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Dual-Coil Choke for Tube Preamp
Dual-Coil Choke for Tube Preamp
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Old 15th July 2005, 10:57 AM   #11
CLS is offline CLS  Taiwan
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Red face I figure it out now

Inductor works when flux changes.
Cancelling out the flux, then there's no reactance.

I'll lookin for another solution.
Thanks for messing with my confusion.
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Old 15th July 2005, 11:28 AM   #12
Eva is offline Eva  Spain
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But you have two channels and two dual inductors, isn't that enough?

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Old 15th July 2005, 04:35 PM   #13
Sch3mat1c is offline Sch3mat1c  United States
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Originally posted by CLS
I just thought it's almost the same as a pp output stage.
It would be if the tubes were driven inverted, as they are in a PP amp. Rectifier circuits can't even show an inverted signal (it always looks like a series of humps), let alone shift the phase to make it look right. THAT is why your choke would've been useless.

Instead you have to make them bounce in sync. Dotted end of the winding to rectifier, other to caps.

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Old 18th July 2005, 02:22 PM   #14
CLS is offline CLS  Taiwan
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Understood & thanks a lot.

I just finished the project (well, sort of).
Eventually I used them conventionally in series in the LCRC filtering.

So, that's 15H-> 220uF (with 68k bleeder), followed by individual 2k-> 1000uF for each CK5842 (with 47k bleeder).

The main transformer gives 210VAC, instead of 230 in the specs. (I'm a little confused because the output of all the rest taps are very accurate. This Lundahl unit is also very well built.... )

Via one & a half hybrid bridge by 2* 6X5GT & 2* 1N4007, I got 189V on the LC with 0.7V ripple (measured by DMM).

Then the final RC brings the voltage down to 155V with 0.52V ripple. Well, not quite up to the target, but acceptable.

I'll share the rest of the project in the Tube forum.
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