madbeanpedals::forum

General => Open Discussion => Topic started by: Drew Hallenbeck on October 11, 2016, 07:44:51 PM

Title: Creating new pot values......
Post by: Drew Hallenbeck on October 11, 2016, 07:44:51 PM
So I've been thinking it would be easier to order a whole bunch of just a few values of pots then add resistors to come up with new values. This way, if I want to build something that calls for an odd value pot, I don't have to place an order and wait for a single item.

Here's something I've seen referenced here before. There are options for calculating new values for linear and tapered pots:

http://www.diystompboxes.com/analogalchemy/emh/emh.html

My question is, would this be a good idea or can anyone point out specific reasons/situations where this would be a bad idea?
Sure would be nice to just keep 2 or 3 values each for A, B and C pots then just make whatever value is called for......
Title: Re: Creating new pot values......
Post by: culturejam on October 11, 2016, 07:46:14 PM
When you do that, sometimes (often) it will change the taper of the pot in a non-good way. For example, you may end up with most of the "play" all bunched up into the first or last 1/4-turn of the wiper. Other times, it doesn't seem to make much difference. It's mostly application-dependent.
Title: Re: Creating new pot values......
Post by: Drew Hallenbeck on October 11, 2016, 07:48:10 PM
Even when adding different value resistors between 1&2 and then 2&3 like the calculation suggests for "A" pots?
Title: Re: Creating new pot values......
Post by: samhay on October 11, 2016, 08:56:10 PM
http://www.geofex.com/article_folders/potsecrets/potscret.htm
Title: Re: Creating new pot values......
Post by: stecykmi on October 12, 2016, 12:50:54 AM
Quote from: desmondtencents on October 11, 2016, 07:48:10 PM
Even when adding different value resistors between 1&2 and then 2&3 like the calculation suggests for "A" pots?

ya it will always affect the taper somewhat.

basically if the added resistors are too small compared to the pot, it will affect the taper "too much". so you can do this but you can only change the value by an order of magnitude at the most before the pot no longer behaves nicely.

most people don't use this on log-taper pots either presumably because it alters the taper.