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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: power transformer design questions or call it debate . posted by lovetube on April 25, 2012 at 20:55:47:
I'm a contrarian here (one of the reasons I rarely post), so take my remarks with suitable caution.
I think that magnetic headroom is very important. That means keeping the induction low - around 10kgauss for grain0oriented silicon steel cores, maybe 8 or 9kGauss for non-oriented materials. Even lower for small-signal power transformers. The reason relates to external radiated fields which induce hum and its harmonics, and also vibration which affects all the other components on the chassis. Keeping the core in it's more linear operating range reduces these problems.
Getting the induction that low requires more turns of wire, and/or a larger core, compared to the normal economic design. Both are expensive, so such transformers are rarely available except by custom design. The best you can do easily is to insist on 50Hz rated transformers operated at 60Hz. This will get you down to 13kgauss instead of the usual 16kgauss. An alternate is to use dual voltage transformers at half their design voltage (240v primary operated at 120v), giving 6.5 to 8kgauss - kind of overkill there.
Many here advocate low resistance, which is a consequence of using a transformer rated for much higher current that you are actually using. There are two benefits - lower internal temperature (giving longer life) and better regulation (more important for Class AB and B push-pull amps). This criterion also requires larger and more costly transformers.
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Follow Ups
- RE: power transformer design questions or call it debate . - Paul Joppa 22:05:13 04/25/12 (6)
- RE: power transformer design questions or call it debate . - danlaudionut 01:30:30 04/27/12 (5)
- RE: power transformer design questions or call it debate . - Paul Joppa 22:33:39 04/27/12 (3)
- RE: power transformer design questions or call it debate . - danlaudionut 09:34:34 04/29/12 (2)
- Overkill. - Paul Joppa 20:33:11 04/29/12 (1)
- RE: Overkill. - danlaudionut 22:41:01 05/01/12 (0)
- RE: power transformer design questions or call it debate . - Jim Womble 03:51:16 04/27/12 (0)
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