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807pp + input phase splitter
807pp + input phase splitter
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Old 12th January 2013, 01:20 PM   #41
lcsaszar is offline lcsaszar  Hungary
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Join Date: Mar 2004
Location: Budapest, Hungary
Is it related to the fact that Vg2=300V, Va=600V max according to the spec sheet, and 300V is too low B+ in triode mode for getting optimum performance?
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Old 17th February 2013, 10:12 AM   #42
6J7 is offline 6J7
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Join Date: Apr 2009
Location: France
Default paraphase ?


I received the silver mica's caps, 100pF to 1nF for the input PI trans (Sowter 8920). It didn't cure the problem, still ringing.. just for testing purpose I tried with a LL1681 (MC input transformer not intended for this use), all is well, no ringing, sinewaves, triangles, even squares are clean.

Now I would like to try an old and simple PI, the paraphase. This one seems to be a little bit different. 1M in // of the 270K and connected to ground through the 270K.

Any comment ? no pot needed to adjust the gain of the second half triode ?

Is this PI dangerous in case of overdriven PP ?

Last question, generally speaking, does a PP triode connected has interest ? every time I tried UL, it sounded better to my ears, despite the DF issue (no feedback yet).

OPT are from Quicksilver mini-mites, good ones ?

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