http://www.tubebooks.org/file_downloads/chicago_100W_amp.pdf
I have all the parts to build it in triode mode. Power supply is done (choke input 530vdc). Fall/winter project. Any comments/suggestions welcome!
I have all the parts to build it in triode mode. Power supply is done (choke input 530vdc). Fall/winter project. Any comments/suggestions welcome!
530 volts in triode mode will make most new production KT88 / 6550 tubes very unhappy, though you might get away with this much B+ with cathode bias.
Many builders say that you can bend the screen grid rating in triode mode, but the tubes don't know what mode they are in, and sitting idle with 500+ volts on the screen may invite a runaway on some tubes.
Real GE6550's may be the exception, but I trust mine to 450 volts in triode, and with a 3300 ohm load, I get 75 watts.
YouTube
Many builders say that you can bend the screen grid rating in triode mode, but the tubes don't know what mode they are in, and sitting idle with 500+ volts on the screen may invite a runaway on some tubes.
Real GE6550's may be the exception, but I trust mine to 450 volts in triode, and with a 3300 ohm load, I get 75 watts.
YouTube
Let us know where you (we) can get the original output transformers. That is one of the key factors. I did not know if they are still available.
I can use a bucking transformer to lower the B+ as the HV is from a separate transformer.
I've had the BO-14 outputs for some time and have no idea where more would be available. I'm set on using 5687's as a driver, but I am thinking of using 6dj8 as a voltage amp biased with LED's. I could use a schematic showing how to implement this. Any thoughts??
I've had the BO-14 outputs for some time and have no idea where more would be available. I'm set on using 5687's as a driver, but I am thinking of using 6dj8 as a voltage amp biased with LED's. I could use a schematic showing how to implement this. Any thoughts??