Even if you aren’t a tube aficionado, you can’t help but be mesmerized by the blue glow inside a mercury vapor rectifier when it operates. It looks less like early 20th century tech and more like ...

Converting ac to dc has been accomplished by several different types of rectifiers through the years. Here are a few of the more common types of rectifiers used in the past 100 years. Mercury arc ...

A 4-pin plastic base with brass pins, two cylindrical electrodes mounted side-by-side below a metal cube. S-shaped envelope. Cold-cathode rectifier in original box with data sheet. Stamped on base: ...

The problem with tube based audio is that it has so often been hijacked by people for whom the bragging rights of having a tube amplifier outweigh the benefits, or the sheer fun of building the thing.