Park PMV800 Handwired

The PMV800 is the hand-wired Park Master Volume. When Marshall linked the Master Volume's channels together the JCM800 was born, and that circuit went on to carry rock through the seventies and eighties and to set the reference every high-gain amp after it was measured against. Park builds it here with hand-wired construction, high-spec components and transformers, five stages of filtering and a bypassable effects loop. Two inputs feed it: the high input cascades through four gain stages, the low input through three.

The additions are all reversible, which is the part worth knowing. PPIMV (Post Phase Inverter Master Volume) drives the power section hard at a manageable volume, and opening it fully removes it from the circuit. A Bright switch defeats the amp's stock bright cap when a particular guitar or set of pickups makes the top end harsh. A Mid Boost varies how thick the midrange sits. A three-way Gain switch offers both less and more gain than stock. Turn every one of them off and the PMV800 is back to the stock circuit, with the vintage feel and response intact.