DIY Subs are nearly there!

Just been to put some final touches to my new subs at my mate's workshop today.

Boy are these big muthas I have asked WM to post some pictures, as I don't have the facility. We are now at the stage of applying the wadding. As a first go I have used Dacron, getting fibreglass was impossible in the UK sadly. the 9oz fibrefill expnds to about 19mm, which is a problem. Do I use double layers or try it with just the one An alternative would be 1" foam, but Falcon are out of stock and I cannot get any from elsewhere. So we'll start off with the Dacron.

The cabinet is built using 25mm MDF, with a 38mm front baffle. The extensive bracing is fitted to grooves in the sidewalls, and all joints use biscuits, glue and screws. We wnt for the sloping sides as much to reduce the apparent bulk as to help with standing waves.

The cabinets weigh at least 60lbs each, and that's before we put the 40lb drivers inside

So any thoughts on damping would be helpful and might save hours of trial and error! Should I wrap Dacron around the braces or will they be OK left as they are?

Cheers

Michael

 

im no expert at all
but i would think of wrapping the braces, maybe use cable ties or chicken wire to do the job.
sounds wicked tho, cant wait to see the pics!

 

Michael,

Pity you can't get hold of the foam, you have to be careful with a reflex design that you do not obscure it's function with excess wadding, especially in the area of the vent. I would say that though design - sloped sides and plenty of bracing - that you will have negated the problem of standing waves considerably. Although as you are (still are, I assume) using a wide bandwidth design, then a small application may well be necessary.

What I would say, though, is that it is difficult, if not impossible to give a universal answer, so some trial and error may be innevitable. Therefore, what I would do first is to listen to them in isolation - ie listen to the enclosures, and see what they do. It also give you an opportunity to check for panel resonances and air leaks. Both are pretty unlikely given the professional construction, but not impossible - and a very definite cause of sonic degredation.

One final point - how did you decide to hold the drivers in place? My suggestion would be pronged tee nuts. You need to be very careful with the diameter of the baffle cut-out (ignore the manufacturers suggestion in this area, and measure it yourself), in order to leave sufficient material for the tee nut to be used in. But, when so done, the use of bolts is more secure, and if they work loose, they can be check-tightened - screws have limits in this area. Also, they allow for the drivers to taken out for test purposes, without impacting on the quality of refitment. Oh, and if you use allen-head bolts they look good too

 

Hi Test Tone,

I decided to use BAF wadding, as this appears to be less dense than the Dacron doubled over. The cabinet seems fairly inert.

The JBL drive units only accept 4mm Hex Bolts , eight of them per unit. Picked up some 4mm tee nut type things from my friends at Proac, they do not have prongs, but seem quite neat. There's plenty of room to use then on the 19mm wide sub baffle. I have also ordered some RDC cones to isolate from the floor, using 6mm Tee bolts to fix to the cabinet.

Thanks once again for all your help

 

Michael,

Looks like you've got all bases covered. It'll be great to see a few pictures...

 

Hope so WM posted the pictures of the bare cabinets over on the main forum under the Rollin Thunder heading Hopefully get some piccies of the finished articles early next week