stabarah Posted February 21, 2009 Share Posted February 21, 2009 i have a discussion going "hope it doesnt explode" about me customizing my les paul. But im wondering how pots work. if every pot can do anything depending on wiring or if there are specific pots for tone, volume etc. I really need to know everything about pots and how to wire as well as any other things that might help. as for the four pots on my les paul: the neck and bridge volume stay there, one other pot become's mid tone ( i need help on that because all that's left there is tone knobs, and im wondering if i need a whole new pot). And the old neck tone becomes master tone. i know its anoying posting to topics for the same guiatr customize. but this one just has to teach all i need about pots. -thanks Link to comment Share on other sites More sharing options...
InsideMan Posted February 21, 2009 Share Posted February 21, 2009 Well, let me start the ball rolling. I'm sure others will be able to build on this based on their experience. Modern potentiometers are made from a disk with a resistive material applied to its surface and a metal wiper that allows a length of the total resistor to be tapped off and applied to the circuit (of course, the resistive material does not complete the circle). By selecting the type of material and its layout on the disk, the characteristics of the pot can be modified. (There are also wire-wound pots available, but these can be noisy and non-continuous.) The two most important characteristics of the pot are its total resistance (250K, 500K, etc.) and its taper (linear or logarithmic). The resistance is chosen to match the circuit impedance of the guitar. The taper is chosen for the control's purpose--volume controls often use a logarithmic (or audio taper) pot because the human ear perceives sound level logarithmically. Audio taper pots can also be used for the tone control. Pots have three connection points, the resistor top, the resistor bottom, and the wiper. Volume controls often wire the top to one side of the pickup, the bottom to the other, and use the wiper as the output. Tone controls often don't wire the top connection. Rather, they put the pot in series with a capacitor across the pickup output. When the pot is at full resistance, this combination filter circuit presents a high impedance path for high audio frequencies, so the output of the pickup is "bright". When the pot is at its lowest resistance, the capacitor is a shunt for the high frequencies, so they don't appear in the output and the pickup is more "muddy". I think it's great that you want to understand what' going on with pots, and not just wire them in. Good luck with your projects. Cheers. Link to comment Share on other sites More sharing options...
stabarah Posted February 21, 2009 Author Share Posted February 21, 2009 nice going, insideman. this a great help for me. Do you think i could turn an old bridge tone into mid volume and neck tone to master tone? Link to comment Share on other sites More sharing options...
TWANG Posted February 21, 2009 Share Posted February 21, 2009 look at your pots.. some are audio taper.. marked A some are linear taper.. marked B audio for volume or tone. but linear for tone only. a .001mF cap across the left or number one lug to the middle.. *lugs pointing down, left is no. 1, looking at the back of the pot* will bleed treble, hence the name treble bleed, when you cut volume. that means that without it, as you turn down the volume, you lose some highs.. put in the treble bleed cap and it allows the highs to pass and the tone of your guitar is therefore unaffected by the change in volume. cheap, too! cents at radio shack for ceramic chip capacitors for treble bleed. You may very well have linear taper pots.. so you can't use them as volume pots. Capacitors are also cheap, and you may find sprague orange drops a nice inexpensive upgrade while you're in there. Except for the type of pot, you can do what you wanted to do. TWANG Link to comment Share on other sites More sharing options...
InsideMan Posted February 21, 2009 Share Posted February 21, 2009 Stabarah, it all depends on the values of the existing pots and the values you need for your circuit. As an example of what I discussed before, here is a 3-pickup LP schematic: As you can see, this schematic uses 500K audio taper pots for both volume and tone. Of course, this particular schematic doesn't have a master tone or mid-volume control. Do you have a schematic or diagram for the circuit you want to wire? (It's easier if you do). Otherwise, you will have to experiment. There are a wide variety of schematics on the Gibson site. http://www.gibson.com/en-us/Support/TechSupport/Wiring%20Diagrams/ Link to comment Share on other sites More sharing options...
stabarah Posted February 21, 2009 Author Share Posted February 21, 2009 well, this is odd BECAUSE THE TWO VOLUME pots say B500k ohms and the two tone pots say A500k ohms. maybe you made a typo because you said that the ones marked B (my volume pots) are linear and are only for tone. maybe im reading the wrong spot but its the only place with writing on the pots. Dunno Link to comment Share on other sites More sharing options...
InsideMan Posted February 21, 2009 Share Posted February 21, 2009 OK. I took a different tack. I asked myself "Given the original pots, how could this be wired" and came up with this: This calls for 4 audio taper pots. In any event, to avoid "weirdness" (i.e., one volume control doesn't act like the rest), you should have all 3 volume pots the same. It probably wouldn't hurt to buy new pots, they get worn and the ones on a new Epiphone may not be the highest quality. Cheers. Link to comment Share on other sites More sharing options...
stabarah Posted February 21, 2009 Author Share Posted February 21, 2009 sure, so then i replace the old linear for new audio? Good stuff. And what is the avantage of linear tone over audio tone? Link to comment Share on other sites More sharing options...
stabarah Posted February 21, 2009 Author Share Posted February 21, 2009 there's no way im experimenting, i will make a schematic and double check with my luthier first. thanks man Link to comment Share on other sites More sharing options...
InsideMan Posted February 21, 2009 Share Posted February 21, 2009 And finally, here is a variation with 4-lead ("center-tapped") humbuckers, in case that is your style. You would have to go with a ganged pot/switch. (The dotted line is to show that the switch and pot are ganged.) With this setup, you would pull (or push) the volume knob to change its pickup from double-coil to single-coil. (Cool, huh!) This might be the most versatile tone setup around. As for linear versus audio taper, with an audio taper you would turn the volume down from 10 to 5 and it would SOUND like you turned the volume down by half (because your ears respond to the logarithm of the sound level, not the actual level). With a linear pot, it would not sound like half volume. In the tone circuit, the effect is not as easily described, but it too benefits from an audio taper. Cheers. Link to comment Share on other sites More sharing options...
stabarah Posted February 21, 2009 Author Share Posted February 21, 2009 thanks for the help on schematics, insideman. But if you read the other topic "hope it doesnt explode", you will see that all the schematics are worked out, im just waiting for a diagram by generation zero. This topic was really just for pot choices and what i need to know about them. Link to comment Share on other sites More sharing options...
TWANG Posted February 21, 2009 Share Posted February 21, 2009 linear pots have a different curve. in the vol. position they tend to go from nothing to loud with a small turn. in the tone position it's different.. they curve up smoothly. tWANG Link to comment Share on other sites More sharing options...
face Posted February 22, 2009 Share Posted February 22, 2009 stabarah, twain has mentioned this before and i saw it elsewhere, some "modern" epis come from the factory with b500's for volume and a500's for the tone. i just opened mine up and swapped them and put some paper in oil caps on the tone and changed it vintage lp wiring schematic and this dramatically changed the tone of my guitar. hope that helps. Link to comment Share on other sites More sharing options...
stabarah Posted February 22, 2009 Author Share Posted February 22, 2009 if you check the topic "hope it deosnt explode", you see that my wiring problems are all ruled out as well as pots. Im want 500Kohm pots on tone volume volume volume. Is that right ohmage? Link to comment Share on other sites More sharing options...
TWANG Posted February 22, 2009 Share Posted February 22, 2009 yes! 500K. TWANG Link to comment Share on other sites More sharing options...
stabarah Posted February 22, 2009 Author Share Posted February 22, 2009 ill order it all off guitar fetish if i can Link to comment Share on other sites More sharing options...
stabarah Posted February 22, 2009 Author Share Posted February 22, 2009 check "hope it doesnt explode" for my list of gear im getting, please comment Link to comment Share on other sites More sharing options...
stabarah Posted February 22, 2009 Author Share Posted February 22, 2009 capacitors? im also gonna need to know everything about those and which ones i should buy for my new setup. Link to comment Share on other sites More sharing options...
Dave Posted February 23, 2009 Share Posted February 23, 2009 The technical explanation of audio vs linear taper comes from the fact that your ears don't respond to volume changes in a linear fashion. It takes a 3db change to make your ears hear a difference. a 3db change in volume or loudness is actually a doubling of sound pressure or level. This is why a 100 watt amp doesn't sound twice as loud as a 50 watt amp. It just sounds "louder". The audio taper pot changes resistance in a fashion that makes your ears respond in a way that you think that halfway down is half volume. It is really a 3db change if you hear the volume change as half loudness. If the volume control were linear, you would not percieve the volume change to be linear. An audio taper pot uses a logarithmic change that equates to the db scale of loudness. Each equivalent change in position changes with the log of the resistance rather than each position being an equal change. For instance, a linear taper 500k pot would change 50k for each position from 1 to 10. An audio taper pot would change by half for each change in position. 1 might be 500k, 2 would be 250k, 3 would be 125k, and so on until you are at 0 ohms for full volume output. Link to comment Share on other sites More sharing options...
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