Armortek

hello all,
not being an expert in acoustics, and building a speaker box for my Sherman, i want to build the box so that armortek supplied speaker just fits in the box but thinking about it is it best to build the box with a fair amount of room around the speaker so you get a better sound, any ideas/thoughts.

Chris.

There's not a lot of room inside the Sherman for a speaker!

The box needs to be big enough, or vented, to allow the speaker to compress the air inside, but still prevent sound waves from the front and back of the speaker from cancelling each other out.

I've tried a couple of sealed marine speakers at the rear of the engine bay but they were only a couple of inches across and couldn't handle the power needed.

I purchased one of my Shermans with the speaker mounted in a large square ABS box in the turret well and although it sounded good it meant it wasn't possible to traverse the turret when the gun was elevated. That wouldn't be a problem if you don't have the blank firer fitted though.

Elliptical speakers supposedly give the best all-round frequency response in a single speaker, so it may be possible to mount a couple of those on the sponsons by the turret.

I've also wondered about laying the batteries (I use 20AH AGM ones) flat on the floor and mounting the speaker(s) and control electronics above them. Not sure how badly this would affect the accessibility of everything though.

Adrian.

hello Adrian,
thanks for the reply, originally i mounted the speaker on the o/s panier side shelf at the rear, as the speaker then is under the engine grill but because the small gap i had to mount the speaker in a metal cradle, i could make a wooden box but it will have to be the size of the speaker and dont know if this would effect the sound, i could mount it on the floor under the turret in a bigger box as my batteries lay on there sides on top of each other so there is room.
cheers, chris.

Chris,

What brand/type of speaker are you using ?
With the information you can find on most manufacturers sites, you can calculate the required/optimal contents of the box for your speaker.
But whatever, any box is better than no box at all

Chris,

Speaker boxes are a bit of a black art. Wooden boxes seem to work well but to get the true sound from the box you've made you must mount it in the tank with the turret and all hatches fitted as these metal hulls do cut a lot of the sound down. Another way to do it is to buy some mid range computer speakers from Argos or the like and use these in their supplied boxes as they give good sound. A naked speaker is not good.