In Reply to: RE: Poor Design for a Preamp posted by Tre' on February 16, 2025 at 12:57:28:
"You can't drive into a 43 ohm load to ground with a stage that has a 8.3k output impedance. . . . 8.3k output wants to see a 83k load."
OK, so in the case of this 01A preamp, he could use a voltage divider with 68k in series and 22k to ground. This would reduce the voltage about the same as the 330k/100k combo he's using and it would present a load of 90k to the tube and be no problem.
The value of 68k || 22k is 16.62k. If we plug that into the low pass calculator then the -3db point would be 54.75k. That should also not be an issue, right?
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Follow Ups
- RE: Poor Design for a Preamp - FlaCharlie 14:34:32 02/16/25 (15)
- RE: Poor Design for a Preamp - Tre' 15:22:32 02/16/25 (14)
- RE: Poor Design for a Preamp - mwhouston 19:58:38 02/16/25 (13)
- Yes, with DHTs hum can be an issue - Tre' 20:29:51 02/16/25 (12)
- RE: Yes, with DHTs hum can be an issue - mwhouston 20:34:15 02/16/25 (11)
- RE: Yes, with DHTs hum can be an issue - Tre' 20:39:48 02/16/25 (10)
- RE: Yes, with DHTs hum can be an issue - mwhouston 03:48:34 02/26/25 (2)
- RE: Yes, with DHTs hum can be an issue - FlaCharlie 06:32:38 02/26/25 (1)
- RE: Yes, with DHTs hum can be an issue - mwhouston 13:32:24 02/26/25 (0)
- RE: Yes, with DHTs hum can be an issue - mwhouston 20:51:24 02/16/25 (6)
- RE: Yes, with DHTs hum can be an issue - Tre' 21:37:40 02/16/25 (5)
- RE: Yes, with DHTs hum can be an issue - FlaCharlie 07:45:40 02/17/25 (4)
- RE: Yes, with DHTs hum can be an issue - mwhouston 16:42:17 02/19/25 (0)
- Those are all good ideas but... - Tre' 09:06:57 02/17/25 (2)
- RE: Those are all good ideas but... - mwhouston 13:50:02 02/20/25 (1)
- "I tried for months but to no avail." - Tre' 18:16:22 02/20/25 (0)