Just Bought a 400+ and decided a ABS plastic case was the way to go for weight reasons, so I bought a 6u and drilled some holes in the handle recess for the fan to get some air, put the amp in the rack, turned on and played for maybe a hour no problem, the amp then blew the fuse replaced it and blew another, the 400+ felt quite hot too, does anyone have a ABS case with this amp and what did you do? Would taking the entire handle recess away help? Thanks
You could just try adding a secondary (clip-on) fan at the rear to help. My 400+ blew fuses when one power tube wasn't fully inserted into its socket. (you might check yours; you may have knocked one loose when transferring over to this rack)
I have used a 4 space Gator rack case for a while now with my 400+ with no problems at all. I have drilled holes by the handle mounts as you have, but IFIRC when I chose the Gator case it was because the handle mounts were in the right place for the fan and the sides were "looser" fitting. Because of the position of the Mesa fan I think it is around the sides that you most need space.I run mine loud and hard much of the time, usually with the fan on slow unless it is a hot outdoor gig - never a problem.
I doubt very much if the fuses blowing had anything to do whatsoever with cooling. Tube amps just plain run hot compared to solid state stuff, and in all likelihood, the temp was fine . . . and the fuses blowing was due to something else altogether . . . - Tim
I'd check this first, blowing a fuse means there's something wrong with the electrical signal and it's blowing the fuse instead of shorting out your amp. Temperature wouldn't have anything to do with the fuse at all. Fuses are there to avoid melting your amp due to short circuits, not just getting hot. Basically the fuse melts because excessive current is hitting it, and the fuse melts keeping the excessive current from going into the rest of the circuit. Anyway end with the electrical engineering lesson, basically the fuse is having problems because there's something wrong with the circuit... which would be something as simple as a tube not being all the way in.
I agree with the other posters here: I haven't heard of any over heating problems particular to that amp. The most common cause of "failure" in a tube amp is the tubes. And, if one of your tubes goes down, it can certainly blow fuses. I would not play the amp further until you replace the tube/tubes. If you don't you can start taking out resistors et al.
Thanks for the advice I'll take it back to the shop for a checkup hopefully theres nothing too bad..S
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