|Vibrato||12DW7 (oscillator), 12AU7, four varistors|
|Output||38 watts peak|
The M9 is a 2 channel amp with F.M.Vibrato driving a 15" speaker. Each channel has "loudness", "tone", and "contour" controls. A stereo input jack allows a single instrument cable to feed signal to both channels (jack is a stereo connector, not a mono jack). The four varistor vibrato is only on "Channel One". The M9 used a cathode-biased pair of 7189A power tubes. This distinction made the M9 (and M8) unique among many of its stable-mates that used a fixed-biased output section with 7189A's
While both the M8 and M9 were cathode-biased, only the M9 used the larger 10K:16ohm ultra-linear output transformer.
M9's were introduced in the second half of 1963 as part of the new line of Custom Series amplifiers. By mid 1965, the entire line was revamped and several models were discontinued. The M10 survived as the 1x12" M10A, and the somewhat similar M8 and M9 were among models axed.
The M9 pictured at right has an acrylic badge that was used a few Custom Series amps. See Custom Series Dating for more about this nuance.