Noob question: changing Tone pot value on 808-type pedal?

[dap9]

I noticed that one of the changes Fuller did to the OCD was change the Tone pot from a 25k to a 10k.  What would this do?  I've been searching for info on pots, but what I've found so far is a little over my head.

thanks in advance

[petemoore]

the Tone pot from a 25k to a 10k.  What would this do?
1 reduce the tonal range available with the tone control.
2 ~ the same thing as putting a 12k-15k resistor across the outside lugs of the pot, [I'd try to use clipwires on the resistor for the testing].
  }which'd reduce the resistance across the pot which would...probably *not do a whole heckuvalot but easier tried [#2] than figured out and explained.
  *Mainly it'd put the tone frequency adjustment within a smaller tonal range/more accurately ajdustable within that range.

[dap9]

the Tone pot from a 25k to a 10k.  What would this do?
1 reduce the tonal range available with the tone control.
2 ~ the same thing as putting a 12k-15k resistor across the outside lugs of the pot, [I'd try to use clipwires on the resistor for the testing].
  }which'd reduce the resistance across the pot which would...probably *not do a whole heckuvalot but easier tried [#2] than figured out and explained.
  *Mainly it'd put the tone frequency adjustment within a smaller tonal range/more accurately ajdustable within that range.

Great, thanks!  That makes sense.  The only thing that confuses me is you wrote that adding the resistor would "reduce the resistance..."  Wouldn't it increase the resistance?

thanks again!

[ayayay!]

Nope, Petemoore is correct.  When you are slapping that 15K resistor onto the lugs of the pot, you are making the pot "see" only 10K of available resistance.  You're tricking your pot into thinking it's a smaller value.   

[wampcat1]

keep in mind that the OCD isn't a TS circuit really...

bw

[bipedal]

I remembered this recent thread on TS-style tone control variations -- good discussion.  You may wish to check it out: http://www.diystompboxes.com/smfforum/index.php?topic=61984.0

Echoing a previous comment: the OCD isn't that similar to an 808 circuit...  (Perhaps you were thinking of the Fulldrive?)

Regarding resistance values:

Wiring two resistors in series would increase the resistance (R total = R1 + R2).  In contrast, wiring two resistors in parallel (as in the noted example of a resistor attached to a pot's lugs) would decrease the resistance.  See this for the equation and a parallel calculator.

Cheers,

- Jay

[dap9]

Yeah, I was aware that the OCD is based on the Voodoo Labs OD pedal and not the TS circuit.  It's just that I really like the TS circuit and it's what I've been familiarizing myself with lately.  My OCD is not gooped (I guess older versions were) so I wanted to see what similar components I could use.

Here's a link to a thread I posted a few days ago.  It has a recording I did of my GGG 808 clone w/ mods including MOSFETs and an OCD.  I did a little A/B of the two pedals w/ similar settings.  Overall, I think I got pretty close to the OCD.  The OCD still sounds better - but it is the original afterall.  But I'm trying to get the best of both worlds and I think I'm getting there.  Check it out:

http://www.diystompboxes.com/smfforum/index.php?topic=64054.0