Pots - 1. Can I Change the value? If so, how? 2. Why are specific values chosen?

[bluesman1218]

I have read several articles, including R.G.'s page, and searched the forum and haven't found this info. I think the 2 questions are related, so I'm posting them both here.

Can I Change the value? If so, how?
I want to breadboard a circuit and the only parts I don't have is are the 10K and 50K pots. I have 5K and 25K. I know I can I add a resistor to change the max value, but how can I maintain the minimum value? For example, adding a 4.7k resistor to lug 3 takes the 5k pot from 5k min to 10k max. Hope this question makes sense.

Why are specific values chosen?
Relative to the 1st question, why is a 5k spec'd out vs. a 10k? What effect does the value have?

These stem from R.G. Keen's http://www.geofex.com/FX_images/Fake%20Guitar%20Oscillator.pdf which can save a lot of time running from my garage to my 2nd floor studio/lesson room. (no, I'm not moving the bench upstairs! I'm not ready to order parts yet and I don't want to pay $3+ for pots at the shack!

[ashcat_lt]

For question 1 it really can't be done.  If your pots were too big, and you could live with a change in taper, you could put a resistor in parallel.  There is the option of using two pots in series, though. 

Question 2 depends on the circuit itself and is tough to generalize.  He says something about how the 50K pots affect the length of the note and were chosen to give a range that he liked.  He mentions changing these to taste, but doesn't explain how different values would affect things.  I don't understand that part of the circuit well enough to advise.  It certainly wouldn't hurt to try your 25K here.  It won't explode or anything.

The 10K volume pot was probably chosen to provide a reasonable output impedance.  It could be about anything and work fine as a volume control.  I suspect he chose 10K so that the circuit following would see something roughly similar to a guitar pickup's impedance.