Cerise
Despite our reservations about the closed cabinet and heat issues, as far as I know, no problems has been reported on that owners' club pages. And as people have indicated on the internet, a better design would push the amp into AC15 price range.
As for opening the back to manage heat, a lot of small amplifiers (and many larger ones) has the tubes hanging upside down behind, and close to, the speaker magnet. Most of these has a C-channel chassis, so the heat conducts upwards to the top, via a reasonably closed-box, unventilated area where the electronics sit, to the control plate. In the AC10C1 that path is a long one. In the rest, it is a few centimeters at most. As an example, the Laney Cub Ten is open back, with no vents on top. It gets warm to the touch, but not hot. At least the Vox has a vent at the top, sited so that the airflow has to go past the electronics. The heat will conduct up via the chassis plate, yes, but it will run much cooler than the closed box. I would like to invert the power valves, and have them sit on top of the bracket, just to get the heat off the sockets and PCB, and to get the valves away from the magnet.
These amplifiers have been in use for several years, I have not read about any blow-ups or fires. Would I have bought a "better" one at a substantially higher price? No. I would then have invested in an AC15 Handwired instead, that would have been the price bracket. Would I like to have a handwired AC10C1, all valves and no MOSFET? Very much so, but it would really be an AC15 with a off-spec (10kOhm) output transformer and 10 inch speaker, in a not much smaller box. The compromises to get this thing so small and handy is not optimal, but it seems to work sort of OK.
