Problem hummmmmm!!

[contrabajo]

I have returned to double bass playing after 15 years,yes i am crazy but enjoying it!!
I use a yamaha BBT-500 head and two yamaha single 10 cabinets,my pick up is an underwood.The problem I have is that there is a loud hum when I use the Yamaha gear but through a friends polytone or an old peavey combo I have there is no hum,why is this ?I tried putting a piece of copper wire from the jack input earth to the ball end of the strings but it doesn't help.
PLEASE help this is driving me crazy!!!!

I just would like to say what a great resource this site is for bass players and that if it had been around when I first started I would be a much more informed and better player now!!(well anyway that's my excuse!!)

[BassBod]

I'm not an expert on such things, but I recall the old Fishman p/up used to come with an extra earth wire - and you just twisted it onto one or more of the strings somewhere below the bridge? If the jack socket is metal cased you should be able to solder a wire to the case and that will provide a ground, but it is a bit odd that it doesn't happen with every amp?

Are you playing in the same room with different amps, also are your strings metal?

I'm sure there is an Underwood website - may be worth emailing the maker and describing the problem...

best of luck

BB

[BOD2]

Just a thought ... are you using the different amps in the same room or different rooms ? The reasoning being that here might be something electrically "noisy" that is being picked up in the room where the Yamaha gear is being used.

There's a pinned topic about humming/buzzing in the Repairs/Technical forum that might be of some help.

[steve]

[quote name='BOD2' post='15130' date='Jun 10 2007, 04:27 PM']Just a thought ... are you using the different amps in the same room or different rooms ?[/quote]

I had the same thought, could it be dimmers in the lighting circuits or something similar to do with the environment you're playing in?