Bogen CHB-100 Tube Amplifier
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.
Bogen CHB-100 Tube Amplifier. 100 watts output. The amp works and sounds good, but the output tubes are not included. It uses four 7868 output tubes, but will run on two output tubes. The rest of the tubes are included. As you can see, the cosmetics are a little rough. With a little modification, these make great guitar amps.
About this model
The big one in the archive's Bogen collection: a CHB-100 rated at 100 watts, with four 7868 output tubes. The seller notes it will also run on two output tubes, which suggests the four are arranged as two parallel push-pull pairs. The 7868 is a nine-pin power pentode, smaller than a 6L6 or EL34, and four of them are a compact way to reach PA-level power.
This example came without output tubes and with rough cosmetics, and the seller pointed out that CHB-100s are often modified into guitar amplifiers. If you own one, find the schematic before changing anything; high-power PA amplifiers run high plate voltages.
| Maker | David Bogen Company, USA |
|---|---|
| Type | Public-address power amplifier |
| Rated output | 100 W (listing) |
| Output tubes | 4 × 7868 (listing) |
| Condition noted | Sold without output tubes (listing) |
Questions collectors ask
What output tubes does the Bogen CHB-100 use?
Four 7868 power pentodes, according to the archived listing, which adds that it will run on two.
Can I run a four-tube amplifier on two output tubes?
Some parallel push-pull designs allow it at reduced power, but the load presented to the tubes changes. Check the schematic and the speaker tap before doing it.
Sources: Wikipedia: Push–pull output.
