Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: fossilshark on November 15, 2019, 11:40:15 am

Title: Gremlins
Post by: fossilshark on November 15, 2019, 11:40:15 am
I'm having some issues with my 2204 clone. What would usually cause the master volume not to cut all signal when turned all the way down, squealing when turned up past 2, definitely doesnt sound loud and the standby switch (between the rectifier and B+ line) doesnt cut sound. Any ideas?
Title: Re: Gremlins
Post by: sluckey on November 15, 2019, 11:56:46 am
Wiring errors, poor soldering, poor lead dress, poor layout are always at the top of the list.
Title: Re: Gremlins
Post by: pompeiisneaks on November 15, 2019, 11:57:30 am
Squealing on a new build is often the phase of the PI and the OT are swapped and the Negative Feedback (NFB) becomes Positive Feedback (PFB).  You can quickly test this by detaching the NFB wire and see if it goes away.  If it does then you either need to swap the OT leads on the power tubes, or swap the output of the PI to the power tubes.

As for the MV not shutting off all volume, it's possible the output is much stronger with PFB going on. 

~Phil
Title: Re: Gremlins
Post by: fossilshark on November 15, 2019, 09:25:40 pm
Pomp that solved the squealing. I'm going to contribute the master vol not working and loss of gain to Sluckeys proposal, because those problems persist.