My LSES experiment with Edcor 2H/300ma/21 ohm chokes used for input service ended in failure.
I began to notice an odd buzz begin to develop in the L1 choke that sounded like frying bacon , so I pulled the plug on LCLC (L1=L2) LSES filters for fear of damaging a good part.
The 6CB5 finals were running at about 14 watts.
Returned to a flywheel filter: (1) LC section with 35mH/2A/.79 ohm Triad input choke followed by
(2) LCRC section for left/right finals and driver stages.
With this filter, I was able to run about 23 watts on the anode of 6CB5 in triode mode with no audible noise coming from the L1 choke.
Driver stage is ECC83 w/CCS plate load @ 1.5mA. AC heating for all tubes.
Heyboer SE 14W 5K:8 OPT's.
The subjective sound is very powerful on Altec 811B+808-8A/414-8B.
Date : Decemember 7, 2016 from AA Tube DIY Forum
Comments from DT 667 :
Unfortunately, I don't think I took the usual measurement data (THD, bandwidth, phase, etc.) on this circuit before the breadboard was broken down in favor of other projects.
I might want to revisit 6CB5 tubes in the future because they can put out good power in SE triode connected mode and the plate curves look similar to a 300B.