Autotuba x2

[Treo]

My current car seems to be a keeper, so I decided to upgrade the sound system in it. The vehicle in question is a 1999 Toyota Land Cruiser 100, which means there's plenty of space available for a pair of Autotubas. I'm building the regular model, max width, TB W8-740 loaded. Thought it might be fun to document the process here.

Started cutting the sides, and marking internal panel positions.



Ripping the sheet in to 430mm strips. Very happy with the Festool tracksaw. That cheap Nilfisk vacuum has autostart which is handy.



It's good to have a place to sit down and study the plans just one or two more times, just to be sure. Max panel width doesn't leave a lot of room for errors if you plan to use only one sheet of 4x8 per AT. Building in the garage, so lot's of engine parts and other stuff competing for room.



Using a spare amp channel to break in the drivers.



Checking the fit of panel one. Crawling on the floor isn't very ergonomic. I've got a folding workbench on order but it hasn't arrived yet. Yes - that is a grease pit in the background, No I haven't fallen in it. Yet.



Working on the baffle, which took a lot longer than expected.



More progress tomorrow I hope. The system will be powered by a 5 channel class D amp from JL Audio, but I haven't decided on placement yet. Not really looking forward to routing power cables through the firewall and under all the carpets.

[J_Dunavin]

Looks good!
Take your time on that amp wiring, make it look nice! Zip ties are your friend

[CoronaOperator]

Not really looking forward to routing power cables through the firewall and under all the carpets.

Make sure you use a fuse no further than 12" from the battery and use a plastic/rubber grommet to protect the wire going through the firewall. The fuse isn't to protect your amp, it is there to protect you and your car should that power cable get shorted to ground. Without the fuse cutting power to the cable, bad things happen.

[Treo]

Make sure you use a fuse no further than 12" from the battery and use a plastic/rubber grommet to protect the wire going through the firewall.

Yep, I'll make sure to do that. A friend of mine tried what happens if you don't, quickly turned the whole cable into white hot melted copper and smoke. Not pleasant.




Got a couple more panels in place, being very careful to keep things as square as possible. Set it aside to let the glue set, while starting on the sides and panel 1 + baffle for box number two.




Despite having only a 700w motor the little makita has no problem making driver holes. Made an error and ended up with a small notch in the baffle hole but it should not be deep enough to cause any leaks. Gonna test it properly after mounting the driver anyway.

[CoronaOperator]

A friend of mine tried what happens if you don't, quickly turned the whole cable into white hot melted copper and smoke. Not pleasant.

Yep, that's pretty much how I learned too. Hard to steer the car when you can't see and breathing isn't much fun either.

[Treo]

Making some progress. Assembly completed on the first box, except access cover flanges. Started on number two, probably will come together a bit quicker than the first one.

Forgot to take a pic of the saw setup when trimming panel 6, but it worked well, just needs some sanding.



Working on the 56 deg cuts for the next one, cut to 47 deg with the festool, drew a line where the cut would go at 56 degrees, and also made a thin line at the end with permanent marker to see if i was angling the sander correctly. Then sand it down with an orbital sander, took just a couple of minutes.



Result.



Inner panels assembled on box nr 2.



Original plan was to apply Warnex paint with a roller, but since I now have a working compressor in the garage I've started thinking about buying a cheap spray gun and try that instead. No decision on that yet.

[Treo]

Managed to get some things done on the tubas this weekend, first box is leak tested and done. Only paint remaining. Found one leak around the driver, and also one of the covers didn't seal properly at first.

Second box is coming along too, but tonight I ruined my last t10 torx bit which put a stop to things. Gonna buy a couple more tomorrow.

Pic of leak test setup.

[Treo]

Oh yeah, and playing some test tones after the covers were sealed up, this little box had everything in the whole garage rattling along. Can't wait to get the amp installed in the car!

[J_Dunavin]

You may have said already, but what amp are you going to use in the car?

[Treo]

JL Audio XD700/5v2. 4x 75w rms @ 4 ohm + 1x 180w rms @ 4 ohm.

[J_Dunavin]

no high pass option on the sub woofer channel
Perhaps one of these in line, would do the trick?
I like mine !
http://www.audiocontrol.com/car-audio/crossovers/2xs/

[Treo]

Hmm, true but I was under the impression a lot of ppl run the AT without a hp filter ?

[Bill Fitzmaurice]

Hmm, true but I was under the impression a lot of ppl run the AT without a hp filter ?

For the most part a HP isn't needed, as there's not much content in most music below the AT pass band. If you're in the habit of playing music with lots of content below 35Hz at high volume then a 40Hz HP filter is advisable.

[Treo]

habit of playing music with lots of content below 35Hz at high volume then a 40Hz HP filter is advisable.

I'm quite heavily into most genres of EDM so yes, I guess I'll have to take that into consideration then. Thank you.

Completed basic construction of the second AT today. Also decided on amp location, under the passenger seat. There's about 5 inches of space under there so temperature shouldn't be a problem, and also wire lengths are minimized. However with christmas coming up the project will be at a standstill for a few days. Hopefully the weather will stay as unusually warm as it's been until now since work on the car will have to be done outside. My garage doors are to small for the big land cruiser.

[Treo]

Well now! I got the other AT completed and leak tested. Made sure they were both wired with the same polarity. Put some spray can primer and then rolled them with Warnex, that amazingly hadn't hardened in it's jar despite sitting in my garage for over five years. Did all the wiring in the car, which was a royal pain in the behind. Front speakers were already in the car, a 2-way component system from Swedish maker DLS. Rear doors were stock toyota plastic 20w elements that i gutted and used their frames to mount new 6.5" 2-way coaxes from Hertz, just for some more power handling and mid bass kick. The tubas i laid next to each other in the rear, firing towards the tailgate. How does it sound ? Well, still experimenting with settings, crossover at 90Hz right now, and set the gains according to the amp manual at 17.3 V for mains, and 28.6 V for the sub channel.
Generally I'd call the sound tight. Clean. Musical. Snappy. Pretty well balanced. Not super "shake the mirrors and eye-balls" loud, but it's a big cabin to fill. Still battling a response dip centered around 75Hz, tried switching polarity on the subs which made it a bit better, but it's still there. Apart from that I'm pretty happy. Oh, and I have to find a way to damp out some crazy vibrations in the outer doorhandles.