Modern mass-produced amps need a bit of attention to unleash their true sound potential. This Chinese-made Vox AC10 is one of my favourites. During this video, I will show you how to check the dissipation at idle of the power stage of a Class A amp and we will see why modern manufacturers invariably set the bias too hot, and what we can do to tame them.
If you agree with my partner who glazes over when I start “nerding out”, you can skip to one of these scenes:
3:00 How does Cathode bias work?
6:50 Power supply, Filter Capacitors, and the myth of rectifier Sag
9:45 How to calculate the power dissipation of an EL84 tube
14:50 Kafe and Paximathi
15:30 Matching tubes for Plate current and Transconductance
25:20 Reduce the gain with a 5751 preamp tube
27:00 Reduce the gain even more with a 12AY7 preamp tube
30:00 The Hunt for the Rattle
36:00 The Weber DT10P speaker option
38:00 The Sound Check
BEWARE THE GRIM REAPER: Before you try this on your amp, know that there will be parts of our beloved amp that will be intentionally trying to kill you. Sure, the villains will look innocent enough, but touch them and that foul demon will throw you across the room with deadly force.
PS. If you need your amp repaired in Sydney Australia, give me a call. My details are on my website guitaramptech.com.au/
15 авг 2020
