[LeeH]

Hi All

Recently rolled in a couple of Mullard CV4003 valves into my Mastersound amp. When i switched on the amp I noticed a "rumbling" noise in one of the speakers, never heard this before. I swapped the valves over and the rumbling noise switched sides. Do i have a faulty valve? I did give the amp a play and the music seemed to play ok but its got me a bit concerned.

As a tester i put my old valves back in and the noise disappeared.

Any advice much appreciated

Thanks

Lee

[FullRangeMan]

Seems a defective tube to me. The noise is ''hum''??

Some noise test:
http://www.youtube.com/watch?v=13n1VCR6UXw

[Captainhemo]

I'd agree  especailly being that the noise follows the tube when you switch its position  and it goes away completlly when you   put the old tube back in

-jay

[ltr317]

It may or may not be the valve.  It could be oxidation on the pins of the noisy one.  Use either very fine sandpaper or emery board and clean the pins.  Apply some DeoxIT if you have some after cleaning.   Very often that's all it takes for eliminating the noise.  If the noise is still present after cleaning the pins then the valve is probably defective.