BillFitzmaurice.info

Picked up a new toy on ebay for $50 shipped. Used but tested in good working condition.

I've built BFM cabs before, but this is my first build thread. Figured the best box for the driver is a regular style autotuba at max width. I'm planning to wire the 4 ohm voice coils in parallel for something approaching a 4 ohm load when all is said and done.

Power will be provided by a 600 watt rms X 1 @ 4 ohms profile amplifier. Amplifier is both high/low pass capable. I used this amp on my gto804 TAT and haven't blown it up yet so I think this one will be ok too.

Comments and suggestions are welcome. First question is: is there any reason not to go max width besides the obvious space reasons? My trunk is 36" wide at the narrow point so a 20" wide box should be fine I'm thinking.

I'll be using 2' X 4' sheets of 5 ply 1/2" (acx) from Menards. I've only a sedan to transport them in so any larger sheets wouldn't have fit. They were on sale for $6.50 a piece so actually about the same price as getting the big ones.

Hey Ryan, just a heads up to make sure you inspect those half-sheets very thoroughly...including tapping the entire surfaces to check for large, internal voids.

I had a bad run-in with some of that stuff a while back:

http://www.billfitzmaurice.info/forum/v ... 14&t=10118

Thanks, I'll check on that.

Haven't had too much time to work on it, but so far I cut the side panels (both together at once), and installed panel 1. Panel 1 was bowed, so I screwed a scrap piece to it to straighten it for when it comes time to attach the other panels.

Got panel 2 finished and installed today, after a bit of a headache. One of the driver mounting T-nuts must have been slightly off because the screw wouldn't thread in well then the nut started to spin. I ended up having to take it out and use a new one. The second time it went in without issue. I went ahead and added security screws to the T-nuts so they won't spin once the cab is finished.

This cab is certainly going to be wide for an AT. But I will enjoy the extra output.

Keep up the good work. I am anxiously awaiting your review...

Ryan A wrote: My trunk is 36" wide at the narrow point so a 20" wide box should be fine I'm thinking.

Yes you will be fine. The pressure wave will have plenty of room to propagate.

Well, I've been slowly progressing with the AT an hour here and there, so far up to panel 7.

I'm afraid I made an error though related to the use of ACX plywood. I used the good "A" side of the wood to draw all the lines for the panels, thus making the "C" side the outside of the box. You can imagine my horror when I turned the box around for the first time to look on that side and found a huge knot in the wood on that side panel.

You can save the "You should have used BB" comments...I know, and I will have to live with it. If using ACX and not paying attention, there's a 50/50 chance of installing it the wrong way.

Question is, is there any remedy for the knot or a way to fill it? I've thought about putting an entire side panel's worth of 1/4" board attached to the outside on that side of the box.

Ryan A wrote: Question is, is there any remedy for the knot or a way to fill it? I've thought about putting an entire side panel's worth of 1/4" board attached to the outside on that side of the box.

Fill it with Bondo. Then cover the cab with carpet that matches the color of that in your trunk.

I highly doubt it will present a problem structurally.

lowsound

Thanks, Bill. I will try the bondo. I was kind of hoping to leave it painted or duratexed. If results don't look good enough after bondo, sanding, and painting, I will consider doing the carpet.

What a boob.

iamlowsound wrote:I highly doubt it will present a problem structurally.

lowsound

I don't think so either, I was just worried about cosmetic appearance. It appears the spot is only on the one outer ply.

Ryan A wrote:It appears the spot is only on the one outer ply.

If you want to be anal about it, cut it out with a router set 1/8" deep and fill it with a patch panel or filler. If you Duratex it, no one will know it's there.