Troubleshoot buzz/hum with my MTD Kingston Super 4

[lastminute]

I ordered a used MTD Kingston Super 4 from GC online: figured I could return if it wasn’t a keeper. Now, the bass itself sounds great. But I am having some noise related issues with it:

1) There’s a buzz when I’m not touching the strings. My other active basses, including my Stingray and my ATK805, are pretty quiet when I do the same with them, so I was surprised. Even funnier, the noise only gets slightly quieter all when I touch the D and G strings, like 30%; and then it goes 95% away when I touch the A string, and completely dissipates only when I touch the E string.

2) if I’m not touching the strings, the buzz also goes away if I touch one of the knobs, tuners, or switches for the single/series/parallel. Funny enough, touching the bridge also does it, but not quite fully: it’s like 95% but a tiny hint of noise coming through.

3) When I’m NOT touching any of the above, there’s also a terrible a buzz when I touch the pickup covers. Not the poles, mind you, but the covers themselves, like if I’m anchoring my thumb on them. And more importantly, if I’m touching the ADG strings, but not the E string, the buzz when touching the pickups still happens, but when I touch the E, all gone.

Funny enough, the overall buzzing noise goes away when I touch the metal pickup pole pieces, just like the items in points 1&2.

EDIT: new point #4. If I touch the E string over the frets, it cancels out the buzz, but if I touch the part of the string that goes beyond the neck and over the body and pickups, it stops canceling it, or at least only a small amount that’s hard to decipher. Weird.

Possible culprits?

 

[iplay5strings]

Whenever you touch metal on the bass you are completing the ground circuit. Fully shield the electronics cavity with copper, ground the bridge wire to the copper, and you will no longer need to be what completes the circuit.

 

[lastminute]

Whenever you touch metal on the bass you are completing the ground circuit. Fully shield the electronics cavity with copper, ground the bridge wire to the copper, and you will no longer need to be what completes the circuit.

The funny thing is, this bass (and all medium tier and up MTD basses) is supposed to come with a fully shielded electronics cavity: it’s part of what they promote in their specs. So I don’t think that’s the issue? Unless perhaps since this is a used bass, something with the ground wire failed?

I also feel like with all the random little conditions under which the noise cancels out or doesn’t, it might not be as straightforward.

 

[Bass Viking]

I have the same model bass and don't have that issue. My guess is it's a loose wire. I haven't shielded mine.

 

[Jackass76]

Agreed about the shielding…sounds like something is loose…open it up and see if you can find a loose wire.

I also had a battery with an internal quirk make noise once, not saying it’s your issue, but can’t hurt to check.

 

[Matt Liebenau]

Check that the shielding exists and is properly grounded. Shielding with no ground connection is worse then no shielding.

 

[lastminute]

Thanks for replies everyone. I’ll check inside. If I’m finding loose stuff I’ll need to debate whether to just return it or have someone fix.

 

[Bass Viking]

Just a heads up: the control cavity cover is very snug fitting, at least mine is.

 

[lastminute]

Just a heads up: the control cavity cover is very snug fitting, at least mine is.

Yeah, I tried as hard as I could but couldn't get it out. What did you do to get it out?

 

[Bass Viking]

Yeah, I tried as hard as I could but couldn't get it out. What did you do to get it out?

Usually I hold a piece of tape, stick part of it on the cover, and pull it off. That didn’t work. I finally got it off by inserting a small flat head screwdriver in the screw hole of the cover and prying/lifting it off.

My Spector has a control cavity cover that sits on top of the body ie. not flush. Makes things a lot easier!

 

[Matt Liebenau]

Yeah, I tried as hard as I could but couldn't get it out. What did you do to get it out?

I use a small suction cup. You can usually find them at Walmart or the grocery store for hanging things on windows.

 

[Bass Viking]

I use a small suction cup. You can usually find them at Walmart or the grocery store for hanging things on windows.

Good idea. This may not work on the MTD though, it’s VERY snug. Maybe a Shop Vac?

When I finally got my battery compartment cover off I sanded the edges to make it easier to remove next time.

 

[lastminute]

Big update. So my peek inside was inconclusive, so I ended up returning the used bass. I ended up ordering a brand new Super 4 from Bass Central, who in turn ordered one straight from the factory to my doorstep, With their contact even doing a quality check of the bass before sending it out, specifically looking for the problem I named here.

So the good news is with the new bass, It will quiet down the minute anything metal is touched, including any one string (no more inconsistency where some areas do it and some don’t).

The bad news is there still Is buzz when I’m not touching strings/any metal parts, despite this bass’s electronics cavity supposedly being shielded from the factory. The noise gets worse when I touch the pickup that’s selected (but not if it’s not selected).

However, on the other hand, I revisited and tested my other basses, and got a shock: my Musicman SUB USA bass has the same behavior, as does my Sandberg Basstheworld signature jazz bass.

My Ibanez ATK805E has present but quieter buzz when not touching any strings/metal parts, and DOESNT have a noise increase when touching the pickups.

Am I to conclude that perhaps the problem isn’t that my consecutive Super 4s were duds, but just that maybe the shielding isn’t as strong/thorough as hyped from the factory? And perhaps I’m in a really noisy environment playing at home? Perhaps there are other factors I overlooked?

 

[Bass Viking]

Try the bass in a different room, building, electrical outlet, etc. Maybe through a different amp?