General 5e3 circuit question

[bgood]

Hi,

I've just finished the Dave Hunter book and for those familiar, he takes the reader through a narrative on what is happening inside a Princeton. I'm looking for something similar but for a 5E3 so I can study it. Can anyone point me to some very descriptive info about how the signal works through this amp? I sort of get it but I'm wondering some things. Caution - I'm new to this so I may be asking lame quesitons.

1. When the signal leaves the 12AX7 at pins 6 and 8 it goes into the power tubes and finally the OT.

I'm thinking that this signal needs to be out of phase so it can be amplified by each 6v6GT seperately. Is that right and if so, when does it get out of phase? Does coming off the plate and the cathode of the 12AX7 give it an out of phase signal? Do I even have that right?

Does this make any sense? LOL. I just finished my first DIY build and I am totally into learning as much as I can. The build came out great (Guytronix Gilmore Jr.) and I learned alot but I'm trying to understand more. I have also downloaded and printed the Jack Darr book (thanks to one of you guys here). I just don't have any background in this stuff to work off of.

Thanks to anyone who helps with a response.

Bob

[stokes]

"I'm thinking that this signal needs to be out of phase so it can be amplified by each 6v6GT seperately. Is that right and if so, when does it get out of phase? Does coming off the plate and the cathode of the 12AX7 give it an out of phase signal? Do I even have that right?"
Yes,the plate and cathode of that stage are out of phase,hence the name "phase inverter".Check out www.aikenamps.com there are some good references for different stages in amps,including the phase inverter.

[bgood]

Thanks

[Bruce / Mission Amps]

Thanks

Adding to the Stokes reply,
remember that a cathode in the triode follows the grid and the plate is 180 degrees out of phase with the grid.
This is where the push pull term comes from.

A cathode follower is called that because it follows the grid in phase.

The lower section of the PI driver is a cathode follower and also very low impedance, under 1000 ohms, while the plate section is probably closer to 35,000 ohms.
This effects how much drive is actually available from the cathode vs the plate side.
If a cathodyne driver is built correctly and well balanced side to side...and you do not drive the PI into distortion, it is an excellent phase inverter but it has no gain and actually has a small amount of loss.
That's why the triode in front of it is running flat out... it actually is the gain stage that is driving the high voltage swing to the power tubes.
If you measure the output of that gain triode, you'll note that it is almost exactly the same AC voltage that appears on the grids of the power tubes.
Since the 6V6 power tubes are cathode biased and don't really need more then around 25-30vac signal on the grids to turn on fully, it is not required to do any more then that.. but it can
If you increase the plate voltage of those two, you can get quite a bit more signal voltage swing on the grids of the power tubes.

Other tubes, like 6L6s, KT66, EL34s etc etc... might need more signal on their grids to develop full power (especially if fixed bias)... and that was a hint.

[dobsont]

I like your question -- I'm at about the same place as you, save that I have not read either of these books. Thanks for mentioning them -- now I'll have to see if I can find them.

cheers!

[bgood]

Appreciate that detail - thanks again

dobsont - that Hunter book is avail at Amazon. the Dar book is online - just do search on Jack Darr Amplifier. You'll find it. I believe it's out of print.

So much of this stuff is way over my head it's hard to get any traction but doing a first build helped alot and there's a lifetime of stuff to learn. Have fun.

[TD_Madden]

Actually, the Darr book is back in print and should also be available.

[tubeswell]

Jack Darr Book

Someone posted a link on one of these posts a few weeks back which I found useful. Here it is again

http://www.pacificrecone.com/JackDarrBook.html