What is the manufacturing model name of the Plexi 50W Normal in the axe3?

E

Emerald Green

Inspired
Been lost for hours with this amp and I´m just curious of what model/circuit it is.
I could not find any model name on wiki but I found out elsewhere that during 1972 there was model 1987 and the 1972
superlead 50W (a babybrother to the 100W SPL)
Don´t know if these two amps are the same and has the same circuit.
Also read that 1972 was the last year Marshall did point to point hand wired amps before the switch to pcb in 1973.
According to Solodallas, Marshall also replaced the EL34 tubes with 6550 power tubes in the amps shipped to the US 1972 because the EL34 was too fragile and were breaking too much often within warranty time. The one we have modeled is equipped with EL34 mull tubes so it could be an early shipment. I know we have a 50 W 6550 as well but I´m not sure if that one has the same circuit as the 50 W normal with just the 6550 tubes?
I guess Marshall didn´t produced a lot of different models during 1972...
so if anyone knows the model or circuit for this one other than just "plexi" it would be great.
I think this one (the plexi 50w normal) also has a solid state rectifier......but I´m not sure.
 
Emerald Green said:
Been lost for hours with this amp and I´m just curious of what model/circuit it is.
I could not find any model name on wiki but I found out elsewhere that during 1972 there was model 1987 and the 1972
superlead 50W (a babybrother to the 100W SPL)
Don´t know if these two amps are the same and has the same circuit.
Click to expand...
Same amp, not sure if the US spec model was introduced by then, but there were more differences than just the change from EL34 to 6550 when they made that change. I think there were also some different plate resistors on the preamp tubes, the "slope" resistor in the tone stack was changed, and if I remember right there were also some changes in the bias circuit for the power amp input. My wild guess is that we have a UK spec '72 1987 "metal face" 50W model in the Axe FX. It sounds a lot like my UK spec '78 1987 50W head.

Emerald Green said:
Also read that 1972 was the last year Marshall did point to point hand wired amps before the switch to pcb in 1973.
According to Solodallas, Marshall also replaced the EL34 tubes with 6550 power tubes in the amps shipped to the US 1972 because the EL34 was too fragile and were breaking too much often within warranty time. The one we have modeled is equipped with EL34 mull tubes so it could be an early shipment. I know we have a 50 W 6550 as well but I´m not sure if that one has the same circuit as the 50 W normal with just the 6550 tubes?
I guess Marshall didn´t produced a lot of different models during 1972...
so if anyone knows the model or circuit for this one other than just "plexi" it would be great.
I think this one (the plexi 50w normal) also has a solid state rectifier......but I´m not sure.
Click to expand...
Yes, all the 50W models I know of have silicon rectifiers. Not sure any of the older "plexi" models are genuinely plexi. The 50W and 100W heads changed from plexi to metal control panels in 1969. From 1972 the 50W amps have a reputation for sounding more aggressive, but I do wonder if people are comparing US spec with UK spec, and therefore apples with oranges. So many tiny variations on a theme, and I don't feel any of them sound less than great.

Liam
 
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