RE: Choke VS Transformer

Posted by Triode_Kingdom (A) on January 31, 2016 at 09:49:33

In Reply to: RE: Choke VS Transformer posted by gavinhaley on January 31, 2016 at 09:12:53:

OK, I see where you're coming from. Here's my attempt to describe it...

The original circuit uses a center-tapped choke. The two halves of the winding are closely coupled, perhaps bifilar-wound to assure symmetry. Because of the coupling, any current flowing through one half of the winding creates an equal but opposite current in the other half.

The reason the choke must be specifically designed for this use is that one winding is operating with a virtual open circuit (the grid of the lower 2A3). Even if voltage balance weren't an issue, most transformer windings are designed to operate with a specific operating impedance. Failure to maintain the proper load causes frequency response anomalies, such as high- or low-end rolloff. Operating a standard transformer at too high an impedance can also create undesired resonances that degrade frequency response within the passband.

Regarding the voltage balance I mentioned above, even in this case it will gradually degrade as frequency rises. Inter-winding capacitance will affect the open-circuited winding well before the winding that's attached to the lower operating Z of the driver tube. However, the same design techniques that allow the transformer to exhibit good high-end response into an open circuit should move this characteristic well out of the range of audible frequencies.

Hope this is clear. I'll be glad to go into more detail if needed.

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Follow Ups Full Thread

Topic - Question about transformer phase splitter as used in "Seth Amp". - gavinhaley 07:30:57 01/31/16 (17)

RE: Question about transformer phase splitter as used in "Seth Amp". - Tre' 07:52:45 01/31/16 (16)

RE: Question about transformer phase splitter as used in "Seth Amp". - gavinhaley 08:01:16 01/31/16 (15)

RE: Question about transformer phase splitter as used in "Seth Amp". - GEO 13:10:51 01/31/16 (1)

RE: Question about transformer phase splitter as used in "Seth Amp". - bean 20:42:41 01/31/16 (0)

RE: Question about transformer phase splitter as used in "Seth Amp". - Tre' 08:58:05 01/31/16 (0)

RE: Question about transformer phase splitter as used in "Seth Amp". - Palustris 08:44:15 01/31/16 (11)

RE: Question about transformer phase splitter as used in "Seth Amp". - SteveBrown 11:52:55 01/31/16 (0)

Choke VS Transformer - Triode_Kingdom 09:00:49 01/31/16 (9)

RE: Choke VS Transformer - gavinhaley 09:12:53 01/31/16 (8)

RE: Choke VS Transformer - Triode_Kingdom 09:49:33 01/31/16 (6)

RE: Choke VS Transformer - dave slagle 19:39:59 01/31/16 (3)

RE: Choke VS Transformer - Triode_Kingdom 07:14:25 02/01/16 (2)

RE: Choke VS Transformer - dave slagle 09:43:12 02/01/16 (1)

RE: Choke VS Transformer - Triode_Kingdom 11:13:02 02/01/16 (0)

RE: Choke VS Transformer - gavinhaley 10:26:13 01/31/16 (1)

RE: Choke VS Transformer - Triode_Kingdom 11:18:09 01/31/16 (0)

RE: Choke VS Transformer - Tre' 09:34:21 01/31/16 (0)

Follow Ups

RE: Choke VS Transformer - Triode_Kingdom 09:49:33 01/31/16 (6)

RE: Choke VS Transformer - dave slagle 19:39:59 01/31/16 (3)

RE: Choke VS Transformer - Triode_Kingdom 07:14:25 02/01/16 (2)

RE: Choke VS Transformer - dave slagle 09:43:12 02/01/16 (1)

RE: Choke VS Transformer - Triode_Kingdom 11:13:02 02/01/16 (0)

RE: Choke VS Transformer - gavinhaley 10:26:13 01/31/16 (1)

RE: Choke VS Transformer - Triode_Kingdom 11:18:09 01/31/16 (0)

RE: Choke VS Transformer

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