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Post by 009 on Jul 3, 2022 20:18:03 GMT -5
I finally got around to replacing the harness in one of my guitars. The tone pots are 500 k (CTS, 5% tolerance), which are "spec" for this guitar (as are the tone caps/0.047 uF and volume pots/250 k). Anyway--for both tone pots--all it takes is about 1/10 knob rotation from minimal treble to sudden, intense treble. Is there anything, short of replacing the pots, that I can do to change that terrible audio curve?
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pdf64
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Post by pdf64 on Jul 4, 2022 5:50:16 GMT -5
If they’re audio taper, that’s weird. Have you got a meter, a basic one is fine.
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009
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Post by 009 on Jul 4, 2022 6:42:34 GMT -5
Yeah, I’ve got a meter and I’ve been using it a lot during the past two or three weeks on a few guitars. After watching some YouTube videos, I concluded that I could measure components as they are wired in place, but learned that that isn’t true. The pots can sort of be measured—not their absolute resistive range, but rather relatively speaking, noting the relative ohms as you turn the control full range. Am I correct on this? Well, I forgot to measure the output of the pickups (getting old), so disconnecting that harness may be something I would probably do, anyway. My soldering skills are improving, too, so disconnecting the pots won’t be that big a deal. What do you suggest? It would be a neat trick if you could alter the hockey stick profile of these pots. I’m wondering if changing the pot input (via cap) to the opposite leg of the pot would not only reverse the basic tone control, but also reverse the output characteristics: instead of minimal or no bass and at least 90% definitive treble comprising the pot’s range, if by reversing the connection you would have those characteristics reversed, also — to 90% bass with only 10% now treble.
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pdf64
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Post by pdf64 on Jul 4, 2022 6:51:43 GMT -5
With the standard wiring, tone pots can be measured in circuit.
Just set the knob to the middle (so 5 on a typical 0-10 knob), set your meter to resistance and touch one probe to one end lug, the other to the other. Note the reading.
Then move one probe to the middle lug. Note the reading.
Then move the probes so the one is on the middle lug, the other is on the other end lug, and take the reading.
So 3 readings total.
Those will tell the basic pot tapers.
To go much further, the wiring diagram that’s been used is needed (or good photos).
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Post by funkykikuchiyo on Jul 4, 2022 14:18:08 GMT -5
There are such a thing as a reverse audio taper, meant for lefties who like to wire their controls backwards from righties. That can give a really wonky taper. That doesn't seem like a likely mix up, though.
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009
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Post by 009 on Jul 5, 2022 21:37:49 GMT -5
Since a slight rotation seemed to change things rapidly, I measured both pot resistances as they were wired up--in reverse. I wrote down all pot terminal readings at every 1/8 functional rotation. Tonight I moved the tone cap wires to the opposite terminals to get a "normal" or "typical" control rotation function and measured all of those things again. I was hoping, sort of, to see some difference in these resistance readings, but both pots at both functional rotations seem pretty much the same. When I tried the tone controls on the guitar, the sudden jump from bass to treble was not quite as great. I think there is a problem with solder connection for the neck pot -- can't hear any change throughout its entire rotation. Here's the info. I hope you can read it. I'm trying to post/paste a pure link: Resistance analysis/profile of CTS pots
Those "1-3" and "1-2" and "2-3" numbers are the terminal numbers measured across. |
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gbfun
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Post by gbfun on Jul 6, 2022 4:15:40 GMT -5
Hmm...this sounds like what I went through ! I don't have answers exactly, just observations.
1) When a pot I just soldered doesn't change through it's entire rotation...it's dead from too much heat in soldering.
2) I have two practice guitars that sound just right with the tone at minimum(I have to reduce the Vol to 9 on one), and when I turn up the tone, there is WAY too much treble. In short, the tone range is wider for the treble range...probably as designed. But with my settings, that treble is almost totally unusable for practice distorted tones. I suspect this treble is more useable with dramatically different EQ settings, tube amps, full band practice and performances etc. But for practice where I need solid distortion rhythm and ear-candy lead on non-pro equipment, it works ok for me. And as a hint for you, when I go to clean rhythm, I max the tone for a workable clean. Not perfect but it all works for me...for now.
The unanswered question is : the volume and tone design was a good idea to SOMEBODY who hopefully was pretty good. But for what amp, what settings, and what style of music ? People say how guitars have enough range for any type of music, but I don't think that's very true for discriminating players. Some guitars just sound good for specific sounds I think, and your guitar sounds like it's designed like my practice guitars. Mine are Korean with humbuckers and I think they are definitely midrange rock guitars. And they just barely get where I want to go with non-pro equipment .
My next gamble might be to change out the taper pots for straight line pots someday. If you don't get what you want, you might try this yourself.
Good luck !
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gbfun
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Post by gbfun on Jul 6, 2022 4:44:28 GMT -5
Hmm...perhaps our super bright tone pots mean that our guitars are actually short necked BASSES !?
LOL
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Post by ninworks on Jul 6, 2022 5:16:47 GMT -5
I had a similar problem with the tone pot in my Strat after getting it back from a tech who changed the cap on it. It was wired backwards. After I reversed the positive and negative wires on the tone pot the problem was fixed.
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009
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Post by 009 on Jul 6, 2022 6:45:15 GMT -5
gbfun: My first thought was that I fried the cap; those (any) wire heats up pretty quickly. I might have stayed a little too long on that connection to the pot. What are the symptoms of a fried cap? One YouTube guy said you really don't have to worry about overheating a cap.... But, it could be the pot, BUT I did get a full and seemingly accurate range of resistance readings after switching connections; this is why I think it's either a poor solder joint or a bad cap. I think I have nothing to lose by reworking that cap-pot solder connection.
ninworks: I bought this harness pre-assembled; I did not notice any polarity markings on the caps (Sozo, 0.047 uF), but I'll check again today when I'm back in the guitar checking joints (and continuity of everything).
(PS - Once you edit a quote [e.g., deleting non-relevant portions of the quote], you cannot keep your own new text from jumping into that quote box. I'd had to avoid using the quote function.)
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pdf64
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Post by pdf64 on Jul 6, 2022 7:16:38 GMT -5
… Here's the info. I hope you can read it. I'm trying to post/paste a pure link: Resistance analysis/profile of CTS pots
Those "1-3" and "1-2" and "2-3" numbers are the terminal numbers measured across. Good work! Unfortunately (!) it all looks fine, on the basis of that info, your tone controls should be working like they should, full clockwise should be brightest, full CCW should be dullest. Dunno what to suggest next, sorry. |
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009
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Post by 009 on Jul 6, 2022 7:55:19 GMT -5
pdf64 -- Thanks for looking and advising. I'll rule out the solder connection (and hopefully, the cap) later. The tone change--even at extreme ends of the tone pot--may be subtle, as in, "my hearing is shot and I can't hear a thing." I watched/listened to a couple of YouTube videos comparing various cap specs in real time as they were connected (with clips/jumper) to a guitar while the OP played a series of notes/chords. On one video, I could not hear any difference (I think the four different caps ranged from .022 to .047...?). On a similar video, I could hear a *slight* incremental increase of bass response as the cap values went up. Well, I'll have to keep my hearing in mind, although adjustment of the bridge pickup yields distinct changes; often "too brittle."
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pdf64
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Post by pdf64 on Jul 6, 2022 9:06:27 GMT -5
Just to note that turning the tone to minimum (CCW) doesn’t normally increase bass response per se. Rather it rolls off treble and causes a slight resonant boost in the mid range. Somewhat akin to a wah set heel down. The value of the cap (together with the inductance etc of the pickup) determines the particular frequency of the midrange resonance and high frequency roll off. This is a good document which explains the technical stuff behind the above. Apologies that it may go a bit deep, but the charts may help to visualise what’s going on. buildyourguitar.com/resources/lemme/ |
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Post by Leftee on Jul 6, 2022 9:33:11 GMT -5
Rather it rolls off treble and causes a slight resonant boost in the mid range. Somewhat akin to a wah set heel down. I purposely set up Tele pickups in a way to achieve this. I use a .015uF cap wired '50s style in between the 250k pots. It yields a lovely "Chickened-wah" in many cases as the tone is turned back. It also makes more the the tone pot's sweep useful. |
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009
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Post by 009 on Jul 6, 2022 12:37:32 GMT -5
I just spent a half hour with my multimeter and this harness. All points/components are grounded; solder joints seem to have good "continuity." The weird thing is that I can consistently get 46.96 nF readings of the 47 nF (0.047 uF)cap connected to my neck tone pot (this is the one I'm concerned with), but I can't get anything anywhere from the bridge cap, which seems to be the one working (notable treble change upon pot control rotation); just readouts that are all over the place; I suppose the most often readout is 12.24 nF, but there is no consistent readout on the "good" / bridge pot.
In a way I'm tempted to replace the cap on the bridge pot, but why? if the control seems to work? On the other hand, I'm tempted to just get some new pots and caps (I have a spare switch) and just build my own harness; Bourns pots and Sprague caps.
Observation: I've been screwing around with this stuff (multiple guitars) for a while. A couple of weeks ago I was starting to grow weary of it all. I picked up my then neglected Taylor GS mini; at that moment it seemed like I was in Guitar Nirvana. It seemed like pure tone; no psychological need to screw with any knobs, subconsciously asking, "Can you hear me now? How's this sound? How about now? Now, how about this setting? Wait, let me turn the volume up. What do you hear now? How's that? How's this? Hmm... Crap!"... ad infinitum....
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Post by Leftee on Jul 6, 2022 13:48:00 GMT -5
It’s still a handy journey to take. You know, from experience, what you like.
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Post by LTB on Jul 6, 2022 16:56:49 GMT -5
gbfun: My first thought was that I fried the cap; those (any) wire heats up pretty quickly. I might have stayed a little too long on that connection to the pot. What are the symptoms of a fried cap? One YouTube guy said you really don't have to worry about overheating a cap.... But, it could be the pot, BUT I did get a full and seemingly accurate range of resistance readings after switching connections; this is why I think it's either a poor solder joint or a bad cap. I think I have nothing to lose by reworking that cap-pot solder connection. ninworks: I bought this harness pre-assembled; I did not notice any polarity markings on the caps (Sozo, 0.047 uF), but I'll check again today when I'm back in the guitar checking joints (and continuity of everything). (PS - Once you edit a quote [e.g., deleting non-relevant portions of the quote], you cannot keep your own new text from jumping into that quote box. I'd had to avoid using the quote function.) Suggest using a pair of hemostats to clip on the wire lugs of the pot as close to the body as possible which will serve the purpose of a heat sink (or alligator clips) and also on the capacitor near the cap's body itself so you don't sap the soldering iron's heat. When soldering to the back of the pot I use a 60-80 watt iron so solder quickly heats and wicks onto the back of the pot. Get on and off as quick as possible. For everything else no more than 25-30 watts. |
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009
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Post by 009 on Jul 6, 2022 21:17:22 GMT -5
Interesting aside: A couple of weeks ago I'm trying figure out why the neck tone control had no effect at all on a different guitar. I examined and measured components, checked continuity, and was still at a loss. Then I plugged another guitar in my combo amp and had the same problem! Checked the cords; all OK. Pulled out my trusty Gibson Skylark amp and then I found my tones. The defective amp worked, although the max volume was diminished....
So, with this problem I'm having now I can certainly rule out a defective amp. I only play at soft volumes in my room. Out of some sort of subconscious desperation I turn up the guitar's neck PU volume to max. There I finally got the treble control I was searching for. I turned the amp's volume down and did some experimenting and am finding that there is a tremendous degree of functional interaction between respective volumes and tones/their respective controls. The bridge PU seemed to have a little less volume compared to the neck PU, so I raised the bridge PU up slightly; seemed to help. The most mysterious thing is that when I have both switched on, the tone control for the bridge pickup does not work at all. When the bridge PU is selected by itself, no problem. If the neck PU is selected by itself, no problem. If both PUs are selected, only the neck tone control works. The neck tone control only works if the guitar volume is cranked up. The bridge tone control seems to work at any volume if it is selected alone.
So I've heard of harness designs where resistors, etc. (sort of like what Leftee mentioned) where it is possible to minimize or eliminate these sorts of unwanted interactions; I'm not sure, as I don't really lose any volume of any PU, just can't get the tone pots to work right.
Every time I get stuck in one of these situations, I grow more and more appreciative of the Telecaster design: just two knobs and a switch. When my Danelectro's switch died, I couldn't figure out the pin outs/connections of a new "box'like" switch, so I installed a telecaster type, and replaced those stacked dual action pots with regular single action pots. Simplicity is so good.
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Wrnchbndr
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Post by Wrnchbndr on Jul 12, 2022 23:00:43 GMT -5
Quite unusual to have 250K volume and 500K tone pots. But a designer may do this to maximize treble response from the pickups if they were prone to being muddy with a pair of 250K pots. A standard tone pot rotated fully CCW would essentially be 0(zero)K ohms allowing the full signal to be applied to the cap which in turn allows the highs to be passed through the cap to ground with no resistance. So as you rotate CW, the resistance is either increasing faster than you prefer or, its enough to get the highs that you want earlier with a significantly lower resistance than is required to suit your ear. My guess is that all of your problems would go away with 250K tone pots. But just to add some complications to the discussion, I have purchased a guitar cable which did the same thing and the whole problem turned out to be nothing more than a manufacturer getting defect cable from a supplier. Also, different amps and pedals can lead to changes in how the pot tapers are perceived.
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009
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Post by 009 on Jul 13, 2022 15:37:07 GMT -5
Well, I figured out the problem. Treble is only significantly present when the corresponding volume pot is turned up to max (full CW), and the treble control pot becomes almost non-functional as the volume pot is turned CCW just a bit; wicked audio taper. What I need is a treble bleed modification on the volume pot(s) (treble drop-off most notable on neck pickup), if I want to correct some of this. I'll probably buy some caps and resistors to experiment with; I have some alligator clip leads; should be fun. If I just leave the guitar volume pots full up, I get good treble adjustment response from the tone pots. All I have to do is adjust the volume on the amp. This works for the bedroom player, but it's difficult for me to leave well-enough alone. "We're not happy 'til you're not happy" (The Three Stooges Fix-It Shop)
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pdf64
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Post by pdf64 on Jul 13, 2022 17:52:51 GMT -5
Are your tone pots wired 50s style, from the vol pot wipers?
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009
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Post by 009 on Jul 13, 2022 20:51:47 GMT -5
Are your tone pots wired 50s style, from the vol pot wipers? I don't believe so. www.rickenbacker.com/pdfs/19505.pdfThe harness I have is a straight-forward copy of the above schematic. I took a modified harness out that did not seem to work. That harness had two push-pull pots: one to add the second (disconnected, ala Lennon) middle pickup if/when the urge arose, and another identical pots to run the signal through a 0.0047 uF cap (either/or, optionally). I'm going to try to build another harness like that. I think the pots are DPDT, but I'm not sure. The only identification on the pots is the number 603. I'll fool around with the treble bleed, but really, I'd like to make a new harness that works with those two push-pull pots. Lots to learn there, and it would be a real trick to solder treble bleeds on those DPDTs. |
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pdf64
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Post by pdf64 on Jul 14, 2022 3:14:50 GMT -5
Ah, Rickenbacker, they’re a different kettle of fish, a law unto themselves; the volume controls are wired backwards, they operate by loading down their pickup.
Sorry, I should have checked that much earlier, I just assumed it was the standard Gibson style.
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009
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Post by 009 on Jul 14, 2022 7:16:36 GMT -5
No, I should have been more specific. I didn’t appreciate or understand that Ricks are that different. Well, with other things going on (in my daily life/activities), I’ll be taking my time delving deeper into this. Admittedly, turning the guitar’s volume pots fully up and then leaving them there works pretty well for me; I am pleasantly surprised. Thanks.
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