Mysterious Marshall JTM45 amp

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Re: Mysterious Marshall JTM45 amp

Postby Kalle_in_Sweden on Fri Sep 25, 2015 3:39 pm

Hi LD50
That was my goal with this test, just to find out if it´s a approx 8 kohm trafo ( for KT66 tubes) and not a trafo for EL34.
I measured once again with 12VAC / 880Hz into the 8 ohm tap and measured 370VAC between node-anode taps
=> voltage "gain" = 30.8 >> 30 x30 = impedance "gain" = 949 >> 949 x 8 ohm = 7600 ohm
/kalle
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Re: Mysterious Marshall JTM45 amp

Postby Kalle_in_Sweden on Fri Sep 25, 2015 6:23 pm

I have now decoded the schematic av the complete active Baxandall stack
Image
/Kalle
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Re: Mysterious Marshall JTM45 amp

Postby API on Mon Oct 12, 2015 9:16 pm

I checked the pictures on the Swedish site and i saw that it has a plexi JMP frontpanel but with a white back.
Do you know if the frontpanel was changed at some point?
1966 JTM45/100, 1967 "1959" Super Lead, 1967 "1961" JMP 4x10" Mk I Bluesbreaker, 1967 "1962" JMP 2x12" Mk I Bluesbreaker, 1967 "1973" Master Reverb 18w combo, 1963 AC30, 1964 AC15 Twin, 1963 Watkins Dominator, 1965 Princetone Reverb, 1957 Gibson GA-40 Les Paul, 1962 Gibson GA-40 LP, 1962 Epiphone Pathfinder
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