Kalamazoo Bass 30 Hum machine

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Rafael
Posts: 9
Joined: Thu Mar 06, 2008 7:43 pm

Kalamazoo Bass 30 Hum machine

Post by Rafael »

Working on a '65 Kalamazoo Bass 30 that has the funky flip out control panel. Love the amp, hate the hum: This thing sounds like a bee hive when you turn the volume above 12 oclock. Nice tone, but ugh!

What I'm wondering is if anyone has experience with this amp and reducing the hum and if so, what areas to concentrate: I don't know if it's the fact that the power switch and all the volume/tone controls go in and out of the same multipin connector, or if it's just a bad design, and I need to do something drastic like raise the potential of the heaters, or should they be quiet and I should be looking for a defective component?

Thanks in advance!
Andy Le Blanc
Posts: 2582
Joined: Sat Dec 22, 2007 1:16 am
Location: central Maine

Re: Kalamazoo Bass 30 Hum machine

Post by Andy Le Blanc »

hum can be from many places
short the input to the phase inverter
to see if its still audible in the out put
if it is start working your way thru the amp from
the power supply
if it is not start looking for other reasons
ie: tubes, lifted ground, bad solderjoin, leaky caps, poor contacts, etc....
sometimes in an old amp the insulation in the power transformer
is leaky
and some times the terminal strips or componant board have become comductive
lazymaryamps
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