Although there are a few threads that deal with the L'espressivo (formerly known as less-pressivo) design by dsavitsk, I thought that a single thread would not be a bad idea (and I have some questions to ask, sorry :p ). I am not going to recall its history since dsavitsk did it on his website : ecpaudio.com (see L'espressivo Project -- Parafeed Spud Amplifiers for Headphones)
The schematic (click on it to see the build page)
(tube used here is 7KY6, output transformer is Speco T-7010, Q1A is 10M45)
If this was to become a semi-official build thread, I would gladly update its informations.
Now for my questions :
How are we supposed to understand the heater supply ? When I use triodes, I make sure that heater is around the same potential as cathode, here it doesn't seem to be the case. I would say heaters are at 20V whereas cathode is at 2V. Is it this way because the 7KY6 is a pentode ?
How can I modify the CCS ? I put together a BOM for this project, using as few shops as I could to cut down on shipping. I am currently planning to buy from Alliedelec, antique electronic supply and the local suppliers. But if I want to use 10M45 or DN2540, I have to order from Mouser. I saw the Torpedo schematic (you can go here : http://www.diyforums.org/Torpedo/TORPEDOschematic.php ) and thought that I could use this kind of bipolar based constant current source (with R7/R9 going to ground instead of the cathode). I can get MJE350 localy, and it adds four LEDs, so more glowing for me
Thats all !