Use of 6528A as power tube

[Paul Joppa]

This project really calls for more information than can fit in a forum post.

I'm sure you can learn a lot about power supply design on the web, including the meaning and effect of transformer regulation.

Less easy is to determine optimum operating points. To over-simplify, those tubes that have a higher transconductance will drive lower impedance phones. But transconductance is itself a function of the operating point. More cathode current will increase the transconductance but creates more heat and may require a new design to replace the Speedball current source. Incidentally "transconductance" is another way of saying "tendency to oscillate" - that's why I referred you to 6C33 design issues.

...

I once took a drawing class, thinking it would be cool to be able to sketch people and places I've seen. I learned two things - it takes a lot of practice and many mistakes, and a drawing takes more than 10 times as long as I had thought. But I still work on it from time to time because it's still rewarding. Same goes for electronic design - it's more work than you think, but it's also more rewarding than you think.

 

[Loon]

Thanks for the encouragement Paul.  This is a hobby that I would like to continue for the rest of my life and that I am only just starting.  It is really helping with my depression issues atm as a kind of diversion therapy.

You have gone above and beyond the call of duty in answering my questions. 

Warm regards and thanks

 

[Paul Birkeland]

I'd recommend buying a piece of plywood, some octal relay sockets, a beefy variable power supply, and Morgan Jones's book on designing tube amps.  There are high voltage supplies around that will give you 100-300V and a few hundred mA if needed.  Some even have a beefy 6.3V supply just to keep you out of trouble. 

Of course, you'll need to sketch circuits and buy the appropriate extra bits to get them running (a few caps and some very large resistors)

You can use those tools to try a whole ton of different things without committing to buying a whole bunch of parts.  If you try 20-30 different designs, odds are that there will be one or two configurations that make enough of an impression on you to move forward.

 

[Loon]

Awesome idea.  I imagine there would be cheap thrills and spills to be had with this set up!  The perfect balance of theory and practice.

 

[Doc B]

That's how I started. Only the original gangstas will remember my frightening breadboards in the basement listening room back on the 90s. As long as you are willing to take full responsibility for the potential hazards of a bunch of clip leads carrying high voltage strung all about it can be kind of a fun way to quickly sketch out a circuit.