piezo acoustic electric with hum problem

O

oretez

Hwy 50
Have a friend with an Epiphone Chet Atkins SST. Acoustic Electric solid top piezo etc.

difficulty is buzz hum . . . volume of hum is proportionate to position of guitar's volume pot, frequency of hum is effected by tone pot.

all you have to do is touch jack plate and hum goes away

hum is less pronounced when jack is dangling loose from body (jack plate unscrewed) and what is no surprise is that by physically touching the ground wire (with a bare finger) the hum disappears

I can be wearing rubber soled shoes, be barefoot, be seated in a chair with insulated legs and have my feet off the ground, run through solid state amps, tube amps, change cables, etc. hum's there, touch jack plate hum goes away

in the course of trouble shooting ran through usual suspects, including replacing battery, replaced jack (primarily to check connections simply by resoldering them), and resoldered some connections at the pot preamp end of things (but did not pull piezo nor remove wiring harness entirely . . . while I can take things apart I have less skill with reassembly)

I tried using various configurations of jumpers from plate/barrel of cord to various parts of guitar, none of which eradicated hum . . . .though, again perhaps obviously, a jumper from jack plate to flesh did.

as my friend is not performing pseudo pierced punk the jumper to flesh solution isn't entirely satisfactory

so any suggestions that would keep me from having to rewire the whole damn thing would be appreciated.

thanks
 
Honestly, in all likelyhood the only way your going to fix that one is to just replace everything, which is a problem because Gibson/Epiphone is no longer making (or, more to the point, having L.R. Baggs make) the electronics for those things. We did one of those things for someone recently where we just hardwired the pickup to the jack and sold the guy a Para D.I., which worked out for him, but you loose all of your on-board controls. Or, you could just get a Piezo pre-amp from one of the companies, and do all new electronics, but that would certainly end up costing more (something like a Bartolini AGPB with one of their tone circuits added on would sound good, though you'll wait a year to get the AGPB, so you might want to go with a different system if your in a hurry).


Light

"Cowards can never be moral."
M.K. Gandhi
 
what's frustrating for my friend is that he's had it for 10 years and it's one of those

'didn't used t' do it problems'

I was kind of afraid I was going to end up gutting it (though on the plus side there was a piezo/pre-amp system I have not yet tried that I was looking to experiment with before I cut into an ovation 12 string -- off the top of my head I don't even remember if it was the Bartolini (I found the lead time from vendor to be a bit excessive so it might well be))

thanks for replies

(oh, and while I'm sure it's Korean mnfc, neck is not bad and overall sound is not terrible (and as a rule I hate the run of the mill acoustic electrics, but there are times when deploying a 30 year old wood box and $300 mic just don't make any sense) for combination of price and what he needs it for . . . I can definitely see where I would use it for acoustic slide (emulation) . . . you would never mistake it for a resonator but in the 'mix' @ a typically road house it fills the bill for that voice. . . . it is not a terrible instrument . . . well, except for the hum)
 
Faulty house wiring caused Epi SST hum

oretez said:
Have a friend with an Epiphone Chet Atkins SST. Acoustic Electric solid top piezo etc.

difficulty is buzz hum . . . volume of hum is proportionate to position of guitar's volume pot, frequency of hum is effected by tone pot.

all you have to do is touch jack plate and hum goes away

hum is less pronounced when jack is dangling loose from body (jack plate unscrewed) and what is no surprise is that by physically touching the ground wire (with a bare finger) the hum disappears

I can be wearing rubber soled shoes, be barefoot, be seated in a chair with insulated legs and have my feet off the ground, run through solid state amps, tube amps, change cables, etc. hum's there, touch jack plate hum goes away

in the course of trouble shooting ran through usual suspects, including replacing battery, replaced jack (primarily to check connections simply by resoldering them), and resoldered some connections at the pot preamp end of things (but did not pull piezo nor remove wiring harness entirely . . . while I can take things apart I have less skill with reassembly)

I tried using various configurations of jumpers from plate/barrel of cord to various parts of guitar, none of which eradicated hum . . . .though, again perhaps obviously, a jumper from jack plate to flesh did.

as my friend is not performing pseudo pierced punk the jumper to flesh solution isn't entirely satisfactory

so any suggestions that would keep me from having to rewire the whole damn thing would be appreciated.

thanks
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I recently got an Epi SST 2.0 Classical, and experienced the 60 Hz hum described here. The hum would go away when I touched the metal plate around the jack. My other guitars (steel string, magnetic pickups) didn't have hum. On a hunch, I plugged in the amp upstairs where I know the AC wiring is up to code, and the hum (with the Epi SST) was gone!

The wiring upstairs has a good ground. The previous homeowners wired up the remodeled basement with a poor ground, and piezo pickups are more sensitive. My suggestion is that you make sure you're plugged into an outlet with a good ground. It's safer, and will ensure you won't have a floating ground in your amp that will cause AC hum. For about $10 you can get an outlet checker at the hardware store to let you know if your outlets are wired correctly. If you MUST use an ungrounded outlet (not recommended), you can use an isolation transformer to isolate your amp. Hum eliminator transformers can be found on ebay.
 
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