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Polarity Switch on a Single Ended Passive Preamp?

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Posted on April 15, 2017 at 05:15:13
tommylion
Audiophile

Posts: 4
Location: Vermont
Joined: August 3, 2016
 Is it possible to add a polarity switch to a passive single ended preamp that uses autoformers (as opposed to transformers)? Or a resistor ladder attenuator? If so, how would you do it?

 

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I wish you could, posted on April 15, 2017 at 07:31:59
rickmcinnis@dogwoodfabrics.com
Audiophile

Posts: 3040
Location: Atlanta
Joined: December 15, 2003
 AS told to me by Dave Slagle there is no way since the winding is shared.

I have a pair of transformers coming from him for this purpose. To be placed between two complimentary buffers. Wound 1:2 for approx. 6 db gain.

The idea is ZEN MOD's at DIYAudio.

I have tried the between two buffers idea for a low pass crossover using an LC filter and it works extremely well. But will have to hear how the gain aspect works with the transformer.

 

RE: I wish you could, posted on April 15, 2017 at 16:52:14
Mike B.
Audiophile

Posts: 26352
Location: OR
Joined: September 27, 1999
Contributor
  Since: September 1, 1999
 Check with K and K audio. He designed a output stage for me through a Lundahl transformer including a phase switch. Go to the asylum home page and look for his forum link


 

You missed my point, posted on April 17, 2017 at 10:12:08
rickmcinnis@dogwoodfabrics.com
Audiophile

Posts: 3040
Location: Atlanta
Joined: December 15, 2003
 I think.

You cannot change polarity with an autoformer.

Easy to do with a transformer.

Who makes the transformer has no bearing on it.

 

RE: You missed my point, posted on April 18, 2017 at 19:43:20
Mike B.
Audiophile

Posts: 26352
Location: OR
Joined: September 27, 1999
Contributor
  Since: September 1, 1999
 "Who makes the transformer has no bearing on it."

I would question this statement. Do all transformers in the signal path sound the same? The application I used also had gain and replaced the opamp.



 

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