Bogen Challenger MX6 Microphone Mixer
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.
Vintage Challenger MX6 Pre-Amp. All of the tubes light up and are included……
2) 12AX7
1) 12AT7
There are 5 control knobs on the front for On/Off, Mic-1, Mic-2, Mic-3 and Mic-4. The back panel has four 1/4″ MIC Inputs and two 1/4″ Phono Inputs, plus a shielded wire with an RCA plug for the speaker output. We tested all inputs on this amp with a microphone using an 4 Ohm speaker for output. All the tubes light up and all capacitors stayed nice and cool during our testing. All of the knobs work and turn freely as they should but the output of this one is very faint. So it will need some work or possibly new tubes to bring it back up to its full potential.
It looks like all the components underneath are still original and the chassis and cage are in good cosmetic condition as well (please see photos). So this one is a great candidate for a rebuild (I’ve heard one of these in good working order and they are VERY nice sounding amplifiers! It measures approximately 8″ x 5 3/8″ x 5″ and weighs about 8 lbs. unpacked.
About this model
The MX6 is not a power amplifier at all. It is a Challenger microphone mixer: five knobs on the front (power and four microphone levels), four quarter-inch microphone inputs and two phono inputs on the back, and three small tubes inside, two 12AX7s and a 12AT7. A unit like this fed a separate Bogen power amplifier in a school or a small auditorium.
This example lit up but gave only a faint output, so the seller sold it as a rebuild candidate with its original components and cage intact. Dimensions in the listing: about 8 × 5⅜ × 5 inches, roughly 8 pounds.
| Maker | David Bogen Company, USA |
|---|---|
| Series | Challenger |
| Type | Four-channel microphone mixer / preamplifier |
| Tubes | 2 × 12AX7, 1 × 12AT7 (listing) |
| Inputs | 4 × ¼-inch microphone, 2 × ¼-inch phono (listing) |
| Size and weight | About 8 × 5⅜ × 5 in, 8 lb (listing) |
Questions collectors ask
Is the Bogen MX6 an amplifier or a mixer?
A mixer-preamplifier. It combines four microphone inputs and passes the signal on to a power amplifier.
Why does an MX6 use both 12AX7 and 12AT7 tubes?
They are related dual triodes with the same pinout but different gain, about 100 for the 12AX7 and about 60 for the 12AT7. Designers mixed them to get the right gain and drive at each stage.
Sources: Wikipedia: 12AX7.
