Comments on Profile Post by Melvillian

Tried looking it up online and explanations usually just say that a transformers can be used, but not how it actually works.

There are quite a few youtube videos describing the basics of how a transformer works electrically (induction). In a sense, it's the differential (from your car) of the electrical circuit world...

Elevator pitch version. The + and - of the balanced side are connected to the two ends of one winding of the transformer and the other winding is wired to the two unbalanced connections (with a resistor in parallel I believe). This allows the two sides to float wrt each other, eliminating concerns about what ground means for each.

This one might help https://www.youtube.com/watch?v=GMePE7NZcxw

Thank you @crenca. I’m hoping to understand how the function of a transformer is utilized when converting balanced to single ended.

@MichaeLeroy so you’re Electrical isolating the ground from one side to the other? How about the differential circuit? Does the transformer do anything to the inverted signal?

The + and - ends of the balanced side are connected through the (primary) transformer winding. They drive (hopefully mostly AC) current through the coil, which induces current in the (secondary) transformer winding. The transformer transmits the balanced signal to the unbalanced side by EMF with no direct wiring, that's the float.

This picture might help: https://i.imgur.com/dRQfnm1.png

It's all about where the ground reference tap is, the transformer doesn't care but audiophiles do.

@Melvillian The voltage across the secondary windings is proportional to the voltage across the primary windings. The amplitude relationship between the two is dictated by the turns ratio (e.g., 1:1, 2:1).

Figure 16-5 of https://www.feynmanlectures.caltech.edu/II_16.html is a brilliant illustration of what a transformer does. The + and - ends of the balanced signal are the AC generator and the unbalanced side is the light bulb.

"...They drive (hopefully mostly AC) current..." Transformers don't pass, or to use laymans imagery "replicate", DC.

@Melvillian, it might help to think of a transformer as a "replicator" or "translator" (to use laymans terms). Instead of a directly connected mechanical circuit (like plumbing or a driveshaft) think of a transformer as two men sitting across a table, one side speaking one language and the other side "translating" it

I say "hopefully mostly AC" because the primary winding looks like a short to DC. If there is a DC (or very low frequency) signal on the balanced side, it will do little more than heat the transformer. Too much DC can ruin the transformer. I hope that most DACs have little or no DC signal on their balanced outputs.

Here is a TLDR version of the story :-) https://www.jensen-transformers.com/wp-content/uploads/2014/08/Audio-Transformers-Chapter.pdf

Basically the SE side is also balanced but you can safely ground one of the ends. If you ground the minus end of balanced DAC output, you could fry the DAC.

Grounding one of the ends makes (+1,-1) --> (+2,0)

https://www.youtube.com/watch?v=BthIwPmlKlc

@Cspirou that's what i wasn't understanding. It basically electrically isolates the two sides so that you can safely ground the inverted signal.

thanks everyone for your input. This is very helpful!

Yes, that is exactly what I tried to get across in my elevator pitch. The float provided by the transformer allows the connected system to respect the grounding schemes of both the balanced and unbalanced sides.

This has been fun discussion thanks very much @Melvillian for kicking it off.

isn't the short, simple answer that... balanced and unbalanced audio run at different voltages. Hence: transformer.

Balanced is higher voltage because you have two 2V signals. Add them up and you have 4V. You want to ground the inverted signal safely so you need a transformer to isolate from your source. That’s the simplest way I can explain it.