Has anybody build a TT Lummerland with 2xel84 output tubes? I would like to keep the same cathodyne phase inverter (2x12ax7 and a 2xel84)

I am going to change de power supply section with more nodes for a better filtering but what changes should be done in the phase inverter section to feed the 2xel84? And in the conjuntive filter?

Thank you in advance.

Best regards.

It seems Lummerland is based on blues express but the phase inverter looks different.

Hi,

a 18 Watt version with 2 x 6V6 will be available soon.

Best regards, Dirk

Zitat von: Dirk am Jul 11, 2020, 11:27
Hi,

a 18 Watt version with 2 x 6V6 will be available soon.

Best regards, Dirk

Great news!! :topjob:

Hier schon mal ein Bild vom Bub

Zitat von: Dirk am Jul 13, 2020, 04:02
Hier schon mal ein Bild vom Bub

Stark, bin gespannt! Mit NFB?

2x6v6 Lummerland is here!

What is the purpose of R14(220k) in the phase inverter of the LummerLand? This resistor don´t exist in the original Blues Express el84 desing.
It´s the first time I see that resistor in a cathodyne phase inverter and I am curious about it.
Maybe it attenuates the signal before de push pull triodes? because the original desing use pentode tubes and not triode....

R14 provides the grid of the cathodyne with a (self-adjusting) bias voltage. Typically the value would be 470k to 1M. Indeed, I would have guessed that the values of R14 and R28 are actually swapped. This would yield a more typical setup but to be honest I'm not very familiar with those small dual-triode push-pull stages and I'm sure Dirk knows his stuff  :topjob:

Ah! the r28 acts like a grid stopper for prevent blocking distortion in that desing, and maybe de r14 has been lowered to 220k for match with the push pull triode power section.

Thanks!