Noisy Wiring/Amps?

[Danley]

So to start, I have something weird going on in the wiring of my house. I've pretty much narrowed this down, because I have a battery powered/AC amp that has tons of buzz when I use wall power (have even tried reversing the plug polarity, with no good result.) Yet when using battery power all my guitars play through it with no noise. I also don't hear any noise other than 60 cycle hum where applicable when playing through an audio interface.

I only have this issue when plugged into the wall, BUT: for whatever reason my Jackson Soloist is still totally noise free using AC power; and my Jazzmaster (even with RWRP/both pickups selected) makes much more noise than the rest. My other guitars (both humbucker and single-equipped) make a more marginal amount of noise, but are still noisy. So takeaways:

• Would a power conditioner solve for the noise somewhat (given the two amps in question are a 5 watt Vox AC4 and a Silverface Champ?) Should I be looking toward another solution first?
• Why would certain guitars be affected by the wall issue more than others? I get that Jazzmaster pickups are huge noise antennas, but shouldn't it not matter if I have RWRP and both pickups engaged?
• I'm sure this isn't a ground issue with the guitars - I just totally ripped apart my Jazzmaster's wiring and checked all possible places, bridge etc. for ground continuity with a multimeter. I even created (then repaired) a ground issue just to experiment and understand how a ground buzz would come through, and it's not that

[timtam]

These things are difficult ... semi-random thoughts ...

Yet when using battery power all my guitars play through it with no noise.

That does suggest that the noise source is not airborne EMI from non-amp sources getting into the guitar, as that would be similar when on batteries. When on AC power and noisy, is there much of a noise difference when touching guitar metal (ie grounding yourself) or not ?

Can you battery-power either amp or just one ? Was the other amp AC-connected and ON at the same time as battery-powered rig was quiet ?

I only have this issue when plugged into the wall, BUT: for whatever reason my Jackson Soloist is still totally noise free using AC power; and my Jazzmaster (even with RWRP/both pickups selected) makes much more noise than the rest.

Soloist is HB or SC model ? In any case, this suggests either that it's not a systemic power problem (somewhat contrary to battery findings, ), or that that guitar is very immune (HB ? shielding ?).

JM is direct into amp with no effects and amp is direct into wall (no power boards or extension cords) ?
Same noise with both amps ?
Has JM been modded ? ie have you verified RWRP ? Is it shielded ? Is shielding grounded ?

I assume different cables tried ?

[Danley]

That does suggest that the noise source is not airborne EMI from non-amp sources getting into the guitar, as that would be similar when on batteries. When on AC power and noisy, is there much of a noise difference when touching guitar metal (ie grounding yourself) or not ?

A bit of difference (less noisy) when I touch strings/metal using AC - but no difference using battery (still quiet.)

Can you battery-power either amp or just one ? Was the other amp AC-connected and ON at the same time as battery-powered rig was quiet ?

I wasn't totally clear in the post - but both the Vox and Champ are only AC, the battery powered amp (that I can also plug in AC using an adapter) is a small portable test amp I have on my workbench. I didn't test both the battery and AC at the same time, though I went back and forth many times in a short span.

Soloist is HB or SC model ? In any case, this suggests either that it's not a systemic power problem (somewhat contrary to battery findings, ), or that that guitar is very immune (HB ? shielding ?).

Soloist is humbuckers. I have one other HH guitar where the noise still does come through somewhat on AC, but this Soloist is absolutely silent. The single coil guitars that are RWRP still have a bit of noise as well - not as much as the Jazzmaster though (worth it to mention - my two other Jazzmasters are also in that middle-area of being prob. too noisy using AC, but less so than the particular Jazzmaster I'm talking about.)

JM is direct into amp with no effects and amp is direct into wall (no power boards or extension cords) ?
Same noise with both amps ?
Has JM been modded ? ie have you verified RWRP ? Is it shielded ? Is shielding grounded ?

Yep - no pedals (even tried using one as a buffer, no dice) straight into amp, amp direct into the wall. Same noise with both amps. JM has def. been modded; it's an American Special which did not originally have shielding (so I added copper tape.) Grounding works and is connected to the copper, has continuity through my multimeter - I seriously checked everywhere I could think of, re-did solders etc. It's definitely RWRP, using the battery power (or interface) I get 60 cycle with individual pickups- but silent on 'both.' Come to think of it I take it to my guitar teacher's studio and play through his amp no problem.

It's strange - for a fairly long while my amps were packed up while work was being done on the house (no electrical though,) and I only used my interface to play. Now I pulled the amps out and I'm hearing this.