Revitalizing the MPV

[MPV TT]

I've been bumping to the same tune since I built and installed my first set-up seven years ago. Needless to say it was time to upgrade my box and my front/rear stage.

I'll be keeping the same deck, and moving those Alpine comp's from the front to the rear.

This was the original box I built out of 3/4" MDF amounting to 3 cubic ft (not including the port area), and tuned to ~27hz. As this was my first box, I had built this box without the knowledge of how I could squeeze out every last dB to tickle the TL, and after hitting 139.6dB, so began my quest for more.....

Loaded up with a 4x8 sheet of Russian Birch 18mm 13ply for a new box.

This is my set-up for cutting the wood. I clamp a 5ft piece of 1x2 aluminum angle as a straight edge, then outfit my saw with a 40 tooth blade. I then employed an old cabinet making trick, and used carpet tape to adhere a piece of whiteboard (any hardwood will do), then plunged through to create a zero clearance cut. This virtually eliminates any tear-out that normally comes with sawing plywood.

This is some pretty wood grain.

Using my home brewed circle jig.

I decided to not use any screws on this box, putting my trust in the glue.

I already had a few clamps, but I needed a bunch more. So I went to Harbor Freight and grabbed a mix of clamps. After all was said and done, only two clamps broke (the plastic pistol grip kind).

Although it may seem sunny, it was a tad nippy and I used a thermometer to keep an eye on the temps to make sure I was within a good curing range for the glue.

Some internal bracing and 45's in the corners.

I moved the operation inside to finish up the box because it was getting too cold.

Using some aluminum shims, I ensured a perfect 3 5/8" port width.

After using my router to round over all the edges I glued on some feet, and cut some reliefs to tuck the vinyl into.

I started with a mahogany stain, then moved onto eight coats of an exterior high gloss polyurethane. I did some sanding about every 3 coats.

Working towards a mirror finish, I wet sanded the poly all the way up to 1500 grit. I then worked the surface with a 3M rubbing compound following it up with a marine grade wax. You can see a pretty good reflection of the scissors on the left.

After gluing the vinyl, and using a bone tool to tuck it in for a nice edge.

I ended up flaring the port like this because of a miscut and a little extra internal volume. In the end, I think it looks pretty sweet displaying the wood grain like this while also reducing the air velocity at the mouth of the port.

All in all, the box is tuned to ~38hz with ~2.1 cuft of space after port, driver, & bracing displacements. I am yet to meter this new box, but after playing around with it, I can say there is a huge improvement over the previous one. It's a much warmer and fuller sound probably due to the use of birch over mdf. It sounds much cleaner, and there is no more audible port noise which became an issue on the last box. It is also tuned much closer to the PeeVee's resonant frequency which means this new box feels great as well.

[MPV TT]

Now onto a front stage upgrade.

These Infinities are rated at 2 ohm which is awesome for this new amp.

The guts of this teenie tiny amp that I will mount to the underside of my seat.

I created a little design in TurboCAD and burned it out of some 1/8" aluminum sheet on my CNC Plasma.

A good amount of dross from burning the aluminum, but some work with my flapper pad grinder smartens it up.

A perfect fit utilizing some OEM holes, it clears the seat slider mechanism and does not infringe on my storage space under the seat.

Soooo small.

[MPV TT]

The Infinity next to the old Alpine which I will move to the back to replace some old Panasonic coaxials.

Same basic size, but you can see some differences.

A much bigger tweeter, but it will fit!

And the crossovers.

Running fresh 12 gauge into the doors. You can also see the two layers of Second Skin on the outer door panel with some strategic pieces on the inner panel that I installed a few years ago.

Sweet tweets, with loads more clarity over my seven-year-old Type-S's

I then moved the Type-S's to the rear. Once I measured out the proper distances I drilled a pilot hole.

I then flipped it over to use my hole saw from the underside stopping once I broke through the plastic, but before I tore up the vinyl. I then flipped it back and used a knife to cleanly cut a hole in the vinyl.

The sound in the van is out of this world. It is great no matter where you sit, especially for those in the back. So far the only downside to the new Infinities is that the tweets are so darn shiny and when the sun hits them right it would blind me whilst driving. So far, gloomy days are working well.

[mttornquist]

holy crap that looks great!

box looks super strong and I love the stained port!

good work my friend!

[MPV TT]

Had an issue with a failed regulator in my BNR alternator. Contacted them, and they sorted it out at no cost to me!