenty of room for those bass frequencies.

Haven't cracked a DS-1 in a while, but IIRC you shouldn't have to touch the 4.7uf.

If you want to get fancy, squeeze in an SPST switch, leave the .01uf as is, run a lead from one end of the .01uf (maybe on the solder-pad side) to the switch, on the other pole of the switch run a lead to your .1uf... then the other side of that .1uf goes to the other side of the .01uf.

basically, you're using the switch to throw the .1uf in and out of parallel with the original .01uf. when the "bass boost" is on you have a .11uf, when you cut it, it goes back to "stock."

Hardest part is getting creative with fitting the switch, xtra cap, wires and making it neat and sturdy.

Or say f-it and just stick a .1uf in and call it a day.

hope this helps...

matt

+1, I agree.

I recently modded a Boss OS-2 for more bass responce(my own pedal) and threw in a switch. I used a SPDT switch to be able to switch from guitar to bass.

Brandon

rcubed · #4 03-20-2009, 09:33 AM

If the 4.7uF cap is not used in a filter (highpass, lowpass, notch, etc.) and only used as an output coupling cap, then it is plenty big. Definitely increase the input cap. With a 1uF input cap, you'll have plenty of signal to work with.

Whaaaapsh · #5 03-20-2009, 10:48 AM

Woah, sneaky solution W&C! I'll put one more switch on the shopping list, I'm going to attempt the "seeing eye mod", which also has a switch.

What kind of drill bit to you guys use to get through the enclosures? Do you use a regular bit, or one of the Unibits? Do you lube? (sorry if that's too personal

)

audienceofone · #6 03-20-2009, 10:59 AM

Where would you mount the switch?

Whaaaapsh · #7 03-20-2009, 11:02 AM

maybe next to where it says "DIST".

http://www.youtube.com/watch?v=vJWy7W6FBwA

Wren and Cuff · #8 03-20-2009, 04:37 PM

I'd say don't bother with the SEM switch. The SEM is cool, and I'd bet 99% of the time you'll have it on anyways, IIRC (might be wrong though) Keeley used to have no switch as well. He just converted it to the SEM. Again I may be wrong on this. I had one long ago, with the switch, and I never even took it off the SEM. It's a very cool mod. Gets this "spanky" thing happening in the low-end. I didn't use it much though, and sold it later for some other pedal I was lusting after, but remember it being a very fun pedal. This was also when modding pedals was a pretty "new" thing, and the blue LED was also very fresh.

I'd say, put in the "bass-boost" switch, hard-wire the SEM. BTW, if you dont care about the SEM LED being visible, it's much easier to mount the red LED on the board. It does look neat outside though.

Regarding the drill bit, pretty much any generic all-around bit will do. I've found the bit to not be that important unless you are repeatedly using it to drill through metal. Then you need a quality bit made specifically for metal. Also, no joke, spit is a great lube for drilling through metal.

good luck...

matt

nbtone · #9 03-21-2009, 12:32 AM

While you're experimenting with changing the values of the caps it's good to keep in mind that capacitors in series act in pretty much the opposite way that resistors do. ie. If you put two .47uf caps in series you get 23.5uf. If you put them in parallel you get .96uf. I don't know all the formulas off the top of my head, but sometimes the value you will find to be the most beneficial can't be found by just changing one capacitor for another.

B.C. · #10 03-21-2009, 12:33 AM

Quote:

Originally Posted by nbtone

While you're experimenting with changing the values of the caps it's good to keep in mind that capacitors in series act in pretty much the opposite way that resistors do. ie. If you put two .47uf caps in series you get 23.5uf. If you put them in parallel you get .96uf. I don't know all the formulas off the top of my head, but sometimes the value you will find to be the most beneficial can't be found by just changing one capacitor for another.

Caps in series: 1/Ctot = 1/c1 + 1/c2
Caps in parallel: Ctot = c1 + c2

Whaaaapsh · #11 03-23-2009, 12:06 PM

Quote:

I'd say don't bother with the SEM switch. The SEM is cool, and I'd bet 99% of the time you'll have it on anyways, IIRC (might be wrong though) Keeley used to have no switch as well. He just converted it to the SEM. Again I may be wrong on this. I had one long ago, with the switch, and I never even took it off the SEM. It's a very cool mod. Gets this "spanky" thing happening in the low-end. I didn't use it much though, and sold it later for some other pedal I was lusting after, but remember it being a very fun pedal. This was also when modding pedals was a pretty "new" thing, and the blue LED was also very fresh.

W&C - good to know about the SEM. I may leave out the toggle and the visible led if the microsurgery proves to be too much. btw -- damn fine looking pedals!

Quote:

Caps in series: 1/Ctot = 1/c1 + 1/c2
Caps in parallel: Ctot = c1 + c2

B.C. - I don't know what this means -- does the math still work out to the same ends (more bass)?

Wren and Cuff · #12 03-23-2009, 07:22 PM

Quote:

Caps in series: 1/Ctot = 1/c1 + 1/c2
Caps in parallel: Ctot = c1 + c2

Quote:

B.C. - I don't know what this means -- does the math still work out to the same ends (more bass)?

At this stage it's easiest just to keep it simple. Buy the right size cap. Part of this equation simply says if you run caps in parallel you just add the values. As in: .047uf + .047uf= .094uf. basically a .1uf...

Or just buy a .1uf!

I wouldn't worry about the other half of the equation yet, just see if you can do the mod solidly.

best,

matt

Whaaaapsh · #13 03-24-2009, 11:25 AM

Yeah the switch idea sounds super cool -- I'm definitely going to attempt it. The DS-1 cost me $10, so I'm really not concerned about screwing it up.

I'm thinking about picking up one of the tomes of pedal building (the Wampler book, etc) from the library to gain some deeper knowledge on electronics. I've done some BYOC builds, which were good learning experiences. Even though they're all mapped out, they always take some troubleshooting to get right. I'd love to be able to read a circuit layout diagram, but at this point in my learning curve it's really satisfying to correctly make these changes to a pedal.

Thanks for your help everyone!