In Reply to: Poor Design for a Preamp posted by Triode_Kingdom on February 16, 2025 at 09:51:58:
Regarding the voltage divider . . . couldn't he just use a 33 ohm in series and a 10 ohm to ground? The voltage reduction would be the same.
The resulting output impedance would then be dominated by the impedance of the tube which, assuming a 50k load resistor, would be 8.33k.
If the formula I posted is correct (??) the output impedance would be:
(8.33k + 33 ohms) + (10 ohms || the assumed 100k input impedance of the amp) = 8363 ohms + 9.99 ohms = 8373 / 8.373k
Looks like this would move the rolloff point to ~108k if only the 175pf capacitance of the cable is included.
Am I missing something?
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Follow Ups
- RE: Poor Design for a Preamp - FlaCharlie 12:17:02 02/16/25 (27)
- RE: Bartola - deafbykhorns 11:08:37 02/17/25 (3)
- I bet that works good - Tre' 13:34:15 02/17/25 (2)
- RE: I bet that works good - Triode_Kingdom 16:48:57 02/17/25 (1)
- Yup! nt - Tre' 17:15:13 02/17/25 (0)
- RE: Poor Design for a Preamp - Tre' 12:57:28 02/16/25 (22)
- RE: Poor Design for a Preamp - mwhouston 17:55:07 02/26/25 (5)
- RE: Poor Design for a Preamp - FlaCharlie 10:19:33 02/27/25 (2)
- RE: Poor Design for a Preamp - mwhouston 14:13:55 02/27/25 (1)
- Metal Tubes / Tube Sources - FlaCharlie 10:43:52 02/28/25 (0)
- Confusion - FlaCharlie 09:50:01 02/27/25 (1)
- RE: Confusion - mwhouston 14:08:29 02/27/25 (0)
- 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)