In Reply to: 813 set schematic posted by vinnie2 on February 10, 2019 at 09:12:26:
Hot diggity dam! Got BOTH the 845 and the 813 amps up and running this morning per the attached schems. I took blackplate's advice and put a capacitor in front of the output tubes and was then able to get things running well. Both amps now sound really good, with the triode connected 813 being particular pleasing. The operating points for 845 are pretty close to those I was trying to hit that Mike Lafevre said were a favorite in Japan. Once I had the 845 running well, I basically just dropped the 813 in it's place with a few changes to accommodate that tube. I have no idea if the operating points of the 813 are considered to be good ones, but when you look at the plate curves for the 813 it seems to be in a pretty linear area.
If anyone has any suggestions on other operating points for the 813, I would like to hear them. These are both easy to build, good sounding amps. The only hassle is the 10-volt filaments. Even then, by using the resistors off of the filament pins to balance out the hum, I am able to use AC voltage on all the filaments with so little hum I have to have my ear right next to a speaker to hear it.
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Follow Ups
- update 2 - vinnie2 11:49:35 02/15/19 (49)
- RE: update 2 - deafbykhorns 03:46:40 02/17/19 (44)
- RE: update 2 - vinnie2 03:59:41 02/17/19 (43)
- RE: update 2 - deafbykhorns 12:14:49 02/17/19 (42)
- RE: update 2 - vinnie2 12:45:09 02/17/19 (41)
- RE: update 2 - deafbykhorns 17:57:09 02/17/19 (40)
- RE: update 2 - vinnie2 13:54:06 02/18/19 (38)
- RE: update 2 - cpotl 16:16:32 02/18/19 (37)
- RE: update 2 - vinnie2 18:14:21 02/18/19 (36)
- RE: update 2 - cpotl 19:57:17 02/18/19 (35)
- RE: update 2 - vinnie2 04:58:32 02/19/19 (34)
- RE: update 2 - cpotl 06:07:46 02/19/19 (0)
- RE: update 2 - cpotl 05:40:56 02/19/19 (32)
- RE: update 2 - vinnie2 07:00:18 02/19/19 (31)
- RE: update 2 - deafbykhorns 15:15:55 02/20/19 (30)
- RE: update 2 - Tre' 10:12:50 02/22/19 (0)
- much better! - vinnie2 06:21:16 02/22/19 (24)
- RE: much better! - cpotl 08:42:38 02/22/19 (23)
- RE: Sample Sine Wave - deafbykhorns 11:28:41 02/22/19 (20)
- 845 op points - vinnie2 06:19:57 02/23/19 (0)
- RE: Sample Sine Wave - vinnie2 05:02:59 02/23/19 (15)
- RE: Sample Sine Wave - deafbykhorns 16:51:37 02/23/19 (14)
- RE: Sample Sine Wave - vinnie2 17:56:28 02/23/19 (13)
- RE: Grid Current - deafbykhorns 14:56:39 02/24/19 (7)
- RE: Grid Current - vinnie2 17:59:00 02/24/19 (6)
- RE: Grid Current - deafbykhorns 06:00:36 02/25/19 (5)
- RE: Grid Current - vinnie2 06:44:26 02/25/19 (4)
- RE: Try the 300B with a good DHT - deafbykhorns 07:54:02 02/25/19 (3)
- RE: Try the 300B with a good DHT - vinnie2 09:19:20 02/25/19 (2)
- RE: Try the 300B with a good DHT - deafbykhorns 13:01:02 02/25/19 (1)
- thanks! nt - vinnie2 13:59:12 02/25/19 (0)
- what are the 6sn7 op points? (nt) - Tre' 06:53:46 02/24/19 (4)
- RE: what are the 6sn7 op points? (nt) - vinnie2 14:45:14 02/24/19 (3)
- RE: what are the 6sn7 op points? (nt) - Tre' 18:02:17 02/25/19 (2)
- RE: what are the 6sn7 op points? (nt) - vinnie2 04:31:51 02/26/19 (1)
- RE: what are the 6sn7 op points? (nt) - cpotl 05:07:07 02/26/19 (0)
- good post (nt) - Tre' 14:06:08 02/22/19 (0)
- RE: Sample Sine Wave - vinnie2 11:40:25 02/22/19 (1)
- RE: Sample Sine Wave - Tre' 14:05:06 02/22/19 (0)
- Good point. - Tre' 10:43:36 02/22/19 (0)
- RE: much better! - vinnie2 09:56:27 02/22/19 (0)
- RE: update 2 - vinnie2 06:23:22 02/21/19 (2)
- RE: Example - deafbykhorns 12:38:17 02/21/19 (0)
- RE: update 2 - cpotl 08:29:18 02/21/19 (0)
- RE: update 2 - vinnie2 17:54:53 02/20/19 (0)
- RE: update 2 - vinnie2 06:45:38 02/18/19 (0)
- my suggestion - Jim Dowdy 12:22:25 02/16/19 (3)
- RE: my suggestion - vinnie2 12:47:58 02/16/19 (2)
- RE: my suggestion - Jim Dowdy 12:59:46 02/16/19 (1)
- RE: my suggestion - vinnie2 04:04:39 02/17/19 (0)