Non-linear tone control

Discussion in 'Tele-Technical' started by 6stringelectric, May 10, 2011.

  1. 6stringelectric

    6stringelectric Tele-Meister

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    I just got a Blacktop Tele (with the two humbuckers) and I really like it.

    The only drawback is the tone control.

    It works, but almost all the action is way at the bottom.

    In other words, I can turn it back from 10 and very little happens until I get down to about 2 or 3 - at that point it is super-sensitive and very slight turning has a huge effect on the tone.

    The question is how do I correct this, so it responds more evenly through the entire rotation? The total overall effect of the tone control is fine, it just needs to be spread out more evenly if I'm making sense.

    I'll add that I do know how to operate a soldering iron, and I'm not afraid to change pots, caps, etc.

    But I'm not electronically literate enough to know what I should change, nor what values will have what sort of sonic effect.

    Thanks for any help.
     
  2. Willandthewonts

    Willandthewonts Tele-Meister

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    I'm not too informed on this subject, but I think it's a pot problem. If you throw a new high quality pot in there (500k), it ought to fix it. As far as caps, The lower the volume, the more subtle the effect the tone control will have. a .15 will roll off higher highs, and a .47 will roll off much more.
     
  3. Scott B.

    Scott B. Tele-Meister

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    I have an Affinity that came with that wonderful feature and a new CTS pot--all new wiring and switch gear, actually--solved the problem.

    I'm sorry to hear that your new guitar has that issue, it really drove me up the wall and it sounds like it's doing the same to you.
     
  4. jefrs

    jefrs Doctor of Teleocity

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    The tone control should be a logarithmic pot of 250k. If the value is too great then most of the effect is indeed at the bottom of the knob.

    The tone pot is not a potentiometer (pot) but a variable resistor (rheostat) in series with a capacitor, the inductance of the pickup is very important to the effect - it is a RLC circuit. At 250k the effect is above the register of the guitar to all practical purposes it is open circuit. The control begins to take effect at around 100k. This would be just below 5 on a linear 250k pot, or around 8 on a log 250k, lower on a log 500k. The place for using log 500k pots in in a 2+2 control circuit where they are used in parallel (also note that humbuckers have double the inductance).

    CTS and full-size Alpha pots are of similar quality. The Alpha has a slightly smaller nut thread diameter and may fit an asian import without drilling the control plate out

    A log 250k tone pot will work with all flavours of pickups. A tele normally uses a 47nF cap with it. Ultimately component choice is made by your ears, not mine.
     
  5. Bartholomew3

    Bartholomew3 Friend of Leo's

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    I have a 68 tele that did the same thing from the time it was new - and now I have humbuckers installed and it's the same.

    What I did was position the tone control knob so when the screw-hole is pointing at the sky it's gets the exact less treble sound I want.

    I better pot would fix it but not really required in my case.
     
  6. Rockhead

    Rockhead Tele-Meister

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    I would put a 500K linear pot in there. Conventional wisdom is to use Audio or "A" (non-linear) taper which is probably what you have.
    . A linear taper or "B" taper will roll the treble off smoothly from 10-1. As far as caps go since you have humbuckers use .o22uf it will roll off less high frequency. .047uf caps are for standard single coil Tele's. Humbuckers are darker sounding so you want to let more of the highs come through
     
  7. Bartholomew3

    Bartholomew3 Friend of Leo's

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    I have a PAF neck and it's still pretty bright with a .050 cap.
     
  8. frankie5fingers

    frankie5fingers Tele-Meister

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    Most certainly use a linear pot for tone (only the tone) for a smoother transition through the range. The value is, as jefs says, up to your ears. IMO, a 500 tone control with a .47 cap is pretty common, I'll assume that's because it gives you the spanky treble-y tone most associated with the Tele Twang Central. Lots of folks like a 250K though, to knock off a little of the upper freq. I've never tried the 300Ks but I'm told they are a fine compromise.
    Personally I'd buy a few decent caps (less than a buck each), maybe an .022, .027, .044, some even go all the way up to 1. Anyhow, leave all the ground leads long, and with a small drop of solder, attach the ground leads (a few are directional) of all the ones you want to try to a short section of wire. Use that as the "ground bar" for all your testers, then attach, one by one each of the other leads to the pot. It'll make the testing go faster, going from one to the other without having to hook up both legs. Faster makes comparison easier. Pick the one you like best solder it permanently and never wonder what "could have been". Remember though, the caps's effect is on the range of the tone, not the tone itself. My .002
     
  9. 6stringelectric

    6stringelectric Tele-Meister

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    I wanted to post back in case anyone else has this problem in the future.

    I had time today to open up the guitar and change the pot - the original one was a B500K so I got a Fender no-load 250K and swapped it in.

    The volume was also a B500k but it worked fine so I left it alone.

    I had to enlarge the hole in the plate a little to make it fit - but the end result is exactly what I wanted.

    It didn't change the total effect of the tone control, it still has the same amount of treble reduction when turned down all the way, and none when turned up all the way, but now the change is gradual and smooth throughout the range of the pot, much more useful.

    I may try changing caps later on, but for now I'm happy with the results.
     
  10. David Collins

    David Collins Tele-Afflicted

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    So your original pot was a linear 500k, which I would have expected to work exactly as you originally described. I'm not sure where this idea of linear taper pots for smooth tone controls came from, but it gets repeated often enough that I suppose it's worth repeating again that it's dead flat-out wrong.

    Your Fender 250k no load is an audio pot, which as clearly demonstrated in this case is a more gradual and smooth taper for tone controls.
     
  11. WilburBufferson

    WilburBufferson Tele-Afflicted

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    I am hoping some of the original respondents can help me. I am facing the exact same problem as the OP, tried his solution (swapped a 500K pot for a 250 one), but it didn't work. Here are my specs:

    Telemaster build: Seth Lover in the neck, Broadcaster in the bridge. 500K volume, 250K tone. .047 tone cap. 270K resistor from the empty lug on the bridge side of the 3-way switch (to treble up the HB).

    I find that when I roll the tone off, it's the same thing as the OP: all the action is from 3 or less, and at 0, there's no tone at all!

    Can anyone help me? I am getting to the point of wanting to tap my heels together to go back home to Kansas!
     
  12. mellecaster

    mellecaster Former Member

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    This Spec sheet was from a build I did for Forum Member Gringo13

    The Pickups are the Exact same Models you mentioned...you can see the

    Pots and Cap I used (and no resistor)...and He and I were both very

    Happy w/ the results.

    [​IMG]
     
  13. WilburBufferson

    WilburBufferson Tele-Afflicted

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    Hi Mellecaster, thanks for your reply. My broadcaster came out of the Baja Tele, so it might measure up slightly differently than the SD...

    From your specs, the only difference is the absence of a resistor, and flipping the values (more or less) of the tone and volume pots. Would this really do the trick? Is the resistor the culprit? I can't see how it can be...

    Let me ask one follow up... I am not good with the units on these caps/resistors. I see them all over TDPRI referred to as .047 and .47 almost interchagably. Maybe I've got the wrong value?
     
  14. AJBaker

    AJBaker Friend of Leo's

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    Could you please explain the reason for using 500k pots with a 2vol/2tone setup?

    I bought an Asian Explorer copy a few weeks ago, and I decided to replace all the guts with quality parts (CTS log pots). I rarely play with humbuckers, so I just put 500k everywhere. With my strats and teles I'm used to the tone control being sensitive almost all the way. Here, I couldn't hear any difference till about 6 on the knob.
    I grabbed my meter and some spare pots and started comparing values. Turns out the 500k pot measures 250k when turned to about 7-8. The section where you can hear the most effect (1~5) the value is pretty small (0.01k-80k). Sometimes just a few extra ohms make quite a difference to tone.

    End of the story, my explorer now has two 500k volume pots and a 250k tone control.

    To the OP: try swapping the 0.047uf cap for 0.022uf. That's the value usually recommended for buckers anyway.

    Mellecaster: what made you choose that tone pot for your build?
     
  15. mellecaster

    mellecaster Former Member

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    It was a New CTS 500K Pot that was that much off spec, which is pretty common I find...Worked out well though.
     
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