questions on input transformers

1. How do I wire it for balanced/unbalanced input to balanced output?

I saw this guide from Lundahl's site (https://www.lundahltransformers.com/using-the-ll1545e/) on how to wire unbalanced/balanced input to balanced output.

Can I use the same guide for other manufacturer's input transformer ( example: Hammond 560G) that has the same "pinout" (unsure of the correct term to use here) as the LL1545e? Only asking since Lundahl's are not easy to find in my location.

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2. I've seen 1:1 and 1:4 transformer? Are pros/cons to the different ratio?

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3: How do I know an input transformer is suitable for unbalanced/balanced input to balanced output application?

I was just looking at the lundahl site, there so many input transformer (example: LL1544a vs LL1545a vs LL1690) that seems to do similar things.

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Thanks a lot
 
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1) Yes, if they have either two primary windings or a centre-tapped primary winding.

2) 1:4 increases the signal voltage by four and the impedance by 16. That can be handy when you have a very low level signal source with a low impedance and want to connect it to an amplifier with a very low equivalent input noise current, but not so low equivalent input noise voltage. Typical example: microphone preamplifier in valve technology.
 
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@MarcelvdG another question please.

does the static resistance of the winding matter? Thanks again!

as an example (taken from the screenshot of the respective datasheets):

LL1545E.png
Microsoft-Word-1540-doc.png
 
1. How do I wire it for balanced/unbalanced input to balanced output?

I saw this guide from Lundahl's site (https://www.lundahltransformers.com/using-the-ll1545e/) on how to wire unbalanced/balanced input to balanced output.

Can I use the same guide for other manufacturer's input transformer ( example: Hammond 560G) that has the same "pinout" (unsure of the correct term to use here) as the LL1545e? Only asking since Lundahl's are not easy to find in my location.

-----------------
2. I've seen 1:1 and 1:4 transformer? Are pros/cons to the different ratio?

-----------------
3: How do I know an input transformer is suitable for unbalanced/balanced input to balanced output application?

I was just looking at the lundahl site, there so many input transformer (example: LL1544a vs LL1545a vs LL1690) that seems to do similar things.

-----------------
Thanks a lot
So what is the application?
Usually, unbalanced inputs are not wired with a transformer. But it can be done. However, not with the transformers you have looked at this far.
Output transformers can be used for input transformers. Some that are gapped would have a little bit of loss, but they all will work.

This transformer might be what you looking for, as I use it for mid/high Z interfacing unbalanced and balanced equipment in stadium and theater installs. The transformers you are looking at is the lower Z transformers used in vintage line level conventions that are obsolete.

https://www.jensen-transformers.com/product/din-2li/
 

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