Pbass noise issues (SD Quarter Pounder)

[Jerry_B]

Hi all

I've recently put some SD Quarter Pounders into a Frankenfender Pbass. These are going through a wiring harness made by KiOgon, with Alpha mini pots. The strings are D'Addario nylon tapewounds. Despite adding some copper tape shielding, especially to the underside of the scratchplate, I'm having a few issues that I'm a bit mystified by.

First of all, there appears to be some sort of grounding issue, even though I've taken the bass part twice and made sure everything is correct (i.e. wires are going into the right pots, ground wire is sitting nicely under the bridge). There is a certain amount of noise, which typically goes away when I touch the bridge, controls, etc. If I touch the poles on the forward, neck-side block of the pup, it buzzes a lot. This doesn't happen with the rear, bridge-side block. That one stays silent. I know the pickups are pretty hot but these noise issues seem a bit odd.

Secondly, when tightening up the nuts on the underside of the control knobs so that the pots are secure to the underside of the scratchplate, if I do this normally the bass tone goes completely muddy. If I loosen the tone pot slightly, the muddiness goes away.

I'd be very grateful if anyone could enlighten me as to why these things are happening! I've been using the bass a lot recently for recording and the noise issues are pretty annoying

[Kevsy71]

I've just had a similar grounding issue on my P - even though the earth wire from the pot was splayed and sitting under the usual BBOT. Possibly it was the pressure of the bridge making the strands sink into the paint, and reduce electrical contact with the bridge. So I scraped back the underside of the bridge plating to expose some copper, so that I could get some solder to stick. Then I braided the earth wire, and coated it with solder, and finally soldered the earth wire to the solder on the bridge. Which fixed it

[KiOgon]

Hi Jerry,

Can you send me some pics of the wiring, pots & shielding? My kits have continuous earth wired throughout so it sounds like maybe a trapped wire or a tone pot tag touching earth somewhere.

If you swap pick ups you can eliminate that, a buzz from touching the pole pieces can indicate a break down of the insulation inside the pick up.

Cheerz, John

Edited May 17, 2017 by KiOgon

[Jerry_B]

Unfortunately the bass is elsewhere at the moment and I won't be playing it again for a few weeks. This means I can't take any photos. WRT the bridge wire under the BBOT, I made sure that there was a small piece of copper tape on the body that the exposed wire was resting on before the bridge went back on. I was hoping this would fix the problem but it seems to have made no difference. The pups are brand new so I'm hoping that they also not faulty.

[project_c]

you're getting hum because of the tapewound strings. this is a known thing and it happens under certain conditions, dimmer switches are a big contributor but other things can cause it too, computer monitors etc.

Same with almost any other coated string, its something you need to take into consideration when using coated strings.

[Jerry_B]

[quote name='project_c' timestamp='1495027772' post='3300608']
you're getting hum because of the tapewound strings. this is a known thing and it happens under certain conditions, dimmer switches are a big contributor but other things can cause it too, computer monitors etc.

Same with almost any other coated string, its something you need to take into consideration when using coated strings.
[/quote]

Hmm - I'm not so sure. I have tapewounds on another pbass and there are no issues with them at all WRT noise. In fact, this bass I'm asking about has had tapewounds on it but with some older electrics inside and there was no hum then either.

[Grangur]

As Kiogon says, if your tone pot is losing function when you tighten it down there's something wrong there. It's also probable that there is only 1 fault.

Edited May 21, 2017 by Grangur

[project_c]

[quote name='Jerry_B' timestamp='1495037039' post='3300760']


Hmm - I'm not so sure. I have tapewounds on another pbass and there are no issues with them at all WRT noise. In fact, this bass I'm asking about has had tapewounds on it but with some older electrics inside and there was no hum then either.
[/quote]

Put some rounds on the bass and see if it makes any difference

[Jerry_B]

[quote name='project_c' timestamp='1495325225' post='3303028']
Put some rounds on the bass and see if it makes any difference
[/quote]

I would if I had any, but it's odd that this problem only happens with one particular bass. Like I said, my other pbass with tapewounds has no issues.

[project_c]

Checking with rounds (or any unwrapped strings) will at least eliminate that as an issue. I have 3 Precisions strung with tapes, and some of them suffer from it more than others so I'm familiar with this problem, although I have to say for me the problems are caused by a dimmer switch downstairs, and when it's turned off, the hum is gone. The fact that only one side of your pickups is doing this suggests that it could be an issue with the pickup though, so it may be worth trying different pickups in there. But personally, I would just buy a cheap set of rounds for under a tenner and do a quick test before splashing out on new pickups.