ECE4448 L46: Biasing Single-Ended Power Amplifiers (Guitar Amplification and Effects, Georgia Tech) 

Thank you for your kind words!

Thank you for your kind words! I also have playlists for ECE3400: Analog Electronics (which is like this class, but on transistors instead of tubes), and ECE4450: Analog Circuits for Music Synthesis that you might find of interest.

Thanks!

I tell my students that if they ever get under the hood of one of these and need to take a live measurement, make an alligator clip connection and *then* turn on the amp. And after they turn off the amp wait long enough for the bleed resistor do do its thing. :)

@@Lantertronics Good advice. If you do poke around a live one keep one hand behind your back or in your pocket.

Have you watched Uncle Doug? He's a retired math teacher who's got a wonderful dry sense of humor and lots of videos on tube amps. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-L3rRk3eSTnA.html

Of course, there was that one time I was testing a power supply and I saw the alligator clip start to slip... let's just say I'm very glad I used the restroom before conducting the experiment. The flash, the bang, the smell of ozone...

@@Lantertronics Last year I was converting an old AM radio into a bluetooth speaker and made the classic mistake of hooking my scope ground to an old ungrounded circuit (I HAVE and isolation transformer but wasn't using it like a moron.) A very large trace instantly turned into plasma with a bang and left a pretty copper smear on my workbench. Somehow I didn't blow the channel on the scope.

Not at present. Someday if I ever teach our ECE3400 Analog Electronics course again, I might.

The screen grid doesn't really prevent the secondary emission -- and actually the secondary emission always takes place, it's only really a problem in tetrodes because they're attracted to the screen grid. It's the job of the suppressor grid to shove the electrons back towards the plate.

Regarding not using grid stopper, I think you have things backwards... not using a grid stopper is like having R=0 in the 1/(2*pi*R*C) formula which would put the cutoff frequency of the lowpass filter at infinity, letting everything through. Including a grid stop resistor is what creates a lowpass filter via the Miller effect.

@@Lantertronics the grid stop resistors are suppose to filter out the tubes oscillations or other noises which it's not called emf or back emf but tube crease noises that bleed into the grid. I'm not sure why amplifiers would add grid stop resistors because this would be like adding RC low pass filters to each tube stage

@@waynegram8907 It's exactly the lowpass filter effect that stops the parasitic oscillations.

@@Lantertronics right, but why does a tube have parasitic oscillations? I think the miller effect capacitance of the plate to grid capacitance is what is causing the parasitic oscillations?

Yup, the videos are produced by a team of... just me. I've become very fast at using Camtasia.

The square law for power dissipated by a resistor just comes from substituting ohm's law into the P=V*I equation (you can also get P=I^2 R using the same technique).

@@Lantertronics Team Aaron, lol. the editing is awesome, so are the lyrics.

​@@Lantertronics P=I^2 R, grrr. i guess I^2 means I square. Maybe you should make a (if you got time) a recompilation of all the math formula's and notations and where to use them. So i can calculate the LA-2A before i make faulty pcb, meaning having the wrong footprints ... and still is a pretty heavy stuff around the "side chain", R3, R37, weird is C12, i wouldn't know how to solve that one. Since i suspect around 290 V DC from my PSU, maybe this R35(220K) and R38 (22K) voltage divider is wrong, since you need to feed 100V in to the plate of the tube. the Function of C13!!! if i sum, R35 (220K) and R38 (22K) = 242000K. 290 V ÷ 242000 R = 0,001198347 Amp. using your formula: (0,001198347×2) × 242000 (P=I^2 R) = 579,999948? Kinda rusty apart from Ohm's law and a bit more. : )

@@AnalogDude_ Thanks!