Dual 8" Truck Tuba

[CarterKraft]

We finally started building a BFM design.

I bought a sheet of 1/2" imitation BB from lowes the last time I picked up some wood for a laundry room remodel I am doing.
It's not the best but it will have to work this goround.

For the Jack Lite and the rest of the cabinets I am going to try and get real BB from a local plywood supplier.

This Truck Tuba is for moms SUV or the 16 year old's room if we get in trouble putting it in the SUV.
I was showing my son the thread by @iSurfSouthChinaSea and we noticed @Sethrocksyou' version with the derivers on panel 1 instead of on the face.
We really liked that placement as it would help protect them from abuse when it's laid on its side in the rear of a SUV.

This was my first time actually building from a BFM plan and I have to say it is completely different actually building the box from the plans instead of just looking at the plans. I am fairly technically minded but just reading the plans had me confused and even discouraged but one you start cutting and laying it out it really is pretty straight forward and went really fast to get all the pieces cut.

I stopped on the way home tonight and got the PL Premium so hopefully tonight we can start gluing.

I do have a question though about panel bracing with the 7.5" panels and dual 8" MCM as Seth has done.
It says in the plans we don't need the braces but does that hold true when using dual drivers under 8" panel width?
I can only use one if that's recommended.
I am going to add a panwel support from the front to rear as in the original plans call for.

[CarterKraft]

We are going to start out with some old 8" RadioShack closeouts I have then order the MCM's as needed.

[Bruce Weldy]

We are going to start out with some old 8" RadioShack closeouts I have then order the MCM's as needed.

If they aren't designed as subs - you'll probably blow 'em on the first note......probably not nearly enough xmax for sub duty. But, who knows.....if you don't mind blowing 'em up - have some fun - and shoot video!

[CarterKraft]

We definitely don't mind HAHA.
They were $9 each when Tandy Outlet were liquidating the last of their inventory after Chapter 11.

I put them in a home brew isobaric ported cylinder cabinet in the early 2000's and they sounded like garbage, they sat on a shelf ever since.
I would love for them to leave in blaze of glory.

[Seth]

We finally started building a BFM design.

I bought a sheet of 1/2" imitation BB from lowes the last time I picked up some wood for a laundry room remodel I am doing.
It's not the best but it will have to work this goround.

For the Jack Lite and the rest of the cabinets I am going to try and get real BB from a local plywood supplier.

This Truck Tuba is for moms SUV or the 16 year old's room if we get in trouble putting it in the SUV.
I was showing my son the thread by @iSurfSouthChinaSea and we noticed @Sethrocksyou' version with the derivers on panel 1 instead of on the face.
We really liked that placement as it would help protect them from abuse when it's laid on its side in the rear of a SUV.

This was my first time actually building from a BFM plan and I have to say it is completely different actually building the box from the plans instead of just looking at the plans. I am fairly technically minded but just reading the plans had me confused and even discouraged but one you start cutting and laying it out it really is pretty straight forward and went really fast to get all the pieces cut.

I stopped on the way home tonight and got the PL Premium so hopefully tonight we can start gluing.

I do have a question though about panel bracing with the 7.5" panels and dual 8" MCM as Seth has done.
It says in the plans we don't need the braces but does that hold true when using dual drivers under 8" panel width?
I can only use one if that's recommended.
I am going to add a panwel support from the front to rear as in the original plans call for.
20201213_203223.jpg

Hey Carter, good for you. You chose a good one for your first build. TruckTuba is even easier than the AutoTuba.

The problem with the ply with a thin outer veneer is that that thin layer tends to separate from the thicker ply's below. I'd recommend any grade of home improvement store ply (which isn't the ply recommended in the plans either) with at least 5 equal thickness layers over the thin veneer stuff any day of the week. I used CDX siding ply for my TruckTuba, a little less than $20 sheet IIRC. Lot's of knot's to fill, but got a nice finish surface with enough filling and sanding. But, you have what you have, so let's move on. Hopefully she serves you well and doesn't have delamination issues.

You still want to brace from one 24x36 side to the other in the driver chamber at the locations that they would be if you were to use the standard speaker location. I also added a gusset/brace between the drivers, tying both sides into panel 1. Was only a 3"ish x 7½" piece. But, it's definitely not as important is the side to side bracing in the middle of that chamber. On Bill's recommendation I added mouth bracing for added support on panels 6 and 7, which are also driver chamber panels.

[CarterKraft]

MS paint cad version of possible brace locations.

I will center the bottom 1/side/side panel between the drivers but does the angle and or length into the driver chamber matter?

edit: Looking at the Sketchup plans I see the braces from the 10" version will work fine so I will just replicate all those.
The only detail I will need to determine is the driver compartment bracing, if one centrally located is enough or if it should bisect the compartment and extend more than half way across the chamber or if it should be two panels as in the original plan.

[Bill Fitzmaurice]

Use at least two braces to connect the sides. The point is to make the unbraced spans as short as possible.

[CarterKraft]

Thanks Bill, I will lay it out as even as possible.

[Seth]

I had already built mine per the plans when I changed course and put the drivers in the side. So, the driver chamber bracing was per the plans, straddling the driver flange. I lucked out, and was able to space and fit the drivers on panel 1 without the magnets interfering with the existing bracing.

In placing your driver chamber bracing, use multiple braces and try to space them so that there's less than 8" of side panel between bracing and other intersecting panels (1, 2, 6, & 7), while also making sure you have room around your driver location to clear the magnets.

[CarterKraft]

I had already built mine per the plans when I changed course and put the drivers in the side. So, the driver chamber bracing was per the plans, straddling the driver flange. I lucked out, and was able to space and fit the drivers on panel 1 without the magnets interfering with the existing bracing.

In placing your driver chamber bracing, use multiple braces and try to space them so that there's less than 8" of side panel between bracing and other intersecting panels (1, 2, 6, & 7), while also making sure you have room around your driver location to clear the magnets.

That's what I was thinking about doing. I was gonna use a compass and scribe lines at the 7" ish distance from each panel to get me the best layout possible.
Did you double up panel in the driver mounting locations as per the plan on the side. My gut says that isn't needed, I will add the screw doubler blocks though.
I may actually double it up know thinking about it because I could then flush mount the drivers for more protection.

Lastly do you think two 8's is needed is one one plenty. Like I said we are going to cut one hole at a time and add the driver I already have for fun sake.
realistically for the mom mobile a 10" bass reflex would be more than enough. If one 8" is near that level I may need to quit while I am ahead.

[Seth]

That's what I was thinking about doing. I was gonna use a compass and scribe lines at the 7" ish distance from each panel to get me the best layout possible.
Did you double up panel in the driver mounting locations as per the plan on the side. My gut says that isn't needed, I will add the screw doubler blocks though.
I may actually double it up know thinking about it because I could then flush mount the drivers for more protection.

Using a compass sounds like a great solution

It's too bad we didn't chat about this before cutting your panels... I would have liked to recess the drivers, but on a 7½" panel, 8½" overall width cab there's just so little room to do so. It is possible, but the edge of the drivers circumference would be carved into the side panels and possibly/probably intersect with a ¼" round-over and create a thin spot on the edge that could be susceptible to damage. So, no, I didn't add the driver flange. I just surface mounted the drivers. If I were to do it again, I'd go at least another ½" wider and probably a full inch minimum. If you give it a go, you'll have to do it after the cab is buttoned up with the double thick panel 1, be spot-on perfectly centered, and route the outer recess to depth and width before cutting out the hole. Also, I'd make sure to cut the hole sized for the MCM driver if it's different than the drivers you have on hand.

Here you can see how little room there is on the edge with a 7½" panel.

(The original driver placement hole on the side in this photo was plugged, filled, and sanded flush)

Lastly do you think two 8's is needed is one one plenty. Like I said we are going to cut one hole at a time and add the driver I already have for fun sake.
realistically for the mom mobile a 10" bass reflex would be more than enough. If one 8" is near that level I may need to quit while I am ahead.

Two 8's is definitely not needed. I just added the second because I had it on hand already. But, I would recommend it just because... for $30-$35 additional, why not?

[CarterKraft]

No sweat, I wish I would have asked you too.
I literally changed to your design after seeing it out in the shop showing my son.

It's no biggy if it doesn't work out I can make a outside doubler with cutouts, even if they don't entirely surround the drivers they will provide some protection.
I have the jasper circle cutter so precise holes are pretty easy.

I was worried you would say that about the second driver haha.

[Seth]

No sweat, I wish I would have asked you too.
I literally changed to your design after seeing it out in the shop showing my son.

It's no biggy if it doesn't work out I can make a outside doubler with cutouts, even if they don't entirely surround the drivers they will provide some protection.
I have the jasper circle cutter so precise holes are pretty easy.

I was worried you would say that about the second driver haha.

I will probably add a a custom exterior protective grill to mine too. I look forward to seeing how you do yours.

[CarterKraft]

More progress.
We got all the braces (I hope) in and glued as well as the doubler plate for panel 1 driver inset if possible. It looks like it will work but without the mcm driver on hand I can't confirm any of that. The side to side braces provide a maximum span of 5" to any panel. Looking at the pix today I might need to add another support for that corner to reduce the span.

We rounded over all the port mouth braces and even coped the two braces at the mouth for extra style.

We should be able to glue the lid on tonight and layout the first driver hole.

[Seth]

Looks good. You guys are a-mov'n and a-shak'n. What a great father son project

I see you gus put your mouth brace flush with the face of the mouth. The mouth brace dimensions in the plans place it squarely in the middle of panel 7. Probably not a real big concern, since your panel width is only 7½", but it wouldn't be a bad idea to make a triangle piece and glue it in to give more support to panel 7.

Over the past few minutes of writing this reply and editing the photo I've realized it's probably not a big enough deal to worry about. Especially since the plans don't have panel 1 braced in the driver chamber at any width. If you're inclined, go ahead and put a triangle in there, otherwise don't sweat it.


Looking forward to your review. Honestly, Mom should love it too.