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In Reply to: Here is the operating point for V2a posted by Tre' on April 18, 2007 at 10:43:31:
Tre',
The Eico designers probably used 40 VDC on the plate ( at .83 mA. ) draw for the intermediate stage ( 12AU7, line ) because they wanted to not stress the tubes.WE find many HF-81s with the original Mullard tubes in them, sounding good in 2007, when they were originally installed in about 1959. Thats pretty good, 48 years with original Mullard tubes.
How many of our current designs will do that after 48 years??
Follow Ups:
Not stress the tubes by running 12AU7 with 40 VDC on the plate and drawing 0.83 mA? There is no logic in this. The 12AU7 has poor linearity to start with, but under those conditions it has no chance. I can hardly believe EICO would do that but, since they evidently did, I'm sure it can't have been to minimize stress on the tube. Have a look at RDH 4 and you'll see what I mean.I haven't 'missed the boat' at all, I was commenting on the HF-81, not your wiring experiments. I have no comment to make on the use of 10 or 12 gauge wire for signal conductors because I haven't tried it. I think you might do better, though, if you were to use a better amp to start with.
If it was anyone other than you, Jeff, I might take offence at your accusations; however, I know you well enough by now to realize that you hold passionate beliefs and sometimes show strong emotions in defence of them.
Ray, Jeff doesn't know a good operating point from a bad one and he won't look at the RDH4 because he thinks it's "a piece of crap" (His words, not mine)I'm afraid there is no hope for Jeff.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I was fully-versed and doing load line analysis, graphical, at a very high level, without the help of RDH4, before you ever finished high school Tre'.
Jeff, using our age to try to win arguments is out of line. You and I are of approximately the same age, but we are always civil to one another and we manage to avoid any ad hominem attacks, don't we? I started my dabbling in audio 50 years ago but I will never admit it, especially on a public fiorum such as this. I'm hoping to be able to hide my own Easter eggs next year (it didn't work this year). What was this thread about anyway?
If that is true then why would you use a 12au7 at 40 volts and .8ma?Jeff, how old are you? So old you forgot? You have claimed, in the past, not to know or understand how electronics work. You are a very confused person Jeff. I am starting to feel very sorry for you. I hope when I get old I don't lose it the you have. It must be a terrible thing.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
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