Got to say Voodoo I strongly disagree with your comment on swapping out valves, though it's great to come across another sceptic. Coming from a long electronic engineering background, I'm the arch sceptic of mojo! I promise you, you could not be more against the idea of differences in sound caused by capacitor types, transistor types, diode types, than I am! It's all hogwash and generates money for people who don't generally deserve it. Double blind testing proves that no one, not even the golden auricularly gifted brigade, can hear differences when tests are done rigourously. And I used to feel the same way about valves. That was until I got my hands on a TM36.
Generally I loved it but found it could be strident, fatiguing and lacking bottom end. So I sorted out speakers and bottom end appeared, but it was still a tad fizzy and harsh at the top. So I bit the bullet and tried a couple of Electro Harmonix ECC83s I had lying around, never expecting things to alter. And what do you know, things genuinely improved. Now with the easy valve changing capabilities of the H&Ks it is simple to swap and retry without too much delay between. I swapped and tried a good number of times before I was convinced that I was not tricking myself. I was forced to admit that it was a real phenomenon. So I invested in a set of JJ EL84s and it really made more of a difference.
Now I have a GM36 as well, I have gone a stage further and introduced a JJ 12AX7 in V1 and a Mullard NOS 12AT7WA CV4024 into my V3 position as the phase inverter. The gain has gone down a tad, the last vestige of roughness has been removed and I can leave it alone and just play. Sadly I had to admit that valves are not only electronic components, they are reliant on mechanical construction and materials for their electrical action. If there is one component which will show differences, as you said not night and day but discernible, it is them.
And I still preach (endlessly, apologies to all
) against the crap talked about capacitor choice in guitar tone controls, mojo diodes in distortion pedals, and magic transistors in amps and pedals in general. None of it makes a Scooby Doo of difference in a guitar application. The only difference is in your wallet afterwards.
And as to the heat issue.... Have you seen my thread on a forced cooling plinth with computer fans in the TM36 forum?
That diy unit also fits the GM36 of course. I have it better finished now and it really does the job splendidly, although I do believe it's actually not quite the problem people may think. The extreme heat comes from the valves, everything else, even the power soak, is in the range that electronics copes with every day. The valve generated heat travels upwards in the upper chamber and is soaked away very effectively by the top and back metal. UYou don't get that with an old school wooden case head. The lower compartment is actually fairly well insulated from it.