Lowering Pot value with resistor

[mauiboy81]

Hi guys,

I have a Marshall JCM 900 that needed new pots. I didn't want to spend $5 a pot so I bought the 16mm long shaft pc mount alpha pots from Mojo for just over a buck each.

There were two values that they didn't have, 22k and 220k, but they did have 25k and 250k so I bought them. I got them and one is in the 220k range, a couple are in the 230-240k range and the other in the 240k-250k range.

So can I use them as is?

or

Should I add a resistor across outside lugs of the pot to drop the value to what I need? or will this cause problems?

Thanks for your help

Nick

[M Fowler]

mauiboy81

You can use as is.

Mark

[Phil_S]

Adding a resistor changes the taper and you don't want this. What Mark says, use them as-is. You won't notice the difference, except, of course, whatever was broken will work.

[mauiboy81]

Thanks guys.

They were all really scratchy and a few had been hit and bent and the back casing had come off.

It'll be nice to have them working again.

Thanks again

Nick

[Andy Le Blanc]

Here's what happens with the taper of a pot. when you modify them with resistors.

[Firestorm]

On this topic, here's a nifty article from R.G. Keen:

http://www.geofex.com/article_folders/p ... tscret.htm

[tubeswell]

Those log and antilog tapering resistors can also be used to increase the taper of existing Audio (and Reverse Audio) Pots. This can help improve the 'two-line-taper' characteristic of modern off-the-shelf pots, but at the expense of lowering overall resistance one way or the other (hence you might want to try this with pots that are 2 x the value required), as well as adding a proportional amount of series resistance on the 'other' side of the wiper.

[Kregg]

While we're on the subject. I've seen some folks add a trimmer pot; in one case the guy used a trimmer to bring a 1M pot down to 700K.
Does this method work any differently than using a resistor?