Hi John, Well I've owned both. The '82 version just sounds better. Ballsier.
It's a differant circuit board in the two and it could be the layout of the circuit board that contributes to the difference in tone. The voltages were also differant tho, with the '86 version having higher voltages on the pre amp tubes. And there are some minor parts differences too, though I'd have to dig out my notes to remember exactly what. One had a choke and one had a resistor, I remember that. The guy I sold my '86 side by side input 50 watt JCM-800 combo to loved it...but I didn't offer to let him compare it to my '82. I'm no fool! :laugh2:
Seriously, I spent alot of time tweaking my '86 (lowered the plate voltage on the preamp tubes to match my '82, etc.) to try and get it to sound as warm, full and ballsy as my '82, and though I was able to accomplish alot, it never did sound as nice, even with the same tubes and played through the same speakers. Didn't sound bad...just not as nice.
I'm not the only one who has noticed the diff between the two years when the two amps are played side by side.
Lew