In Reply to: Primarily to keep the tube from running away posted by Chip647 on September 9, 2019 at 05:13:27:
Everything Chip says is 100% correct.As long as you have provided an adequate load for V1, and as long as your coupling cap is of a reasonable value; I've found that tubes generally sound better with lower grid resistor values. [This is one of the primary reasons that grid chokes perform so well.]
My rule of thumb for 'adequate load' is 20 times the preceding stage. The 6N1P's plate resistance is 4k4 - in parallel with the 47k plate resistor, we see a net resistance of 4k032. 20 times that is 80k64. So, you could probably reduce your R(g) to 82k.
But: for full-range response, 82k would require a coupling cap of at least 0.388 uf. Because I like to keep my coupling caps at 0.22 uf or smaller (whenever possible), AND because you already have an 0.22 uf installed, I suggested 150k.
FWIW: an R(g) of 82k with a 0.22 uf coupling cap moves the knee to 8.8 Hz. Depending upon your OPT and system you might never be aware of any low frequency phase shift.
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Follow Ups
- more - Jim Dowdy 09/9/1917:15:55 09/9/19 (10)
- RE: more - Paul Joppa 21:02:21 09/9/19 (0)
- RE: more - vinnie2 19:12:39 09/9/19 (8)
- problems? - Jim Dowdy 20:10:59 09/9/19 (7)
- RE: problems? - PakProtector 17:01:29 09/10/19 (0)
- RE: problems? - vinnie2 03:46:03 09/10/19 (5)
- RE: problems? - Lew 15:08:54 09/11/19 (4)
- RE: problems? - vinnie2 15:17:44 09/11/19 (3)
- K40 is not TFE - PakProtector 10:02:42 09/12/19 (0)
- while you're at it - Jim Dowdy 07:24:30 09/12/19 (1)
- RE: while you're at it - vinnie2 07:43:02 09/12/19 (0)