DC DARLING
This is not so much a reply to this thread but an obseravtion (!) I built one of these amps. a few years ago and had been regularly using it until about a year ago when I needed a more powerfull amp. and built a DC coupled 6B4G design. Recently I've built a Full range speaker and decided to see how the DC Darling would work. It works fine! However, I thought I'd best check it over as it had been out of use for some time. What I discovered was a bit of a revelation! Due to an error of construction (mine!) I had doubled the Ia of the 1626's to 50mA each! As they had been running like this for a couple of years with no problems, (No overheating or red anodes!) I wondered if anyone else had run these particular valves like this and what effects they may have noticed? I'm not recommending this mode of operation but am suprised how little effect on their life and performance there appears to be, after all, they are rated at 5W dissipation and 25mA Ia. (Not 50mA and 15W as I'm doing!).
Something to think about!
Regards,
David.