more unexplained electrical noises

[alyctes]

hi folks

I have a bass which makes a distinct beating noise, at maybe 5 Hz or so?, when I plug it in - but only when I'm touching the strings. The more contact, the louder the noise. Other basses don't do this, with the same amp and lead. If I unplug the bass and hold the free end of the lead, I get the same effect.

I'm guessing this is a bad earth on the bass, and possibly bad shielding. Does that make sense?

Thanks for reading

[hamfist]

That sounds a bit worrying ! Sorry I have no idea how to help though.

Greater minds than mine will chip in I'm sure.

[gelfin]

5Hz seems a bit low to hear for me.

[rmorris]

[quote name='gelfin' timestamp='1379880151' post='2217792'] 5Hz seems a bit low to hear for me. [/quote]

I'm guessing that the OP means there's some sort of audible tick or noise burst that happems a few times a second. As you say 5Hz itself would be inaudible ( though possibly 'feelable' with the subbest of sub bass set ups :-)
Anyway - yes, string / bridge earthing issue makes sense. Basically you are the source of the interference - as when you touch the lead itself it happens. With 'earthed' strings / bridge you're 'earthing' yourself and eliminating ( to a large extent - nothing is perfect ) the noise but if the bass earthing is faulty then you aren't doing that and the strings and your body are a source of noise that can be picked up by the bass pickups and wiring / electronics. The detail depends on the specific pickup and shielding.
So, test for continuity between strings and 'earth' pin of the amp mains connector. If it doesn't indicate continuity then that's very probably the issue. If it does indicate continuity then measure the actual resistance in Ohms. See what he meter reads when leads touched together. Anything more than half a ohm above that is suspect.
Let us know how you get on.

[alyctes]

[quote name='rmorris' timestamp='1379888324' post='2217986']
I'm guessing that the OP means there's some sort of audible tick or noise burst that happems a few times a second. As you say 5Hz itself would be inaudible ( though possibly 'feelable' with the subbest of sub bass set ups :-)
[/quote]
Exactly.

[quote]Anyway - yes, string / bridge earthing issue makes sense. Basically you are the source of the interference - as when you touch the lead itself it happens. With 'earthed' strings / bridge you're 'earthing' yourself and eliminating ( to a large extent - nothing is perfect ) the noise but if the bass earthing is faulty then you aren't doing that and the strings and your body are a source of noise that can be picked up by the bass pickups and wiring / electronics. The detail depends on the specific pickup and shielding.
So, test for continuity between strings and 'earth' pin of the amp mains connector. If it doesn't indicate continuity then that's very probably the issue. If it does indicate continuity then measure the actual resistance in Ohms. See what he meter reads when leads touched together. Anything more than half a ohm above that is suspect.
Let us know how you get on.
[/quote]

Many thanks. I will do that.

Edited September 22, 2013 by alyctes

[rmorris]

And I meant to suggest something about possible source of the noise since general hum and buzz is 50Hz and multiples of that (well where the mains frequency is 50 Hz anyway).
I've had a similar interference at 1Hz which turned out to be the second hand movement on my quartz wristwatch ( you'd think that might have been easier to spot !) and also with a guitarist where we had a noise burst maybe once every 5 to 10 seconds - turned out to be caused by a DVD player in a downstairs room in the house where we were practicing upstairs. God knows if the DVD player actually met EMC standards but don't forget that walls and floors are generally transparent to rf interference.

[JapanAxe]

[quote name='rmorris' timestamp='1379972356' post='2219074']
... and also with a guitarist where we had a noise burst maybe once every 5 to 10 seconds ...
[/quote]
I think you'll find guitarists call that a 'riff'.

Edited September 23, 2013 by JapanAxe

[Mr. Foxen]

Wristwatch will do that, the ticks as it turns.

[rmorris]

yeah - I had it with a particular watch. Never noticed it on a bass but did on a single coil pickups Strat type Ibanez guitar. Maybe higher Z pickups ?

[alyctes]

Thank you all, all input welcome