Adjust potentiometer values using resistors?

[rudeez]

Sooo! Im in desperate need for 22K REV LOG pots aswell as 4.7K LOG pot. These seems hard to find unfortunately..
I got a tip from a "local" diy supplier, he couldnt get hold of these either.
He gave me this link http://www.geofex.com/article_folders/potsecrets/potscret.htm and told me that it's possible to use like a 25K REV LOG and modify it with a resistor to get it working like a 22K REV LOG, same with the 4.7K LOG.
Im to stupid to understand this since im quite green on everything that has to do with building pedals from scratch. My experience is with other DIY related stuff, just recently built my first booster, other then that only modified pedals.
Just orderd stuff to build 3 diffrent pedals which includes a OCD clone, Bif Muff clone and the one i need pots for, the TC Integrated preamp.
Check the vero layout for it here: http://www.aronnelson.com/gallery/main.php/v/slackers-stuff/tcpreboardfinal.jpg.html
I would be very thankful if anyone could point me in the right direction here.

Kind Regards
Jimmie, Vildhjarta

[DavenPaget]

A 25K and 5K reverse pot is alright .
But it looks like it's hard to find too . 

[rudeez]

Did you check the vero layout?
Are you really sure that i can just pop in a 25K and 5K without it having consequences and impact on the sound?

[slacker]

Because of the way the pots are wired using all 3 lugs I don't think you can modify them with resistors to make them reverse log. For P3, the 4k7 log you can use a bigger value without any problems, there's another version of the TC Pre that uses a 47k/50k log pot.
You could try linear 22k pots for the bass and treble, the circuit will work fine, but the "feel" of the controls might be a bit strange, it will sound the same though.

[LucifersTrip]

5's:
http://uraltone.com/kauppa/product_info.php?info=p2203_Alpha-5K-REVERSE-LOG---16mm--mini-pot-.html&XTCsid=80i4s7m1pq7oacqdtmbhtbk4u0

25's:
http://www.ebay.com/itm/CTS-15-16-25K-REVERSE-LOG-CONTROLS-PC-TERMINAL-Lot-10-/320788413710?pt=LH_DefaultDomain_0&hash=item4ab07abd0e

[rudeez]

Because of the way the pots are wired using all 3 lugs I don't think you can modify them with resistors to make them reverse log. For P3, the 4k7 log you can use a bigger value without any problems, there's another version of the TC Pre that uses a 47k/50k log pot.
You could try linear 22k pots for the bass and treble, the circuit will work fine, but the "feel" of the controls might be a bit strange, it will sound the same though.

thanks for your answer! but i think you got me wrong, lets say that i find a 50k rev log pot, can i adjust that to 22k using resistors? as for the 4.7k normal log pot, i found that one by now but i guess a 5k would work as well?
the scheme with 47k/50k, it's the same as the one that i use, only diffrence is that i have to switch other components if i wanna use those. but if i switch those components to make it use 47k rev log, would a 50k rev log work just as good?
also, what do you mean with the pots going to have a "strange" feel to them if using normal non reverse pots?

[PRR]

If that build is truly based on this schematic, then IMHO the tone pots P1 P2 should be normal Audio Taper, NOT reverse. i.e. the parts-list is wrong.

The "Secret Life" tricks will not turn "any pot into any other pot". It specifically applies to simple Potentiometers such as used for volume controls. It can not make a 2-wire reverse-audio reostat. It would gum-up a complex tone-control which has other parts where the "taper" resistors would go.

If unsure, build with Linear. It will work. Worst can happen is all the action is cramped into part of the rotation.

[Scruffie]

A 25K and 5K reverse pot is alright .

Yup, 22k & 4k7 are just the english (european?) standard, in America you get 25k & 5k, they're all close enough in value (especially with that 10% pot tollerance).

[rudeez]

If that build is truly based on this schematic, then IMHO the tone pots P1 P2 should be normal Audio Taper, NOT reverse. i.e. the parts-list is wrong.

The "Secret Life" tricks will not turn "any pot into any other pot". It specifically applies to simple Potentiometers such as used for volume controls. It can not make a 2-wire reverse-audio reostat. It would gum-up a complex tone-control which has other parts where the "taper" resistors would go.

If unsure, build with Linear. It will work. Worst can happen is all the action is cramped into part of the rotation.

Are you sure about this? Why does the scheme says 22k neg log then? :/
Im really confused here.

[DavenPaget]

If that build is truly based on this schematic, then IMHO the tone pots P1 P2 should be normal Audio Taper, NOT reverse. i.e. the parts-list is wrong.

The "Secret Life" tricks will not turn "any pot into any other pot". It specifically applies to simple Potentiometers such as used for volume controls. It can not make a 2-wire reverse-audio reostat. It would gum-up a complex tone-control which has other parts where the "taper" resistors would go.

If unsure, build with Linear. It will work. Worst can happen is all the action is cramped into part of the rotation.

Are you sure about this? Why does the scheme says 22k neg log then? :/
Im really confused here.

Fixed . Blur no more .

[rudeez]

Okay, so just to make things clear here.
I can use 22K LINEAR pots as well as a 4.7K LINEAR with the cons of it beeing the curve will be diffrent? and no loss in values and sound?
Or should i use 22K LOG and 4.7K LOG?
I read this one http://www.beavisaudio.com/techpages/Pots/ but still can't wrap my head around it really... Takes time and practical testing to understand i guess..

[DavenPaget]

We tell you , honestly , 25K and 5K audio log will do , ( or 22K and 4.7K european standard )
IF unsure , build with linear .

[deadastronaut]

i had a similar request....this mayor may not help, but it helped me..many thanks to Gurner!..

http://www.diystompboxes.com/smfforum/index.php?topic=90097.0

[DavenPaget]

i had a similar request....this mayor may not help, but it helped me..many thanks to Gurner!..

http://www.diystompboxes.com/smfforum/index.php?topic=90097.0

But but ... it only works for pots wired as variable resistors .

[rudeez]

thanks for all the replys! i know im quite lost but im for sure learning, isnt that what forums are for?
i actually got the 10pcs of used 25k rev log pots from ebay yesterday, or maybe they were just old.
but i will also order some normal log 22k and try them out, i guess that if i try the diffrent ones i will se the diffrence between them in usage.
i will come back with the results and the build as soon as i get all the components for it.
had to get the zero ohm resistor from ebay couse i couldnt find them anywhere in sweden for some stupid reason.
atleast im getting the box today and can start doing graphics and plan out the drilling etc.
will go inside a normal mxr size box. updates will come!

[DavenPaget]

Get the 25K audio log instead of the 22k if it's cheaper . At least .

[slacker]

had to get the zero ohm resistor from ebay couse i couldnt find them anywhere in sweden for some stupid reason.

For the zero Ohm resistor you can just use a piece of wire, that's all a zero Ohm resistor is.

I'll be interested to see what you find out about the pots, I've seen two versions of the schematic and they both specify reverse log pots, but Paul knows what he's talking about so if he says they should be Log he's probably right.