Why does my tone knob seem to act as an on/off switch and what should I do about it?

Question

I have a mid-90s Washburn MG-40 electric guitar. It was very crackly when I acquired it so I took it to be serviced.

I'm new to playing electric so the tone knob is a bit of a mystery to me, but mine is surely a bit odd - it's effectively only got two settings. Turned all the way down, I get a very muted "underwater" sound. Turn it a little and suddenly it goes to a "normal" sound. That's about 10% of the travel of the knob - the remaining almost full turn makes no discernable difference to the sound.

I assume this is a problem rather than a feature but I'm not sure quite what it means or what to do. It seems an odd fault for a potentiometer to develop to me!

Answer 1

Well, "tone" is basically just a pot and a capacitor. Either can be broken, or there can be a mismatch to the pickup (if the pickup is not the original one). If "suddenly" is indeed a jump in tone quality at 10%, then the pot is likely broken, with the wiper losing contact with the track at this angle. You might or might not have success with pot spray.

If it is just that the tone difference is compacted into a too small angle range, this can be a problem with the capacitor, or it may be that the pot has been replaced with a wrong value or a wrong characteristic (there is linear, logarithmic, and reverse logarithmic) compared to the original.

Answer 2

My guess is that there isn't something that wrong with the knob, you just can't really hear the difference. 10% is a bit extreme though, maybe the capacitor/resistor combination needs changing. Does the guitar sound very bright with the tone on full or is it still 'underwatery'? (It is supposed to sound underwatery with the tone knob all the way down by the way).

Try strumming the strings close to the bridge and try playing harmonics/high notes and then play with the tone knob, you should hear more of a difference and the sound should change past 10%.

Answer 3

A variable resistor ("potentiometer") may have its track broken at the point where the sound suddenly changes from "full off" to "full on". Any workshop with even basic electronic repair tools can determine this very easily.

It is difficult to say for sure without seeing a wiring diagram but may be worth checking.

Answer 4

I bought a brand new schecter solo II. Came in the original packaging and everything from GC.

its tone knob acts exactly the same way. In fact, the volume knobs act exactly the same. If both PUs are selected, and you put one volume knob at 0, your entire guitar is muted, even if the other knob is on 10.

It gets even better. When you play with the volume knobs, you will also notice on this guitar I have, that both knobs must be EQUAL in value or you'll get a constant tone.

Lets say you set both at 10. If you set the bridge or neck PU to 8, and you do this SLOW, you'll hear nothing, nothing, nothing SUDDEN CHANGE. And then after that, you won't hear any tonal difference whether its 10 and 8 on each PU or 10 and 6, 10 and 4, 10 and 2.. until you hit 10 and 0 then you get the nice mute.

I reckon that the tone control AND the volume control issue have to do with basic passive electrical behavior.

Same thing happens on my rickenbacker bass with those volume knobs.

The short answer is: This is probably exactly how the knob 'should' behave. There is likely absolutely nothing at all wrong with the pot or the bypass cap.

Answer 5

It is not broken. Got the same in my Ibanez GIO. Its pretty common in cheap guitars. You have to replace tone circuit(its potentiometer and capacitor) if you need it more functional.