13-09-2019, 06:16 AM
Edcor do decent cheapish SE OPT's as does Hammond. A good valve to use with a 12k OPT is the QQV03-10, two beam 5w pentodes in one bottle. For class A you can move the load line about a bit, it's best to try and get it through or above the knee, see - http://www.valvewizard.co.uk/pp.html .
Andy.
Andy.
