Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: G._Hoffman on October 06, 2024, 09:10:37 pm

Title: What is this?
Post by: G._Hoffman on October 06, 2024, 09:10:37 pm

This is the reverb send node (the grid on the Reverb driver stage) on a AB763 kit I built.  1K sine wave.  The clean sine wave is directly out of the function generator.  I'm using a differential probe set to x200 for the signal, but the distortion happens right where I get a howl from the channel.  I assume this kind of distortion isn't normal here?  Everywhere before this, it is dead clean.
https://www.instagram.com/p/DAzioqHNUwK/?utm_source=ig_web_copy_link&igsh=MzRlODBiNWFlZA== (https://www.instagram.com/p/DAzioqHNUwK/?utm_source=ig_web_copy_link&igsh=MzRlODBiNWFlZA==)

Title: Re: What is this?
Post by: shooter on October 07, 2024, 02:32:34 am

probing directly to the grid can cause unexpected results
do the same test at the plate


does it "howl" with reverb off?