Metal Grill 4x12 Halfback Panel Dimensions?

[petruccirocks02]

I picked up a metal grill halfback 4x12 in awesome shape that is loaded with four EVM 12L’s.

The bottom panel is already closed. If I wanted to get a panel made to close the top would the dimensions be the same as the bottom panel? And is there a way to attach the panel without screwing it in, so it could go back to stock form easily?

I read on another forum that if the top panel wasn’t fully sealed that it could damage the speakers. Does anyone know if that’s true at all? Thanks all!

 

[fretout]

1. The dimensions of the top panel can simply be taken directly from the open area of your cab.

2. Mesa screws their back panels through that lip you can see in your pics. If you choose to do this, expect to have a bunch of new holes that will be visible when the panel is off.

3. I only have one 4YB that came with the top panel closed, but I believe it was a home project from the previous owner. However, my cab and speakers are not damaged by the back being fully closed. I’m not sure where that concern comes from, but think about the bottom speakers. They aren’t damaged by the back being closed, so the top shouldn’t be damaged either.

One consideration I would recommend based on my experience is to be careful how close the top panel is to the bottom panel. The top panel on my cab was installed directly on the bottom panel…and this caused friction between the two panels. It sounds like you care about the wear on your cab, so you might want to give yourself a little bit of negative space between the top and bottom panels to make sure they don’t rub together and cause abrasions. You could also install some durable weather stripping on the top panel to work as a “buffer” between the top panel and all the tolex the panel will contact.

FWIW, I actually prefer the top panel to be open, so I’m in the process of returning my cab to its stock former glory. I get plenty of projection from the two EVM12Ls in the bottom, and the open top gives the cab a little more “breath” that I lose when the top is closed.

I hope this helps!

P.S. did you install the second speaker input? What is it? Does it split the cab into stereo (ie. Two 4 ohm inputs)?