Opinions on pot values

[Weldaar]

I have been using 300K pots in my bridge for 20 years, but now I use a darker amp (Fuchs Blackjack 21 MKII) What is your opinions on the use of 300K pots vs 500K pots?

[tedmich]

500k should let more treble through, you might like it! Single coils or HBs?

[Mark Hammer]

Pot values matter, and accomplish everything people say they do, when you tend to leave the volume up full most of the time. If you are a player that tends to monkey around with level, the moment you turn the volume down from max, you forfeit the "unloading" that higher-value pots provide. The reason is that the loading or unloading is a property of the resistance-to-ground from the volume pot wiper, relative to the resistance to ground from the wiper through the pickup, Once you turn the volume down even a small bit, you have placed some of that pot resistance in series with the pickup, such that what the amp "sees" is, for example, 450k to ground (through the pot), and 58k to ground (pot portion + pickup).

[Chuck H]

You can always try it and see for yourself. Higher value pots will be brighter, up to some extreme. Even hot singles shouldn't be significantly brighter beyond 500k. 1M for hot humbuckers. And like Mark said, if you play with the volume control less that full up there's no real advantage to the higher values.

Ok... Now... If the amp is lacking in harmonics or seems to lack attack and definition then brightening up your guitar might help. If all that stuff is there but the overall EQ lacks treble you might do better to consider different speakers.

If you have other amps you'll use from time to time with the same guitars and speakers things get more complicated. If you change your guitar or speakers the other amps tone won't be what you're familiar with anymore. This is obviously something you need to work out for yourself, but if "I" already had a program in place that I liked I probably wouldn't change it to suit one new purchase. I'd change that new purchase to fit my program. I really like Andy's amps. They have a saturated quality to the distortion that I like. It's not the gritty, brash, spikey Marshall sound (though I like that too). I only mention it because if you wanted this new thing to sound like your old thing you might have considered more carefully before making the change.