So I hear the old JCM800's were kinda hit or miss

[mort]

I don't personally have alot of experience with them but that's what I hear, that some sounded great, some not so much. Just thought I'd pose the question here as to why. Anyone have any insight into this?

[robrob]

There was a crap ton of parts substitutions for many of the classic Marshall amps. Caps especially varied in value, even the negative feedback tap could be from the 4, 8 or 16 ohm taps giving a great deal of NFB voltage difference. Some of the changes were intentional tweaks, some were made because that was the part they had on hand that day. That's my best guess as to why they seem to vary in tone.

https://robrobinette.com/How_the_Mar...M800_Works.htm

[big_teee]

I only have experience with clones and remakes.
They vary greatly, depending on schematics and parts, & which tubes you use.
My least favorite was the JCM800 with the .0022uf 1b plate coupling cap.
I always use a .022uf instead.
T