A tube bias question (or maybe not?)

Tubes Asylum

Questions about tubes and gear that glows. FAQ

I purchased a Jolida 502P amp as an experiment back in January for use with my Magneplanars (1.7's) and it has been absolutely wonderful. Love the sound and much to my surprise my very powerful SS amp (CJ) is not seeing much use these days.

Now to my question. The amp has Tungsol 6550 power tubes and being that I am a tube newby I check the bias every couple of weeks or so. Three of the tubes have held rock steady bias - never varies - 500 mv all the time. One of the tubes tends to very slowly drift down to maybe 495 mv, then I tweek it up to 500mv and then maybe a month latter it's back down to 495 or so. What causes this? is it the tube? is it normal, is it anything to worry about?

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Topic - A tube bias question (or maybe not?) - ejman 17:01:02 06/20/14 (8)

RE: A tube bias question (or maybe not?) - kkak66 13:43:31 06/22/14 (0)

RE: A tube bias question (or maybe not?) - Tre' 21:33:51 06/20/14 (6)

RE: A tube bias question (or maybe not?) - ejman 20:32:56 06/21/14 (5)

RE: A tube bias question (or maybe not?) - ahendler 21:56:10 06/21/14 (4)

RE: A tube bias question (or maybe not?) - Lee of Omaha 10:56:32 06/22/14 (0)

RE: A tube bias question (or maybe not?) - ejman 08:06:47 06/22/14 (2)

As you have an adjustment for each tube try swapping the problem tube... - DeKay 09:58:53 06/22/14 (0)

RE: A tube bias question (or maybe not?) - ahendler 08:55:11 06/22/14 (0)

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