Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Twanger on August 03, 2010, 09:14:11 am

Title: volume issue
Post by: Twanger on August 03, 2010, 09:14:11 am

Hi All,

been a long time since i posted!!!!

im back to my old hobby !  im currently flipping an old build of mine (low powered tweed twin) and i have an issue wich i known was discussed here before but i cant find the old post...

here is my problem,. even with the control set at 0 (volume) im still getting plenty of sound coming from the amp, i seem to remember this being an issue on some marshall but i dont remember the fix.

as usual your help will be greatly apreciated!

Thanks
John

Title: Re: volume issue
Post by: jjasilli on August 03, 2010, 09:23:45 am

Is your vol pot grounded?

Title: Re: volume issue
Post by: Twanger on August 03, 2010, 09:38:40 am

yes it's grounded

but im guilty of not having tested the connection, will do that first thing when i get home, i feel rusty, this should have been the first thing i should have checked.

Thanks

john

Title: Re: volume issue
Post by: Twanger on August 03, 2010, 03:53:49 pm

ground is good...

Title: Re: volume issue
Post by: phsyconoodler on August 03, 2010, 04:28:16 pm

 Well,use your noggin' some more.Where does the volume control go to?The grid of the tube,right?So measure the resistance of the pot when it's off from ground to the middle lug.More than zero ohms?Then the pot is to blame.
  Remove V1.Still happens?Then it's the pot.No?Then there is a bleed between channels.
There is a coupling cap connected to the volume of the normal channel that may make it bleed.