RE: TubeAcolyte ---- 400PS

Posted by Jim McShane (D) on September 5, 2012 at 10:47:53

In Reply to: RE: TubeAcolyte ---- 400PS posted by Chris O on September 5, 2012 at 08:31:19:

"Even in the day these were "special" tubes that were specifically graded by Fender."

Hmmm, I am not sure that is the case. Can you give me a reference to support that?

The reason is I sold close to 1000 1980s vintage GE 6550As and MANY went to 400PS owners. These were not specially selected tubes, just standard production models I ran in and tested/matched carefully. I had almost zero failures and none from the field.

Also, 700 volts and 150 ma. is 105 watts. Not even a GE could take that. Fender's schema showed a bias spec of 210 ma. Ip for all tubes, which computes to 35 ma per tube at idle. So even if there was 700 volts across the tube (IIRC there is some voltage on the cathodes too, and the B+ sags to about 630 volts at full output) that would only be 25 watts.

There is more going on than just evaluating dissipation at idle. But the tubes AFAIK were just regular GE 6550As - they may have been relabeled Fender but that doesn't necessarily mean specially selected. Rich (Koerner) has never mentioned it either, and we've spoken for HOURS about the 400, especially when I had GE stock and he was sending his 400 owners to me. He found what I sent out to be right on target.

So if you can correct my thinking on that please do. In any case it's quite a piece of work, definitely fun to talk about!!

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Follow Ups Full Thread

Topic - TubeAcolyte ---- 400PS - FenderLover 18:25:29 09/04/12 (24)

RE: TubeAcolyte ---- 400PS - perceptiveengineering 23:21:04 09/06/12 (8)

RE: TubeAcolyte ---- 400PS - TubeAcolyte 10:31:44 09/10/12 (3)

RE: TubeAcolyte ---- 400PS - perceptiveengineering 22:36:24 09/10/12 (2)

RE: TubeAcolyte ---- 400PS - TubeAcolyte 09:38:30 09/11/12 (1)

RE: TubeAcolyte ---- 400PS - perceptiveengineering 21:37:22 09/13/12 (0)

RE: TubeAcolyte ---- 400PS - perceptiveengineering 18:13:28 09/08/12 (0)

RE: TubeAcolyte ---- 400PS - TrustYourEars 19:31:52 09/07/12 (1)

RE: TubeAcolyte ---- 400PS - perceptiveengineering 18:00:48 09/08/12 (0)

Heritage! thats funny.... - hennfarm 07:58:49 09/07/12 (0)

RE: TubeAcolyte ---- 400PS - Chris O 08:31:19 09/05/12 (14)

RE: TubeAcolyte ---- 400PS - Jim McShane 10:47:53 09/05/12 (6)

RE: TubeAcolyte ---- 400PS - Chris O 13:57:04 09/05/12 (5)

Special Design 010309 - FenderLover 18:11:01 09/05/12 (1)

RE: Special Design 010309 - Jim McShane 18:56:58 09/05/12 (0)

RE: TubeAcolyte ---- 400PS - Jim McShane 15:45:26 09/05/12 (2)

Love them original Tung Sol 6550 and GE 6550A! - Chris O 16:37:31 09/05/12 (1)

RE: Love them original Tung Sol 6550 and GE 6550A! - Jim McShane 17:39:53 09/05/12 (0)

RE: TubeAcolyte ---- 400PS - TubeAcolyte 09:15:50 09/05/12 (6)

Tubes - Chris O 09:27:33 09/05/12 (5)

RE: Tubes - Jim McShane 10:19:32 09/05/12 (4)

RE: Tubes - perceptiveengineering 23:16:08 09/10/12 (1)

RE: Tubes - Jim McShane 08:07:01 09/11/12 (0)

RE: Tubes - Chris O 13:46:23 09/05/12 (1)

Wonder what the current swing is, in this amp? - FenderLover 18:14:19 09/05/12 (0)

Follow Ups

RE: TubeAcolyte ---- 400PS - Jim McShane 10:47:53 09/05/12 (6)

RE: TubeAcolyte ---- 400PS - Chris O 13:57:04 09/05/12 (5)

Special Design 010309 - FenderLover 18:11:01 09/05/12 (1)

RE: Special Design 010309 - Jim McShane 18:56:58 09/05/12 (0)

RE: TubeAcolyte ---- 400PS - Jim McShane 15:45:26 09/05/12 (2)

Love them original Tung Sol 6550 and GE 6550A! - Chris O 16:37:31 09/05/12 (1)

RE: Love them original Tung Sol 6550 and GE 6550A! - Jim McShane 17:39:53 09/05/12 (0)

RE: TubeAcolyte ---- 400PS

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