Not necessarily

Posted by Steve O (A) on December 2, 2024 at 15:33:26

In Reply to: I think they just stay 100% on until you turn them off. nt posted by Tre' on December 2, 2024 at 12:52:47:

I worked on a couple of jukebox amps of the 78 and 45 era. Both amps powered down after play was complete. The 78 amp used 100% directly heated tubes and was ready to go from a cold start in a few seconds. The later amp used a directly heated rectifier with indirect 6.3V tubes everywhere else. The heater circuit was dual voltage ~ 10V at cold start which slammed everything up to temp in a few seconds. When the finals (PP 6L6G) began to conduct, a DC relay in the cathode circuit would energize and tap down to 6.3V. Kinda brute force but effective. Tubes were more expendable then.

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Follow Ups Full Thread

Topic - 5R4 GY coke bottle and 5R4 GYA and other 5R4 - John PA 11:17:48 11/27/24 (20)

Unless you are 1kV or more, the tubes could care less about the speed of first B+ - Chip647 14:22:29 12/01/24 (4)

Didn't the old 45 juke box players leave the tube heated. . . - John PA 11:49:42 12/02/24 (3)

I think they just stay 100% on until you turn them off. nt - Tre' 12:52:47 12/02/24 (1)

Not necessarily - Steve O 15:33:26 12/02/24 (0)

Back then, a dime could buy a new one! (nt) - Triode_Kingdom 12:40:16 12/02/24 (0)

RE: 5R4 GY coke bottle and 5R4 GYA and other 5R4 - Tre' 15:48:25 11/27/24 (14)

Yes, but not . . - John PA 17:48:56 11/27/24 (13)

RE: Yes, but not . . - Tre' 19:46:48 11/27/24 (12)

Yes but this is a new. . - John PA 19:57:04 11/27/24 (11)

RE: Yes but this is a new. . - Tre' 08:21:35 11/28/24 (10)

You know, I don't know. . - John PA 12:07:28 11/28/24 (9)

RE: You know, I don't know. . - Triode_Kingdom 15:11:34 11/28/24 (8)

KT170. . . - John PA 21:16:19 11/28/24 (7)

RE: KT170. . . - Triode_Kingdom 08:05:28 11/29/24 (6)

I sent the spec sheets to Cayin. . . - John PA 10:04:27 11/29/24 (5)

RE: I sent the spec sheets to Cayin. . . - Triode_Kingdom 12:46:47 11/29/24 (4)

I was a code specialist but . . - John PA 15:07:13 11/29/24 (3)

RE: I was a code specialist but . . - Triode_Kingdom 20:55:29 11/29/24 (2)

We had teletype but what I meant was that. . . - John PA 08:29:57 11/30/24 (1)

RE: We had teletype but what I meant was that. . . - Triode_Kingdom 09:53:20 11/30/24 (0)

Follow Ups

Not necessarily - Steve O 15:33:26 12/02/24 (0)

Not necessarily

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