Grounding

[FretlessOnly]

So I'm a bit confused about all this. I know room features such as wiring and light fixtures all contribute to grounding hum (I don't mean single coil PU hum, I mean the baseline "I'm not touching a metal part of my instrument hum). But, all things being equal, I have some basses that, in the same room, are nearly dead silent when I am not touching the metal parts and others, including my two RICs, have quite a bit of that metallic whiny hum (all my grounds have been checked and all are OK, etc).

Is it true that the player completes the ground loop on all electrics? Or, are some better grounded alone without the player making contact with the metal parts of the instrument.

I realize that this may a somewhat stupid question, but remember, there are no stupid questions, only stupid people (in this case, me!).

Thanks,

JM

[ajish4]

John,

I'm going to move this topic to one that will bring you some fine tuned responses. There has been a lot of discussion on this topic in the past, but lets see where we can find some help. Possibly the VIBROLA section.

[johnallg]

John, if you have the grounding in your room checked and under control, but some basses have louder hum than others under the same conditions, I would attribute that to the quality of the grounding in the instrument and the type of pickups and their construction. Also a two pickup instrument with the single coils wound opposite directions would help cancel noise and hum (think Jazz Bass).

[FretlessOnly]

That's the thing; my two Ricks make the most noise and their grounds are set nicely and are only at most 2.5 years old. And it's not pickup hum I'm talking about; it's that real metallic hum that immediately goes away when I touch strings, bridge, etc. My other basses have much less of it; my Fender Mustang guitar has it, but my 650 Dakota has none.

Is it the pickups doing this, or something else? Again, the room is fine; no fluorescents, proper wall outlets, etc.

[johnallg]

Rick uses single coil pickups on the 4001/4003 basses so you will get hum directly into the coils. But if touching the strings/bridge/tailpiece/tuners quiets the hum, I would look at the ground wire from a pot in the cavity that goes to the tailpiece. There should be a black ground wire to the bottom of the mute metal support bar, soldered there. If it is intact, then try playing with the mute screws to see if a better contact can be made.

[FretlessOnly]

All intact. I would add that Jim and John Mouradian, two of the best lutheirs and reapir guys in Boston, told me that the player completes the ground, and that having the noise (I wouldn't call it hum really, it's that really grating metallic sound) is normal, and touching a metal part will remove that noise. And that's natural. Thing is, it isn't natural on all my single coil basses.

[johnallg]

That is not my experience, and not with my Ricks.

[FretlessOnly]

Well, the problem with my 4003FL may be the new pickguardian surround, which secures the ground between the G string side spring and the plastic surround. Is the spring enough to ground, or do I need more metal to connect to?

[johnallg]

Well, the problem with my 4003FL may be the new pickguardian surround, which secures the ground between the G string side spring and the plastic surround. Is the spring enough to ground, or do I need more metal to connect to?

I would put copper tape on the back of the Pickguardian surround plastic and pinch the ground eyelet between the copper and spring.

[FretlessOnly]

Thanks John; I'll give that a try.

[FretlessOnly]

OK, this is driving me absolutely crazy. Mouradian said copper tape will do next to nothing.

Both Rick basses exhibit obnoxious metallic grounding problem. Same with Ken Smith w/ humbuckers. Almost as bad with Fender Jazz. There is nothing wrong with these instruments as far as I can tell. Warwick (passive single coils) is dead silent. Today I unplugged everything from my power strip and just plugged the amp into the wall directly. DIdn't seem so bad. Last week at a home "studio" room (nothing special, just padded) I used a different power strip and the Rick FL was dead silent. Everything else was just as I have it at home.

So, solution: get a new power strip, right?

Nope. I'm out the cost of one Monster power strip and same "annoying to the point of giving up music" problem, even plugging directly into the wall.

I give up.

[cjj]

Have you checked your wall outlet for proper grounding? I suddenly developed a similar problem to yours when I switched from an old Peavey amp to my current rack setup. The rack has a "power conditioner", which is, I think, a power strip with surge suppressor that's rack mounted. I ran this to a power strip and the power amp's plug there as well.

Anyway, I knew the grounding was bad, well, nonexistent actually. This part of the house was built in the 1930's and what is has for outlets don't even have ground pins, just 2 slots. Anyway, I played with different cords, cables, adding straps to the different rack components, etc. I had been fooled into thinking it was a cable issue because the Peavey was so quiet.

It turned out to be the fact that there was no ground. I'm not exactly sure why the Peavey amp was OK, probably because it is all on one board with one power supply. The separate items in my rack have separate supplies so the potential for ground loops exists. Anyway, since I can't ground it, I got a big isolation transformer to break any direct paths on the power lines. Nice and quiet now!

So, it's worth getting one of those little circuit check plug things just to make sure the outlet ground didn't go bad on you. It does happen and could be the cause. The thing with different basses doing it to different degrees (or not at all) is hard to explain though, I only have Ricks and mine were all the same noise-wise...

[FretlessOnly]

It turned out to be the track lighting. Not fluorescent; just those small flood-type bulbs. A couple of lamps solved that. I'll have to check to see if a standard lightbulb in the track lights will still cause the problem. Otherwise, they'll just get shut off when I'm plugged in.

[cjj]

Do you have a dimmer on the lighting? Dimmers "dim" by chopping the sine wave before it gets to full voltage and hence, are extremely noisy...

[FretlessOnly]

Ah, indeed we do (we just bought the house in May, so still adapting to what's here). I've noticed that the buzz is worse with the dimmer set in the middle; it's reduced when the lights are full on or almost off (but still audible).

So, I could remove the dimmer switch, or I could just not use them while playing. Feels much better to know. Thanks for the info!