Audio QOTD: Balanced Lines

[Chris15]

I still maintain the transformer in the schematic would prevent phantom power on pins two and three from reaching the cartridge (please correct me if I am wrong, but as I understand it the positive side of phantom power is applied to pins two and three, and the negative side is applied to pin one).

Yes, the transformer would block the phantom, but it actually doesn't have to. Because phantom is applied equally to hot and cold (in most cases at +48v) via matched resistors, there is no DC difference between the two lines and so there is nothing that the transformer has to block if that makes any sense. If the you had one end of the transformer primary tied to pin 1 a la ground, then sure the transformer would block the DC transfer, but I won't go too far into it, but let's just say you'd have some other issues at that point.

 

[philhaney]

Because phantom is applied equally to hot and cold (in most cases at +48v) via matched resistors, there is no DC difference between the two lines and so there is nothing that the transformer has to block if that makes any sense.

Yes it does.

Thank you very much.

 

[mbenonis]

Dillon, Great question. I know I would love to see more Audio QotD's, if you're prepared to post them.

BTW, the link to the balanced line white paper is great. I know I learned a thing or two.