what is the extra cutout on bottom of mark III head?

[jay]

my mark III simulclass,reverb,eq head has an extra cutout on the bottom of the amp. i have seen this on other mark III's may be on other amps too. of course the reverb is mounted on the bottom of the amp and there is extra material cut out for the reverb jacks to hook up. this extra cutout is on the other side and is bout 4 inches long by 1-1 1/2"wide. was this possibly for the fan to get air? mine does not have a fan.

 

[Russ]

The fan fits in there nicely if you do not have a reverb tank installed. I would assume that is why the cut out is shaped like that. My short Mark head case is like that. It is not a Mark IV head case so I am assuming it is Mark III because it is in like new tolex condition and was used when I got it.

 

[Boogiebabies]

If it's a short head, the fan only has 1/4 of an inch to draw air. The design is horrible and barely cools the power tubes.