Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Crate50watt on June 23, 2017, 09:16:24 pm

Title: volume goes from 1 to 100 in a tenth of a turn
Post by: Crate50watt on June 23, 2017, 09:16:24 pm

Hey team, i just finished a 18w tmb build. Amp fires up, buzzes a bit and plays. My volume knob goes from nothing to everything in about a tenth of a turn. I mean you barely move it and it almost blows my shitty shop test speaker. Maybe a bad potentiometer? I used dougs schematic and it has a 500k audio pot in there. Also the tone knobs don't appear to be doing much either... Thanks in advance!

Title: Re: volume goes from 1 to 100 in a tenth of a turn
Post by: Raybob on June 24, 2017, 05:28:50 am

Double check your wiring of the tone stack.

Title: Re: volume goes from 1 to 100 in a tenth of a turn
Post by: Tony Bones on June 24, 2017, 09:03:58 am

Not to state the obvious, but it's almost certainly a wiring problem. Check that the appropriate lug on the volume pot is grounded. Check everything around the volume pot. Check everything.

Post photos of your wiring. There are a few guys here that are surprisingly good at finding problems just by looking at photos.

Title: Re: volume goes from 1 to 100 in a tenth of a turn
Post by: jjasilli on June 24, 2017, 10:51:49 am

Also, make sure to use an audio log pot.  Linear taper can cause this issue.

Title: Re: volume goes from 1 to 100 in a tenth of a turn
Post by: Johntb on June 25, 2017, 01:14:56 pm

Some good up close pics would help.