Ground issue?

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I've noticed the past couple months that my bass has a decent amount of buzz to it. I thought it was all the effects I've been adding, but process of elimination brings me to believe its some sort of ground issue within the bass itself. I've eliminated all effects, switched cables, etc. When I tough something metal on the bass it goes away.

Heres a clip:


Any idea what to check for, look for and how to fix it?
 

Florin

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Hi Adam - is it the STreamer LX, so active pickups?
Does the sound goes away when you touch the strings?
 
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Yes, I forgot to say it was the LX. Yes it does go away when I touch the strings. Although if I am not crazy, I do believe the Red Devil strings from DR and making it more noisy when touching the string, as the sound does not completely go away when touching the strings like it did before.
 

Florin

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Yes, that was my guess :) This happens with coated strings... I used to play Elixirs before, but the noise used to go away after a couple of weeks. You can also check the shielding, that helps a lot. The lid should be shielded as well, and it should be a contact point with that little copper thingie on the frame :)
 
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I guess I wasn't the first!

It is quite the annoyance. Although I am sure it wont come through in any form through a live mix, but man its annoying!! Thanks Flo!
 
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Now I feel dumb, but smart at the same time.

I was reading into it a bit more and somewhere I read to check and see if there was a dimmer switch nearby, sure enough I have one in my kitchen. So I run across the house and turn it off, and come back and I am noise free again. I checked it a couple more times to make sure, but seriously what a dumb luck thing.
 

Florin

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LOL, my fault, I considered you a grown adult, and never asked you about fridges, dimmers or coffee machines :)))

Hahahaaaa!!! Well good to know it is solved!
 

DiMarco

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Dim dimmers. We hates them!
 
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And the damn fluorescent lightbulbs! LED bulbs are the way to go but cost and arm and a Warwick.
 
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I'm also experiencing hum with my Jazzman. I thought it was because of the single coil, but as Florin mentioned maybe the DR Neons are the main cause.
 
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I'm also experiencing hum with my Jazzman. I thought it was because of the single coil, but as Florin mentioned maybe the DR Neons are the main cause.

Does the hum stop when you touch the metal on the bridge?
 
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Yes it does. Same case when I touch the knobs or the metal on the cable.

Yeah, I'd change those strings, I've never really liked coated or tapewound strings for this reason, unless it was on an acoustic bass or something.

But I'd also look at the grounding and shielding of your bass. A well shielded/grounded bass should be grounded through the cables and you shouldn't have to touch the strings/bridge to do it (depending if the outlet you're plugged into has a ground anyway).

One thing I've always thought is that the inside of the removable cavity control plate should have some shielding as well, possibly with some copper foil tape, with a grounded section in the clips to ensure connectivity (or just put a grounding screw and wire to the main cavity to ensure connectivity).
 

Sean Fairchild

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Hi guys,

This is not an issue of what strings you use (primarily), and whether they're coated or not. As MatthewJH suggests above, this is a shielding issue, with a possible grounding issue compounding it.

I just got a new-to-me Streamer LX 6-string (hurray!!) and it had the stock MEC split magnet soapbars and MEC 2-band EQ. It had shielding issues, for sure. It was all stock, and made in 2002. It would present buzzing when not touching a metal element of the bass. That isn't normal, and you don't have to put up with it!

I was going to swap out the stock preamp for an Aguilar OBP-3 anyway, so this weekend I took all the guts out of the bass and went to work. Before I did anything, I tested the black "conductive" paint shield in the control cavity with a multimeter, and there was actually no continuity - no conductivity. This means it was not functioning like a shield at all. You can test this with a multimeter by putting the two probes at any 2 spots covered by the paint and setting it to the mode for impedance/Ohms, and it should read 0 or very near 0. If it can't read anything, it means there's infinite resistance and there's no electrical connection between the two points you're probing.

I covered the whole cavity, including the back of the cavity cover, as well as the pickup cavities underneath the pickups (but not on the sides, due to the tight tolerance). I then ran grounding wire from the pickup cavities to the newly shielded control cavity and soldered on both sides. I kept the Warwick/MEC volume and blend pots, but changed out the others due to the OBP-3's requirements. I attached a physical connection from the copper foil tape shield to the sleeve of the output jack to ground the whole thing, and checking again for continuity, everything showed less than .2 Ohms between all pots and any point in the control and pickup cavities. This makes the grounding wire that Warwick runs from pot to pot redundant, and potentially a bad thing in that it could lead to ground loops since we would have grounding in parallel, so I removed those (prior to testing as I just mentioned, actually).

The bass is now dead silent when not touching/playing it. The effect of doing all this shielding is that you build what's called a Faraday Cage around all your sensitive electronic components, which acts kind of like an antenna for external signals. But when you ground that whole cage that's surrounding all your stuff, you're grounding out all the frequencies and external things the antenna might pick up, leaving you with just that Warwick tone that you love so much!! I'm pretty happy with the results :)

Loving this new bass, by the way!
 

Florin

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Hi guys,

This is not an issue of what strings you use (primarily), and whether they're coated or not.

If the strings are coated then we have a grounding issue :) BTW, never happened this on EMP coated strings.
 
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If the strings are coated then we have a grounding issue :)

You're right because if you have to touch the bridge to ground it, then the bass doesn't ground itself and needs to feed the signal through your body and feet to reach ground. ;)

In my opinion, it is much better to have a properly shielded/grounded bass than to rely on yourself touching the strings as the hum doesn't go in and out as you play - the only thing that is heard is a tasty Warwick tone.
 

Sean Fairchild

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There is some truth there, Florin - although I imagine that the metal ball ends of those strings may not be coated, so when making contact with what should be a grounded tail piece, it should ground the strings. That being said, I believe when I took my LX apart it was the bridge itself, and not the separate tail piece, that had the ground wire running to it. If that's the case, and one uses coated strings, I guess there wouldn't be any physical contact between grounded elements and the non-coated ball end of the string, and the strings may pick up some interference. It would be easy to test to see if the ball ends of the coated strings are conductive and could be grounded by physically coupling the tailpiece and the grounded bridge assembly with something metal (while not touching it) to see if the buzz/hum then goes away.

But the shielding, or lack thereof, of the pickup cavities and control cavity will have a much larger impact I think on whether or not the bass shows poor-grounding hum or poorly-shielded buzz. I wonder, if the bass were shielded and grounded correctly, if the extra noise would go away even when using coated strings. Sadly, I don't have any to try!
 
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I could have sworn DR coated strings had conductive coating. I thought they were the only ones, too.
 
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I wonder, if the bass were shielded and grounded correctly, if the extra noise would go away even when using coated strings?

It does. On my fretless jazz, that was properly grounded/shielded, I used thick, black nylon coated Labella tapewounds and there was hum at all (when the pickups were at equal volume of course), whether I touched the strings or not. The same was true if I touched the bridge or not.
 
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