This post is probably of interest only to audiophiles. I have found the best vacuum tube amplifier ever made. Audio Power Labs, a new company introduced their only product, an 833 tube amplifier. The 833 tube is a massive transmitter tube. It’s use in audio is totally impractical, but it’s totally awesome. Unlike other megabucks amps based on transmitter triodes, the Audio Power Labs amplifier appears to be solidly engineered. I spoke with the engineer behind the product and he has decades of engineering experience.
The circuit design seems good. The input stage uses a differential amplifier. This is probably the best topology for an input stage, since it will have a high common mode rejection ratio, which is good for reducing hum. The output stage is push-pull, which is a relief after seeing so many ill-designed single ended amplifiers. Push pull operation reduces even order distortion. Transformer related distortions are reduced as well because the output transformers don’t have large DC currents running through them as in single ended operation.
The power output is incredible, producing 200 watts in class-A at only 1% THD. The amplifier sounds like nothing. Just as it should producing no coloration of its own. Despite using tubes, the modern features of this amplifier set it apart. Unlike many other designs which use a circuit lifted straight from the 1940s, this amplifier automates all biasing and calibration. Apparently, the amp can automatically bias unmatched tubes.
Aesthetically, this amplifier looks great. Everything is tucked away inside a massive aluminum block. The tubes look wonderful and are thankfully isolated from the user, especially the 833 tubes. The LCD screen adds a nice juxtaposition between classic and modern. The only downside to this amplifier is of course the expected power consumption. But then again, it wouldn’t be the most power hungry device in the house.
If you can afford it (final pricing hasn’t been announced), and want the best tube amplifier ever this is the one to get. It is worth mentioning that the amplifier is made in the USA.
Perhaps the best take on this amplifier is that it represents the artistic side of the engineer’s brain. Why should people only spend large sums of money on the works of artists, aren’t engineers artists in their own right?