• Registered: 2016-03-06
  • Posts: 2

Topic: Silver jubilee issue(hum)

I'm a new owner of the jubilee series amp and I have a hum issue...I was playing the amp in 100 watt mode and everything was great and thought I'd try the 50 watt mode so I flipped the power switch and I got an instant hum,I tried different outlets,cables,unplugging the guitar you name it....it plays in 50 watt mode but there is that annoying hum that's very present even on clean channel,can anyone I relate to this?,,,if it's tubes,pt,etc....thanks for any input

  • DougH
  • DougH
  • BONAMETAL
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  • From: Toronto, Canada
  • Registered: 2011-04-01
  • Posts: 1,700

Re: Silver jubilee issue(hum)

The channels shouldn't matter.. since the High/Low switch is on the output side of the EL34 tubes.

actually I found this quote:

and a High/Low Output switch on the front panel that switches between pentode and triode operation on the EL34s, dropping the power to 50 watts

here is the schematic of the amp
http://www.classictubeamps.com/schemati … w_2555.pdf

looks like the 50/100 switch is connected to T2 choke in high and looks like in low you're coming off of T3 transformer.

maybe you have a winding on the T3 transformer gone.

you'll need to get it checked out.

---------------

(If only I had 1% of Joe's guitar talent)
  • RickB
  • RickB
  • BONAMEGAMETAL
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  • From: San Diego
  • Registered: 2009-10-30
  • Posts: 12,198

Re: Silver jubilee issue(hum)

Check the switch. If it is open on low it will hum.
Rick

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