Bottlehead Forum

General Category => General Discussion => Topic started by: tsingle999 on May 13, 2013, 07:05:35 AM

Title: Hum
Post by: tsingle999 on May 13, 2013, 07:05:35 AM

I have a hum that seems to follow the 45 tube. Its louder than normal hum. Is it a bad tube?

Title: Re: Hum
Post by: galyons on May 13, 2013, 08:09:09 AM

Quote from: tsingle999 on May 13, 2013, 07:05:35 AM

...hum that seems to follow the 45 tube.

Sadly, most likely it is the tube!
Cheers,
Geary

Title: Re: Hum
Post by: Paul Joppa on May 13, 2013, 09:38:47 AM

The hum pot exists because tubes vary from one to another. But if you cannot get rid of the hum with the hum pot, then it's most likely the tube.

Title: Re: Hum
Post by: tsingle999 on May 13, 2013, 10:14:07 AM

Ouch! The hum pot doesn't affect it. Ok thanks guys!
Its a Vaic vv45. Theres no issues using it with the sr45?
Filament voltage 2.5, filament current 7.35 amps, grid voltage 42
Ug and gm tested at ia 50 ma and ua 280 volts..

Title: Re: Hum
Post by: Paul Joppa on May 13, 2013, 11:05:07 AM

Hope that 7.35 amps is a typo! Should not be any issues, except to check that the power line voltage is close to 120v.