PL Prologue autobias adjustment ...part 2

Tubes Asylum

Questions about tubes and gear that glows. FAQ

So I got a set of used Svetlana 6550C dated 1996 for my prologue four. They sound pretty good but I wanted to adjust the bias to the recommended 400mv. Prior to adjusting the screw, I had around 350mv for all the tubes. To my surprise, I could only get another 1/8 of a turn and could never hit 400mv. So I wonder if its the old tubes or something else? If someone who has done this can tell me how sensitive the pot is and how many turns they could make that would be great.

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Topic - PL Prologue autobias adjustment ...part 2 - rotarius 20:30:21 12/26/15 (8)

RE: PL Prologue autobias adjustment ...part 2 - johns dad 08:07:18 12/28/15 (5)

RE: PL Prologue autobias adjustment ...part 2 - rotarius 09:17:05 12/28/15 (4)

RE: PL Prologue autobias adjustment ...part 2 - johns dad 15:28:47 12/28/15 (3)

RE: PL Prologue autobias adjustment ...part 2 - rotarius 16:21:29 12/28/15 (2)

RE: PL Prologue autobias adjustment ...part 2 - johns dad 16:53:03 12/28/15 (1)

RE: PL Prologue autobias adjustment ...part 2 - rotarius 17:00:15 12/28/15 (0)

RE: PL Prologue autobias adjustment ...part 2 - Chuck Y 07:52:49 12/27/15 (1)

RE: PL Prologue autobias adjustment ...part 2 - rotarius 17:50:38 12/27/15 (0)

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