Based on the Marshall® JTM-45
(no master) –> default setting 10
One of the earlier amps that, as mentioned above, found its inspiration in the tweed Fender®Bassman®, but nevertheless managed to sound like something quite different as it took on several constructional twists and design elements that marked the beginning transition from a mellower Fender like tone to the distinctive, bright “crunchy” sound of all Marshall® amps to follow. Hefty, high-quality British transformers and KT66 output tubes (a 6L6 equivalent, but with more power and punch) gave the JTM-45 a huge soundstage and a smoother overdrive tone than the later EL34-based Marshalls that more players are familiar with today. Cranked through a closed-back 4×12” cab with Celestion® G12M “Greenback” speakers, this rig evokes the archetypal Brit-rock and blues-rock guitar tone. Interesting side note: this is the exact same amplifier as the Marshall® “Bluesbreaker” that Eric Clapton made famous, but in head form, rather than housed in a 2×12” combo. This is your starting if you’re looking for that ‘beano’ tone.
Brit J-45 NRM: The Normal channel is the mellower of the two, with less (as you’d expect) brightness and gain than the Bright channel.
Brit J-45 BRT: The Bright channel utilizes the second half of the first preamp tube (the Normal channel uses the first half only) for a different voicing. High frequencies are increased due to an inter-stage high shelving filter
It’s a bass-heavy amp –> Decreasing Bass could be a good tip. Great for clean tones as well as rock tones