Bogen Challenger CH20 Mono Tube Amplifiers
Archived listing from the original vintage-amplifier.com. Prices, seller details and purchase links have been removed; this page is a reference record, and nothing here is for sale. About this archive.
A pair of Bogen CHA-20 tube power amplifiers. Bought as a project, which my father never realized. The units power ON, the tubes glow up, but we didn’t test them further. Sitting for years without use. My father has much more stuff to do and never had time to take a look closely. They are in nice condition, no rust. Only very little imperfections on them. Considering the age, they are in beautiful shape. Each amp has one 6AX5GT rectifier, two 12AX7 and two 6V6GT tubes. Comes with original cages, the models are same, but the cages are slightly different lookwise.
About this model
The post title says CH20, the seller's text says CHA-20, and Bogen used both prefixes across the Challenger range, so the two names are best read as the same family. This pair had sat unused for years; they powered on and the tubes lit, and that was as far as the testing went.
The listing does give the full tube line-up per amplifier: one 6AX5GT rectifier, two 12AX7 preamp tubes and two 6V6GT output tubes. That is a classic small push-pull layout. A pair of 6V6s gives roughly 14 watts by the tube's published data, which fits a 20-watt nameplate for a public-address amplifier rated at peak rather than continuous power.
| Maker | David Bogen Company, USA |
|---|---|
| Series | Challenger (public address) |
| Type | Mono amplifier, sold as a pair |
| Rectifier | 6AX5GT |
| Preamp tubes | 2 × 12AX7 |
| Output tubes | 2 × 6V6GT, push-pull |
Questions collectors ask
What output tubes does the Bogen CH20 use?
According to the archived listing, each amplifier has two 6V6GT output tubes, two 12AX7s and a 6AX5GT rectifier.
What does a pair of 6V6 tubes deliver?
Manufacturer data cited on Wikipedia gives about 5 watts for a single 6V6 and about 14 watts for a push-pull pair.
Sources: Wikipedia: 6V6; Wikipedia: 12AX7.
