Now, how can we tell when we have a problem with a pot's configuration? Well, when we load down the wiper, that is where many pots generate distortion in certain positions. Which pots do and which pots don't depends on the manufacturer. You can't tell from the outside, just looking at the pot, you have to measure it, if you want to know for sure, by loading the pot's wiper and testing at a number of positions on the pot. Often it will be good until it hits a 'bad' spot. However, it could just have a short range where it just adds lower order distortion. It depends on the manufacturer.
Can it be audible? That is how we first found it.
Can it be audible? That is how we first found it.
Interestingly, the same conclusion can be found by considering circuit theory (especially potential dividers with non-linear elements). With a sufficiently light load on the wiper, it doesn't matter how bad is the contact (provided it is not open-circuit).john curl said:
I believe that some pots try to increase reliability by having several wipers wired in parallel. This actually makes the situation worse for audio volume pot purposes, as the wipers can't all be in the same place so they are sampling different points on the potential divider and then combining the result - this unavoidably depends on the quality of the contacts so a light load does not necessarily improve things.
In post 30 john Curl advised
"Cermet is not advised. Carbon, plastic or wire is".
Is it possible to expand upon why cermet is not advised?
Don
"Cermet is not advised. Carbon, plastic or wire is".
Is it possible to expand upon why cermet is not advised?
Don
Um, OK. I've used 10K log pots driven my a 100 ohm source. Load impedance generally unknown, but I assume 20K-50K. Worked very well for me. Did I do it wrong?
No sounds good to me.
100ohm> 10kohm> 20-50kohm.
Best if that amp load is 50kohm rather than 20kohm, but both will work doubt you will hear the difference.
Cheers George
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