Hello...I purchased my JCM 800 (serial#02726N) back in the Fall of 1981. I pulled the rear plate off the head for the first time so I could install new tubes for the first time. I expected to find four EL84's, but was totally surprised to find 2 KT66's, and 2 6L6GC's instead. Is this normal? The amp sounded totally different from other Marshalls I was exposed to, now I know why. Did Marshall do this often, or did they just run out of specific tubes and slap in whatever they had on hand. It's kinda hard to believe they did that as the KT66's require an entirely different transformer than the EL34's. Any comments or logical explainations?? Thanks.
Hello Randall,
Regarding your JCM 800, in the early 80`s our then American distrubutor wanted all valve amplifiers supplied to America to be shipped without power valves as they preffered to fit their own sourced power valves. Your amplifier would not have left our factory with two different types of power valves fitted.
Kind Regards
Marshall Support