Dating vox ac50
Read more Max Guitar is crazy about the older Voxes…and especially the ones with a little extra historical value. Their success helped to make Vox the dominant brand of guitar amplifiers in the world at the time.
This one is from either late 1965 or 1966 (defined by the #09 backplate) and is very collectible and great sounding amp. Vox was so proud of the brilliant frequency response produced by their signature “Top Boost” tone circuitry that they gleefully proclaimed their amplifiers could produce “glass shattering treble” in a 1964 product catalog. The bright, poppish guitar sounds from the early “British Invasion” were being replaced by a darker, overdriven tone.
The version below is redrawn (sized to print at A4).
The preamp valve cathode bias caps, marked on the schematic as 25uf, were in production 32uf. Some thin-edge amps were apparently designated for bass - serial numbers 1005B and 1035B, for instance, below.
While Vox did not seem at first to respond to these changing tastes in guitar tone, upstart amp manufacturer Jim Marshall did.