In Reply to: RE: Driving Sound Labs with Atma's posted by throwback on June 14, 2012 at 07:51:54:
It doesn't tell much to say that you are getting "lower readings than anyone else", since I am the only one I know who has actually posted data on line. (I believe you posted only SP levels vs frequency on SLOG.) If your readings are lower than mine, it is quite possibly due to the fact that Dr. West was lately experimenting with a new highly resistive coating on the membrane. My speakers were built probably last summer. But anyway, I don't know what readings you are actually getting, so I cannot judge. If you take a look at my data you will see that above 2kHz, even my speakers are 4 ohms and below. One thing that might help, if needed at all, is to reduce the bias voltage below the threshold level recommended by SL. I believe that Z will be to a degree inversely proportional to bias voltage. (I don't actually know this, but it stands to reason, since with no bias V the impedance would probably be infinite.) Anyway, of course first you need to replace those bad tubes, and like Tyu says, run the filaments for several days before applying B+.
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Follow Ups
- What are your readings? - Lew 08:24:10 06/14/12 (8)
- RE: What are your readings? - throwback 11:12:38 06/14/12 (7)
- RE: What are your readings? - Lew 11:42:53 06/15/12 (1)
- RE: What are your readings? - throwback 16:16:42 06/15/12 (0)
- RE: What are your readings? - Ralph 08:29:06 06/15/12 (4)
- RE: What are your readings? - Lew 11:47:26 06/15/12 (3)
- RE: What are your readings? - throwback 16:18:51 06/15/12 (0)
- yes, I don't doubt that it rolls off - Ralph 12:15:44 06/15/12 (1)
- RE: yes, I don't doubt that it rolls off - Lew 14:30:02 06/15/12 (0)