Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jerrydyer on May 25, 2010, 02:54:33 pm

Title: AC 30 type help?
Post by: jerrydyer on May 25, 2010, 02:54:33 pm

Ceriatone liverpull with like a parasitic osillation goin on. Half volme I get a farty type sound a little like blocking distortion but the not doesnt fade it just has lots of breakup (wrong kind) Sheilded only to the first grid. more sheilding /  ?
thanks in advance y'all

Title: Re: AC 30 type help?
Post by: Geezer on May 25, 2010, 03:10:02 pm

Have you done any "chopsticking" to see if you might be able to locate where the problem is occuring?

Title: Re: AC 30 type help?
Post by: Leevi on May 25, 2010, 04:18:42 pm

- the grid stoppers (1.5K resistors) of EL84 must be close to the pins
- check signal wires especially around the PI that the incoming and outgoing wires are not too close to each other
/Leevi

Title: Re: AC 30 type help?
Post by: jerrydyer on May 26, 2010, 11:46:51 am

thank you all. turned out to be a bad ground in two spots.   shipped to wisconsin today. sounded killer. the liverpull is cool.