Here's an interesting Philips book. See especially pages 10 and further for the use of either EBL21 and ECH21 in PP applications. Also interesting pages 178 and further regarding the ECH4, the ECH21's predecessor with the same data.
As I said above, where are the objections against using a variable µ tube in AF services if even Philips advised so?
Best regards!
As I said above, where are the objections against using a variable µ tube in AF services if even Philips advised so?
Best regards!
In this thread nobody wrote that there are always objections against using vari mu tubes for audio purposes.
TS didn't mention wanting an automatic level control or something like that in his amplifier. He did however express that he wanted a high quality design. That's why I advised against using an ECH21 or EF22 in his amplifier. There are better choices distortion wise.
Philips at the time didn't have much better than the ECH4/ECH21 for phase splitter if they didn't want to use a transformer. When the ECC40 became available, that changed.
Remarkable that earlier you seemed to have some reservations when it came to using vari mu (like) tubes for audio yourself too:
https://www.diyaudio.com/forums/tubes-valves/203734-special-signal-tv-tubes-2.html#post2846991
Are PCF80 and PCF86 any good for tube amps?
TS didn't mention wanting an automatic level control or something like that in his amplifier. He did however express that he wanted a high quality design. That's why I advised against using an ECH21 or EF22 in his amplifier. There are better choices distortion wise.
Philips at the time didn't have much better than the ECH4/ECH21 for phase splitter if they didn't want to use a transformer. When the ECC40 became available, that changed.
Remarkable that earlier you seemed to have some reservations when it came to using vari mu (like) tubes for audio yourself too:
https://www.diyaudio.com/forums/tubes-valves/203734-special-signal-tv-tubes-2.html#post2846991
Are PCF80 and PCF86 any good for tube amps?
I was looking around for a schematic for the EBL21 too. I am building a Baby Huey using loctal tubes and just wanted to confirm a suitable operating point. It looks like if I decide on individual cathode bias then 270R and 300V B+ are a good choice. The amp will be in pentode mode, so it looks fine to tie the screen to B+ on the centre tap of the OPT. Any experience of this tube would be interesting! The more I look at it, it looks like an EL84, but better (more output power for example).
No, the EBL21 surely isn't a better tube than the more recent EL84, and you can't draw more output power from it. Although it's plate dissipation rating is 11 watts, you might want to look for schematics using 9 watt tubes like AL4, EL3, EL11, EL41, which share the same data.
Best regards!
Best regards!