Help With Pots - 22k Lin / 25k Lin

[Catsworth]

Hi Guys,

First post here so first of all some serious thanks are in order.  Thanks to everybody that contributes here, and thanks to Aron for maintaining such a great site

Ok, down to business then.

I'm looking at a shopping list at the moment which includes a 25k Lin pot.  The nearest I can get to this is a 22k Lin pot, will this make much difference?

The schematic is a Tonepad one, and it's here: http://tonepad.com/getFile.asp?id=75

Thanks for the help.

*Cats*

[Catsworth]

Oh yeah.....and while I think about it.....what type of capacitors should I be buying?

Thanks again

[tcobretti]

The 22k pot will reduce the amount you can turn the tone down.  It will sound the same wide open as it would with the correct pot, but will sound different when turned down all the way.  If you solder a 3k resistor between the pcb and lug 1 of your 22k pot it should act the same as a 25k pot (Right?  I always screw that up.).  If you leave out the resistor and use a 22k pot I supect it won't make too much of a difference.

If you haven't, you should read:
http://www.geofex.com/Article_Folders/potsecrets/potscret.htm

People say that the type of cap changes the sound, but it is extremely subtle.  Use the correct value of any type and you'll be golden.  Note:  When you buy electrolytics, be sure to buy low voltage for stompbox use - they are generally cheaper and take up less space.

[Catsworth]

Thanks for that, I'll make sure I've got a resistor I can use inline with the pot.

As for Caps, would these be suitable:

100 = http://www.maplin.co.uk/module.aspx?TabID=1&criteria=Electrolytics&ModuleNo=7011&doy=2m6 (it's 10v though, not 16v - is that ok?)

0.01 = http://www.maplin.co.uk/module.aspx?TabID=1&criteria=0.01&ModuleNo=371&doy=2m6

0.1 = http://www.maplin.co.uk/Search.aspx?criteria=WW21X&DOY=2m6

47 = http://www.maplin.co.uk/Search.aspx?criteria=WX52G&DOY=2m6

Cheers

[Gilles C]

I would also just add a 2.7K resistor for example in series just to try it first, and then use my ears to check if I would notice a difference when I would short the resistor. Then you will know for sure if you can just leave that resistor out. That's the best way to try a circuit when you don't have exactly the right parts.

But check this part list from J.D. for that pot...  http://www.generalguitargadgets.com/pdf/ggg_bluesbreaker.pdf


Gilles

[Catsworth]

Ok, so it doesn't look like the 22k pot is too much of a problem then.....that's good


Why is it that we Brits insist on having totally different measurements etc to everybody else in the known universe?  Who would have thought that finding a TL072 IC would be so hard?
It looks like that's the only component that Maplins don't do so I'll have to order that one piece from somewhere else

Sorry this is turning into an epic guys, it's my first pedal and I want to make sure I'm buying the right bits before I go spending money all over the place.

Thanks for all your help so far

[tcobretti]

You can use film or ceramic caps if the values are correct, so either of those should work.  For the electrolytic, I would use radial instead of axial (you can see the difference in the pics).

http://www.maplin.co.uk/Module.aspx?ModuleNo=13472&&source=14&doy=2m6

[Catsworth]

Cool, thanks for that