North Reading Engineering Autotransformer ATXR

[nre]

ATXR auto-transformer tap table is shown.  P0, P1 and P2 are inputs.  RMS voltages shown are with 10VRMS, 1kHz at the selected input tap (P0, P1 or P2).



The auto-transformer front and back shown below.

[deafbykhorns]

That's excellent! .7db taps will give much better control over midrange selection. This is better than the proprietary xfrmr UTC won't sell to the public (3619-ET)
Has this been tested for lower energy devices(tweeter)?

[nre]

That's excellent! .7db taps will give much better control over midrange selection. This is better than the proprietary xfrmr UTC won't sell to the public (3619-ET)
Has this been tested for lower energy devices(tweeter)?

Yes, sir, will work fine with a tweeter.

[nre]

[deafbykhorns]

I like the visual of the autoformer diagram. Its what I visualized, I see how you get the finer taps and it will work with those 115dbw horns!

[deafbykhorns]

How does this look for layout?
https://photos.app.goo.gl/KqQqoJtSEMrKmRKa8

[nre]

I would prefer to see the autoformer GND tap have a single lead going to a dedicated location on the network board where the amplifier negative terminal and the shunt resistor negative lead attach directly.  The shunt resistor could then be mounted off the autoformer.     

I sent quick disconnects for the autoformer which will allow experimenting with the attenuation levels.

Also, you can just and drop photos into the post, you don't need third parties, fwiw.

[mboxler]

Hey John

I'm probably reading your chart wrong, so I'm attaching two diagrams for clarification.  The first shows the amp connected to P1 and GND, and the load to T3 and GND.  I believe you are saying that if the voltage across P1 - GND is 10, then the voltage across the load (T3 - GND) would be 7.6.  You are then saying that if the amp were connected to P0 - GND, then the voltage across the load (T3 - GND) would be 6.9. 

Shouldn't the voltage across the load be increasing instead of decreasing? 

Again, I may be reading you chart wrong.

Mike

 

[nre_admin]

Mike-

The sketch is incorrectly drawn.  It should be P0, P1, P2 top to bottom.  The table is correct however.

Apologies and good catch.

jw