The Vox UL730 power section schematic – OS/114
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Above, OS/114 for the Vox UL430 and Vox UL730 power section, dated 28th February 1966. Note that a small batch of pre-production amps – made at much the same time as the Beatles’ small-box 7120s – were built differently. At least one of these early 730s survives (currently in the UK).
OS/114 indicates that the negative feedback line should only be for UL430 bass amps (FOR BASS MODEL ONLY). As mentioned in the post below, UL760s had no feedback circuit to begin with, but at some point mid production one was subsequently added.