OldGuitarGuy Posted February 25, 2019 Share Posted February 25, 2019 I have an Epiphone Les Paul Standard made in Korea in 2004, and an Epiphone G400 Pro made in China in 2012. Both have volume pots that seem to jump from no volume to high volume too quickly but not much adjustment after the initial 30 degrees of rotation. Any ideas why and how to fix? They seem quirky. Should I replace the pots? If so, with what brand, type, ohms? Link to comment Share on other sites More sharing options...
kidblast Posted February 25, 2019 Share Posted February 25, 2019 Not sure what these are but there's two categories pots with regards to this. Linear and Audio Taper. I could have this bass-akwards, but I think Linear pots will do what you're noticing. There could be other things too but if these are stock with no mods, you might want to see what's in there. Link to comment Share on other sites More sharing options...
NighthawkChris Posted February 25, 2019 Share Posted February 25, 2019 Not sure what these are but there's two categories pots with regards to this. Linear and Audio Taper. I could have this bass-akwards, but I think Linear pots will do what you're noticing. There could be other things too but if these are stock with no mods, you might want to see what's in there. Kid, yes, this will have a different characteristic. The audio taper you are referring to are more logarithmic in their resistance "delivery" as they are rotated - and this is what you may want to have in the guitar. I mean, this is not ALWAYS true. The Gibson Nighthawk design incorporates a 300kOhm linear potentiometer for the volume, and a 500kOhm for the tone - go figure... I would bet that LPs (even Epiphones) are intended to have a 500kOhm audio taper though. Anyhow, yes, I agree with you 100% that this seems like a linear taper potentiometer is in place here. OP, I'd look up schematics and figure what circuit is to be assembled. Usually a good schematic will specify the taper of the potentiometers being used in construction. It would be interesting for you to take a look ans let us know if you see any evidence of "custom" modification. Either way, replacing potentiometers is not difficult and takes minimal soldering skills if you're up for the task. There are plenty of online videos on how to do this stuff. But then again, if you're not up for it, that's fine too... You wouldn't want to do a job that you aren't too confident with your tool-wielding abilities. But point is that kid and I based on your description would clearly point to a linear tapered potentiometer in play here. Replace with a 500kOhm audio tapered potentiometer and you will definitely notice a difference - and give you what you'd expect. Best of luck here! Link to comment Share on other sites More sharing options...
kidblast Posted February 25, 2019 Share Posted February 25, 2019 Kid, yes, this will have a different characteristic. The audio taper you are referring to are more logarithmic in their resistance "delivery" as they are rotated - and this is what you may want to have in the guitar. I mean, this is not ALWAYS true. The Gibson Nighthawk design incorporates a 300kOhm linear potentiometer for the volume, and a 500kOhm for the tone - go figure... I would bet that LPs (even Epiphones) are intended to have a 500kOhm audio taper though. Anyhow, yes, I agree with you 100% that this seems like a linear taper potentiometer is in place here. I've always gone with the assumption for Volume controls, Audio Taper is more compatible to what we're looking for. Link to comment Share on other sites More sharing options...
MikeRom Posted February 25, 2019 Share Posted February 25, 2019 My gibby les paul standard is like this too. If i wasn't so lazy I'd change them out to the audio taper pots. I'm more worried tho about making a change that could affect the character of the sound. Link to comment Share on other sites More sharing options...
kidblast Posted February 25, 2019 Share Posted February 25, 2019 My gibby les paul standard is like this too. If i wasn't so lazy I'd change them out to the audio taper pots. I'm more worried tho about making a change that could affect the character of the sound. My 2002 Gibson LP Standard was like this, - I did change the pots to Bourne Audio Taper and it made a pretty big difference to the + side Link to comment Share on other sites More sharing options...
mihcmac Posted February 25, 2019 Share Posted February 25, 2019 Audio Taper I think is the key word, but the G-400 Pro has Coil Tapping and uses 500k Push/Pull pots that are kind of rectangular and taller than the standard 500k pots. If the Les Paul Standard has Coil Taping it would use similar pots as the G-400 Pro, if not they would be standard audio taper 500k's. Pic's would help determine exactly what you have. Note that Epiphone push/pull 500k pots usually have several wires going to multiple vertical connections attached to the side. I found this image on google of an Epi Les Paul with the rectangular push/pull pots that would be the same on the G-400 Pro.. Note that the Korean era push/pull pots may look a little different, but would function the same way.. I usually rewire with standard 1' diameter 500k audio taper pots an lose the coil tapping.. Note note 4 wire pickups with a ground are designed so you can split the coils for coil tapping. The coils can just be wired in series to function like a normal 2 wire pickup. Link to comment Share on other sites More sharing options...
NighthawkChris Posted February 25, 2019 Share Posted February 25, 2019 In the end of the day, resistance is resistance to me. Just saying because I have played with electronics for a long time in my life. I am an electrical engineer (graduated from U of Michigan), worked in the automotive industry for over a decade (again, I live in the motor city - nothing but automotive engineering jobs around here), and I have dealt with many more complicated HW/SW designs that blow away an electrical guitar. I have made my own amplifiers - which in fact was my senior project where my team of students actually worked on amp modelling via VST plug-ins and such. I built the pre-amplifier stage where the others were responsible for the power amp, cabinet design, and SW integration. In the end of the day, when you have a pickup that delivers a signal, it is to be loaded onto the potentiometer. How the wiper is actuated will determine what particular resistance will be set at the wiper. Yes, you may have a tolerance issue where the total resistance of a pot is different from another, but in the end of the day, if you have X resistance loaded to the output jack, you will get that same signal. Now if the pot is constructed like crap, you will get issues where the wiper is having contact issues internally, and that has no direct impact on the simply R factor of the wiper. All things said, if you say buy CTS pots, they are just high-quality construction - what you are actually getting. This is why I never understood why people get their panties in a bunch with the PCBs and all that other junk. In the end of the day, we think we get better tone with hand-wired stuff which actually has more capacitive/inductive losses and such which DO affect the frequency response of the output signal. Whatever with that. All in all, the fact here is that if you are turning the pot 1/8 turn and you get a "0-60" volume increase, then yeah, the pot is drastically being loaded on and causes the signal to have a higher amplitude when sent into the amp's preamp circuit. With a logarithmic (i..e audio) taper, your resistance changes are very slow until the last few "turns" of the pot shaft. Hence why the audio taper is more desirable for an electric guitar circuit. Overall, pots are super-simple things. They are variable resistors, and either you have a quality built one where the wiper is making smooth contact with the resistive material internally or not, but the resistance of a crappy pot that is X Ohms or a good pot that is X Ohms will be just that - X Ohms. The electrons have no bias here when it comes to objective "Ohms" of resistance. Yes, better pots will give better response when actuated, but in the end of the day, the frequency response will behave on the only electrical quality the pot represents - resistance. Not trying to bust balls or anything here, but it just drives me nuts when I have studied this stuff for years, work in the industry on much more complicated things, and I see this subjective stuff take precedence over the actual objective facts how electricity works - especially with passive componentry. And when you get say, CTS pots, they will turn smoothly, have a better tolerance, not get scratchy when rotated - just quality construction and delivering the resistance without a battle. Cheap pots that get scratchy, rotate very rigid, and have a wide tolerance of overall R values will be reflection of poor construction. But still, if you have X resistance loaded on, the sound will be equal to that of the CTS pot with the same X resistance. There's no magic here, it can be easily quantified. Link to comment Share on other sites More sharing options...
MikeRom Posted February 25, 2019 Share Posted February 25, 2019 Get explanation nighthawkchris. I studied electronics engineering and it seemed to me that's the way pots should work but as mine doesn't I concluded that it must be the wrong type (liner vs audio). Didn't occur to me that it may be just a crappy pot. Link to comment Share on other sites More sharing options...
OldGuitarGuy Posted February 26, 2019 Author Share Posted February 26, 2019 Does anyone have any experience with Gibson audio 500 pots? I saw some good reviews. Any difference in experience of quality from CTS? Would they fit the epiphone holes and knobs? Thanks for the tech input. Good stuff. Link to comment Share on other sites More sharing options...
kidblast Posted February 26, 2019 Share Posted February 26, 2019 Does anyone have any experience with Gibson audio 500 pots? I saw some good reviews. Any difference in experience of quality from CTS? Would they fit the epiphone holes and knobs? Thanks for the tech input. Good stuff. The question would be who does Gibson/Epiphone get their components from? Gibson USA guitars could use something like CTS or Bourne, but I've really not a clue. The fit would really depend on the shaft size. These should be documented as part of the specs, you'd need to just measure what you have now. Keep in mind when ordering, you'll want LONG SHAFT since the shaft has to get thru the top which on a LP, with a carved top will be thicker and needs the longer shaft size. I can only say that I've used both Bourne and CTS and I have never had a complaint with either. Easily found online, places like Stew Mac and other supply warehouses. Link to comment Share on other sites More sharing options...
mihcmac Posted March 1, 2019 Share Posted March 1, 2019 I have an Epiphone Les Paul Standard made in Korea in 2004, and an Epiphone G400 Pro made in China in 2012. Both have volume pots that seem to jump from no volume to high volume too quickly but not much adjustment after the initial 30 degrees of rotation. Any ideas why and how to fix? They seem quirky. Should I replace the pots? If so, with what brand, type, ohms? Revisiting the original question, under what conditions does this happen ie the position of the selector switch? When you have one pickup selected, is it normal? Or when both pickups are selected, in mid position, and you have one volume control on and one off then returning it to on? This 0 to 60 condition seems to be most prevalent when the switch is in mid position and you use one volume control to shut off then turn on.. Specially with push pull volume pots.. Link to comment Share on other sites More sharing options...
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