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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!

  • Are you sure what you think is a tone knob has not been modified to be a kill switch? – Neil Meyer Nov 22 '15 at 15:24
  • It seems unlikely if only because it only kills the higher frequencies. I've given up using it - tone is always 'on', though maybe I should be making use of this sound in some way! – Mr. Boy Nov 22 '15 at 21:12
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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.

  • It jumps very suddenly and then remains constant - the wiper losing contact should still show some variance when it is in contact right? How would I determine what kind of pot I should use? – Mr. Boy Jan 7 '15 at 10:46
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    Best bet would be to try replacing with the same kind of pot is has on there at the moment. There will probably be a serial no. on the pot or some gubbins which tells you what kind. You can probably get a new one from somewhere like Maplin (or Radio Shack? Are they still going?). Alternatively this site might help re what kind to buy : diyguitarmods.com/potentiometer.php – user2808054 Jan 7 '15 at 12:51
  • Note that it could be the capacitor also, but most likely the pot as it has moving parts. That site I linked to has info about wiring tone pots too. – user2808054 Jan 7 '15 at 12:53
  • If the wiper is fine but the track is broken, it might do this. Basically, it becomes a switch with variable impedance when on, but if that impedance is negligible to the rest of the circuit without the other connection, you wouldn't hear a difference except for the switch. – AaronD Jan 7 '15 at 15:57
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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%.

  • It goes from "watery" - which I'm happy to believe is correct - to very bright as if I had a switch rather than a knob. I can't say for definite it's not doing anything the other 90% of the knob travel but I cannot hear it at all; by contrast on my old cheap Encore Strat-copy I can clearly hear the tone knob doing something. It sounds very much like the full tone range is happening in a tiny fraction of the knob's travel. – Mr. Boy Jan 7 '15 at 15:51
  • Hmmm, OK there must be a problem. I think the only solution to this would be to change the electronics as the tone knob is just a potentiometer. If you change the potentiometer to one that does not change value as steeply it would solve the problem. I can't say much more without seeing the guitar along with an oscilloscope. – texasflood Jan 7 '15 at 16:17
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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.

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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.

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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.

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