A 2x12" combo had the option of sending the first channel into the second, probably inspired by Marshall users doing the same trick with a jumper cable. Most of these had Marshall layout and components, though some unusual amplifiers were made, such as a 75 watt keyboard amplifier with KT88 tubes. Starting in early 1965, Park produced a number of amplifiers including a 45 watt head. Marshall's contract did not disallow him from building amplifiers outside the company, and so Marshall launched the Park brand name, inspired by the maiden name of Jones's wife. The new contract had disenfranchised several of Marshall's former distributors, among them his old friend Johnny Jones. For export, they added 55% onto my price, which pretty much priced us out of the world market for a long time." Park amplification In retrospect, Marshall admitted the Rose-Morris deal was "the biggest mistake I ever made. Marshall entered into a 15-year distribution deal with British company Rose-Morris during 1965, which had given him the capital to expand his manufacturing operations, though it would prove to be costly. Note: the actual wattage of the JTM-45 is 30 watts. This new amplifier, tentatively called the "Mark II", was eventually named the " JTM 45," after Jim and his son Terry Marshall and the max. These circuit changes gave the amp more gain so that it broke into overdrive sooner on the volume control than the Bassman, and boosted the treble frequencies. Other crucial differences were the use of higher-gain ECC83 valves throughout the preamp, and the introduction of a capacitor/resistor filter after the volume control. For their Bassman, Fender used four Jensen speakers in the same cabinet as the amplifier, but Marshall chose to separate the amplifier from the speakers, and placed four 12-inch Celestion speakers in a separate closed-back cabinet instead of the four 10-inch Jensens in an open-back combo. Speakers were then rarely able to handle more than 15 watts, which meant that an amplifier approaching 50 watts had to use four speakers. The first few production units almost copied the Bassman circuit, with American military surplus 5881 power valves, a relative of the 6L6. The sixth prototype produced, in Jim's words, the "Marshall Sound". They made several prototypes using the Fender Bassman amp as a model. He enlisted the help of his shop repairman Ken Bran and an EMI technician named Dudley Craven, and between them they decided they most liked the sound of the 4x10" Fender Bassman. Jim Marshall thought he could produce a cheaper alternative to American-made guitar amplifiers, but he had limited experience as an electrical engineer.
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