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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: BDT preamp details posted by John Swenson on July 9, 2004 at 00:38:03:
The beam deflection tubes will generally give better linear performance if you demagnetize them using a TV deguassing tool or AC solenoid coil. (Even regular tubes may benefit from this.) They are made using steel sheet parts and become magnetized after sitting on the shelf for 50+ years. These tubes have an effective Mu of around 6 (from the deflection plates) if you use a current source load, less with resistive loading. You can get higher gain by cascoding with a conventional triode or pentode. There were some articles published on using these tubes for audio back in the late 50s and early 60s but they never caught on. They are the only devices which ever had a truly linear response curve (from the deflectors), but do become soft limiting at high signal levels. Another design factor to consider is the common mode voltage on the deflectors, some tubes like a little positive voltage there.Don
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Follow Ups
- Re: BDT preamp details - smoking-amp 10:00:14 07/09/04 (13)
- Degaussing...interesting...Degaussing for the tube enthousiasts ? - SomeJoe 16:17:46 07/09/04 (3)
- Re: Degaussing...interesting...Degaussing for the tube enthousiasts ? - smoking-amp 16:59:24 07/09/04 (2)
- Thanks! -- Can i use a hand-held demagnetizer? - SomeJoe 14:15:53 07/11/04 (0)
- Re: Degaussing...interesting...Degaussing for the tube enthousiasts ? - Eli Duttman 18:55:31 07/09/04 (0)
- Re: BDT preamp details - John Swenson 13:58:23 07/09/04 (8)
- Re: BDT preamp details - smoking-amp 16:46:10 07/09/04 (7)
- smoking-amp's scan - Bas Horneman 00:09:49 07/10/04 (6)
- Allen Wright is gonna love that circuit ... :-)) - Eli Duttman 05:34:02 07/10/04 (5)
- Yeah - except for the interstage and the NFB... (nt) - Allen Wright 11:07:32 07/10/04 (4)
- NFB, etc. - Eli Duttman 11:54:50 07/10/04 (3)
- I thought you would appreciate the TOTALLY balanced circuitry... - Allen Wright 03:56:00 07/11/04 (2)
- TOTALLY balanced circuitry - Triode Kingdom_ 12:41:38 07/12/04 (1)
- Yes... - Allen Wright 04:18:04 07/13/04 (0)
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