From what I've seen the potentiometers in electric guitars tend toward the large sizes, in the sense of physical dimensions, but I don't understand why that should be. For example, wouldn't it be beneficial to strat-like designs to be able to use smaller cavities?

Again from my experience, large pots tend to be rated 0.25W, while other panel mount sizes might be 0.1W. The current from a passive pickup is almost the definition of a small signal, so wouldn't it make sense to use lower power components?

Is there an electrical reason for sticking with heavier pots, or are there other considerations?

  • Mechanical robustness is a major factor. I can't imagine there is anyone who has been playing for more than a few years without encountering at least one guitar with dodgy pots that need replacing. The other issue is when the pot is still sound but it starts rotating in its mount.... – Level River St Apr 28 '19 at 21:38
  • But if those problems are encountered with the usual pots then that's a poor reason to use them. – user1876058 Apr 29 '19 at 19:15
  • what do you suggest then? Smaller pots will get damaged even more easily! So even bigger pots? Or the same size pots of better quality? Trouble is cheap guitar makers use pots of poor quality. The other issue is standarization. All my guitars use pots with 1/4" splined shafts, so I could exchange the knobs if I wanted. The only exception is my acoustic which has a small pot in a recess in side of the body. This position protects the pot, but prevents electric guitar techniques where the pot is adjusted while playing. Also the electric bodies are too thin to accomodate a pot in this position. – Level River St Apr 29 '19 at 20:38
  • A 9mm pot can have a sturdy ¼" steel shaft. They also tend to have square bodies which could be more easily prevented from rotation. – user1876058 May 1 '19 at 8:02
  • But my point was just that listing faults failed to support the claim of mechanical robustness. – user1876058 May 1 '19 at 8:05

The main reason is that guitar technology is permanently stuck in the 1950s, when smaller potentiometers just weren't available. (I'm sure they did exist, but only in specialised military applications which would probably have cost more than the entire guitar).
In fact, for the most part, electric guitars would work much better if they included modern parts (in particular, properly designed active circuitry), but unfortunately “vintage” is the word that sells best in the world of guitars.

Large pots do have the advantage that they can be more easily soldered by inexperienced people. And they are very robust even without extra reinforced mounting or bearings. Electrically speaking, they are no better or worse than small pots of decent quality – the power rating is indeed completely irrelevant for this application.

  • Good point about soldering and mountings. I wonder if the main driver isn't economics; I suspect that if the combination of component cost and production costs were less for smaller pots, then that is what the big manufacturers would be using. – ex nihilo Apr 28 '19 at 15:59
  • I have a volume pot on one guitar that is tight - so tight it's impossible to 'violin' with. Wonder why that is like it. – Tim Apr 28 '19 at 16:02
  • @DavidBowling regardless of whether you use big pots or small ones on a single SMD board: the price is such a small fraction of the whole guitar that manufacturers won't make decisions based on that – not if any change to the status quo might drive off a significant number of the usual vintage fanatists. Pretty sure small pots would actually make the guitars slightly cheaper to manufacture, but not enough to make up for the drop in sales. – leftaroundabout Apr 28 '19 at 16:07
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    @leftaroundabout -- I doubt that most people buying guitars have any idea what the power rating of the pots is. The cost of the smaller component might be cheaper, but this could be offset by other factors; in a production setting less error-prone installation of the pots would be a significant cost factor. – ex nihilo Apr 28 '19 at 16:16
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    @DavidBowling of course the buyers wouldn't have any idea about the power rating. Or anything else, for that matter. But the salespersons in the guitar shops would know that that guitar has eekie modern tiny pots, and tell some nonsense about that this sounds “colder and thinner” than the good old ¼W ones to customers who ask. In particular if the guitar with the small pots is a bit cheaper. – leftaroundabout Apr 28 '19 at 16:21

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