|Power Bias||cathode biased|
|Preamp||7025, (1/2) 7025|
|Reverb||(1/2) 12AU7, (1/2) 7025|
|Vibrato||(1/2) 7025 (oscillator), 12AU7|
|Phase Inverter||(1/2) 7025 for gain, (1/2) 12AU7 for paraphase.|
|Speaker||12" 8ohm Oxford 12K5R-7|
|Output||27 watts peak|
While it resembles the bigger M10 in a few ways (12" speaker, vibrato, and reverb), the M8 uses a smaller, more economical 8K:1 transformer, a smaller weight speaker, and the two varistor version of the F.M. Vibrato. It is also a cathode biased circuit instead of the fixed biased circuits used on M10's.
The M8 reverb is different than the M10, M13, or M15 reverb. The schematics below show that one circuit drives the reverb tank with the cathode, the other with the plate.
The photo schematic was found at this cool amp site https://irationaudio.com/2015/10/31/magnatone-m8/.