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| what's wrong with my pots? http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10123&t=36142 |
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| Author: | Ricardo [ Fri Apr 13, 2012 8:49 pm ] |
| Post subject: | what's wrong with my pots? |
My ES-175 clone has been a very enjoyable instrument to play with one exception. I normally play with volume turned up on the guitar and turned down on the amp. This provides the clearest sound. However, if I turn down the volume pot on the guitar and turn up the amp, I get all kinds of hum. Does this suggest I wiring problem or bad pots? I have the same experience on both pickups. Rich |
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| Author: | theguitarwhisperer [ Fri Apr 13, 2012 11:13 pm ] |
| Post subject: | Re: what's wrong with my pots? |
Let's see how it's wired. Do you have a pic? That symptom suggests an open hot somewhere when the volime is turned down on the one pickup, possibly caused by a bad component. |
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| Author: | B. Howard [ Sat Apr 14, 2012 5:26 am ] |
| Post subject: | Re: what's wrong with my pots? |
What shape is your cable in? Any RF interference in the area like fluorescent lights? |
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| Author: | Colin S [ Sat Apr 14, 2012 10:23 am ] |
| Post subject: | Re: what's wrong with my pots? |
Also, don't assume that the fault is in the guitar, does the amp react the same with other guitars? Amps have pots too and can exhibit the same problems. As a high input low amplification works well and a low input high amplification produces hum, maybe you have come up against the natural signal to noise ratio of the amp. If the amp is clean at all volume settings with a different guitar, then you know that it is the guitar at fault. Alternatively of course try the guitar with a different amp to see if the same fault occurs. At least then you'll know where to start looking. This pattern of hum can occur if the two pickups are wired to provide individual volume control when both pickups are switched on. Is the hot wire from the pickup wired to the first lug of the volume and the hot to the switch coming off of the center lug? The volume will work with the hot leads reversed, that is with the switch to the clockwise lug and the pickup to the centre (to allow independent volume control in the centre switch position), but it won't ground out the cable when turned down, so as you turn down the pot the signal to noise ratio gets worse. This independent volume control wiring can sacrifice tone and pot taper for the dubious benefit of being able to turn one pickup all the way off with the switch in the middle. Wire it with the pickups to the outer lugs and the switch leads to the centre lugs, and you'll get better volume control and probably cure the hum problem, too. DAMHIKT! Look at the wiring diagram on Stew Mac site for the Les Paul and you'll see what I mean. They show both wiring patterns, my advice would be to check that you have it wired in the traditional way given in the main diagram. Colin |
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| Author: | Ricardo [ Sat Apr 14, 2012 10:45 am ] |
| Post subject: | Re: what's wrong with my pots? |
Colin, I tried a different cable - same result. I tried a different amp - same result. I did do the alternate wiring which you are suggesting is the cause of my hum problem. Now wouldn't you think that Stewmac would warn about the possible hum problem with this approach? Thanks for your suggestions. I might as well rewire since I have to replace the bum (stewmac) 3 way switch with a Switchcraft. I wonder if I should repace the Stewmac pots with genuine Gibson ones? (requires larger holes and different -fine thread knobs). Dang! Rich |
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| Author: | alan stassforth [ Sat Apr 14, 2012 6:40 pm ] |
| Post subject: | Re: what's wrong with my pots? |
I don't think it's the pots or the switch. Does the hum go away when you touch the strings? What kind of amp? |
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| Author: | Ricardo [ Sat Apr 14, 2012 6:51 pm ] |
| Post subject: | Re: what's wrong with my pots? |
Yup it goes away when I touch the strings. But I only have the hum when I roll off the volume pot - at full volume, no hum. |
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| Author: | alan stassforth [ Sat Apr 14, 2012 7:51 pm ] |
| Post subject: | Re: what's wrong with my pots? |
Sounds like a grounding problem. Check the bridge to see if it's grounded. Or, just make sure your fingers are always touching the strings. |
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| Author: | Ricardo [ Sat Apr 14, 2012 7:52 pm ] |
| Post subject: | Re: what's wrong with my pots? |
Thanks, with my archtop - wood bridge, wood tailpiece, its a bit of a challenge getting a great ground. I'll keep the vol pot up and control volume at the amp. Seems this way I have no problem. thanks |
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