If it plugs into the wall it has a power transformer.
Power transformers have an impact on sound quality—one that is not small nor trivial. In fact, power transformers play a significant role in our sound systems, yet not that many designers pay them close enough attention.
I figured we'd delve into the nature of these beasts over the next few days. A lark, really, but perhaps one that will help a few gain understanding of what's inside their equipment and why it's there. Let's start with that.
Power transformers have two key functions: isolation and proper voltage. Let's talk isolation first.
We know better than to stick our curious fingers into the AC wall socket. While not usually lethal in the United States, that isn't true in most of the rest of the world where voltages are doubled. You definitely don't want 230 volts coursing through your heart for too long. Isolating the equipment you interface with is a good thing, and transformers do it well.
Near magical devices, transformers work through invisible means. There is no physical connection between the wall socket and your equipment. Instead, power is transferred through a magnetic field, helping keep us disconnected from the house wires—and safe.
Tomorrow let's look at the second function transformers provide.