I have just bought a BAT VK5se preamp for good deal.
What I have found is the plate resistor being abnormally low value for the parallel 2 section of 6h30. The plate R of 6h30 per section shown in EH datasheet is 840 ohm per section then parallel 2 section is 420 ohm.
However the plate resistor is only 1250 ohm which is less than 3 times of 420 parallel section of 6h30. Is it normal for high priced preamp design?
Apart from smaller gain, does the small R value of plate load resistor affect the dynamic of preamp which is my major concern.
The B+ is 138V and the plate volt is measured as 80V idle running 22mA per section. It means I can have 58V to play with CCS if I remove plate resistor and put in place the CCS.
What sonic improvement I will get if I use CCS, and what type CCS do you recommend?
This post is made possible by the generous support of people like you and our sponsors:
Topic - Too low plate R value for a triode ? and CCS substitution? - Eric Chan 07:09:42 03/22/17 (12)
- RE: Too low plate R value for a triode ? and CCS substitution? - Tre' 21:53:47 03/22/17 (4)
- RE: Too low plate R value for a triode ? and CCS substitution? - Eric Chan 23:10:51 03/22/17 (3)
- RE: Too low plate R value for a triode ? and CCS substitution? - Tre' 07:59:11 03/23/17 (2)
- RE: Too low plate R value for a triode ? and CCS substitution? - dave slagle 10:28:53 03/23/17 (1)
- RE: Too low plate R value for a triode ? and CCS substitution? - Tre' 13:25:27 03/23/17 (0)
- RE: Too low plate R value for a triode ? and CCS substitution? - Eli Duttman 08:16:41 03/22/17 (6)
- RE: Too low plate R value for a triode ? and CCS substitution? - Eric Chan 08:53:34 03/22/17 (5)
- RE: Too low plate R value for a triode ? and CCS substitution? - Uncle Mike 09:24:01 03/22/17 (4)
- RE: Too low plate R value for a triode ? and CCS substitution? - JKT 10:34:17 03/22/17 (3)
- RE: Too low plate R value for a triode ? and CCS substitution? - JKT 14:26:49 03/27/17 (2)
- RE: Too low plate R value for a triode ? and CCS substitution? - Eric Chan 09:11:40 03/28/17 (1)
- RE: Too low plate R value for a triode ? and CCS substitution? - JKT 12:18:56 03/28/17 (0)