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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: RE: DC Filaments for EL-34s? posted by Triode_Kingdom on January 2, 2010 at 16:50:16:
The cancellation is nearly true for class A. It is not true for class B. Since the amp in question is undoubtedly class AB, the hum should nearly cancel most of the time, since most of the time the amp runs in class A. However, in class B only one tube works at a time and the other tube is cut off, making cancellation of hum impossible. So on peaks there would be no cancellation of hum.
Even when run in class A, some of the intermodulation products of the hum signal and the music would be different on the two sides due to different amplitude levels of the music signal being mixed with the hum, so cancellation would be pretty good, but not complete.
I believe that running heaters on DC is always an improvement, though not always practical.
And the OP's expressed and implied goal is to maximize the sound of this amp (fifth rebuild), so no improvement is excess to him.
Another poster, I think about a month ago, stated that he was surprised at the improvement of moving the heater supply to a separate transformer. With the heater draw needed by the EL34, that's probably necessary anyway, making a DC supply all the more practical. And the heater supply could be on a separate chassis, if needed, with a small on-board filter to kill any small amount of noise picked up between the chassis (what is the plural of chassis?).
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Follow Ups
- RE: DC Filaments for EL-34s? - Lee of Omaha 01/3/1007:27:58 01/3/10 (1)
- There are some that feel AC gives you better . . . - John PA 11:20:53 01/3/10 (0)
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