16.5 " wide x 9.75 " deep x 2.75 " (at back. 2.25" front) chassis
Recommendations:
Chuck integrated chip-amp,
and build tube amp on chassis, mount it in separate Marshall-style box.
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12" underpowered "Fender Special" speaker, small magnet (prob.50w)
Bass Reflex Cabinet w. slot along bottom:
9" deep X 15 3/8" wide x 15 1/4" high (16 3/4" at back) interior box,
= 2140 cubic inches (1.24 ft³, .035 m³ )
with port/slot = 3/4" high x 16" wide, (12 Sq. In.)
and about 7" deep. (84 cubic in. in volume).
As it is, the cabinet has a horrible "honk/peak" with the low E string,
and another one about an octave higher. Very uneven bass response,
the four-knob EQ doesn't fix this,- not even in the ballpark.
Recommendations:
Put real 200 watt speaker in it,
seal port with plywood block,
add midrange speaker (in separate compartment) and crossover.
Reinforce cabinet walls with crossbraces,
and foam 3 sides inside to stop standing reflections.