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12B4 as parallel PP output stage?

Posted by andy evans on December 28, 2004 at 11:43:27:
I was just musing about what kind of sound you'd get out of four 12B4 in parallel PP. No doubt very good. It looks like they would need something like 40v bias to give 20mA at around 280v. Mu is about 6. I was also musing about driving them with a cascode arrangement similar to Allen Wright's but using ECC40, which has a useful HK voltage rating of 175v. How does this sound - anybody tried anything like this? I'm assuming a low value a-a OPT, but how low? Andy