On the previous post I explored how more power could be extracted from the 45 in class A2. Here is a first draft circuit using the 4P1L as the driver stage with a mu-follower gyrator load to provide current with low output impedance:
3.5W can be obtained with 13Vpp input signal. Clearly a pre-amp is required, but that is the output level I’m currently getting from my preamp so should be fine. The LND150 CCS reference can be optimised and derived from the stable 280V.
Not a bad idea, just an additional power supply to avoid any nasty cap in the path.
Now you just need to make it! :-))
Well, not very encouraged by the results of the 45 in A2 on paper. With a better driver (e.g. 6e5P) it performs slightly better but the dominant distortion is the 45…
There are other good DHTs for A2 though, so will put this one on the project pipeline for the time being 🙂
thanks for all the help
Yeah, I told you the power wouldn’t be so much higher. It’s a small power triode. That’s why I prefer the PP. It’s just as good…. with a lot more energy!
Powerful single ended means 211 for me! 🙂
I will look at PP circuit options for 45/46. Tempted to experiment with some of Rod’s circuits, so will open a thread in DIYaudio over the weekend when I get some time!