Anikun's Auto Tuba Build

[David Raehn]

Your method of cutting the extreme angles is quite similar to what's called a 'sine bar' in the old school art of machining. Look it up, check it out and apply as needed.

[Michael Ewald Hansen]

Here's a side view of the panels glued into place and curing.

Hmm, that cutout looks way too small for the driver.. You sure the surround of the cone clears the baffle sufficiently - would suck to have major cone slap once you are done with the sub and install the driver?

[anikun07]

I think it's big enough. In the picture you're looking at the narrow side, the hole was cut at a 45* angle, so the side facing driver is wider. It took me two passes with the jigsaw after the original cut for me to be convinced enough was cut out.

Today I cut the rest of the panels and braces and put everything in place and glued. Wow, I was surprised that I cut the braces pretty well freehand. I was mostly able to use the strips cut off from my original 3 strips of the sheet of Arauco Ply. Again, though, I had trouble getting the braces to fit while doing a dry assembly. But when it came time to gluing, they went in place much better than when I did my THT. When I cut panel 7, the second panel with a 56* cut, I made a wider 11* base for the ramp. I used 1x6 and ripped it a little inside the edge. Then I used two screws to attach the ramp to the base and used my brad nailer to put two brads into the saw sled. The good thing about the brads is they're so small so I don't have to 1/8" holes in my sled after I'm done making the cut.

Here's a top-down view of all the panels assembled.


And here's a vertical shot of the opening. I know the braces aren't on the same plane, but I was just happy getting them to fit nicely without having to use screws. Clamps worked perfectly, except for the final opening brace. I did have to use one screw to keep it from falling. Besides that screw, one more clamp and it's all looking pretty good.


Tomorrow's task is to cut out the access port on the second side and finish the box. My amp should arrive Friday, so I'm hoping on Saturday I will have it successfully installed. I'm interested to see if I can fit it through my trunk opening. I'm fairly confident it will fit, otherwise it will just be an addition to the back seat.

[anikun07]

Here's a side profile on the unloaded cab.


I put the second side on after cutting out the access panel. I wasn't paying proper attention to the instructions because I cut the opening all the way to the angle. Not a big deal. If someone else happens to do this, the magic number for fitting the angle is 38. I cut a piece to the proper height and the inside half of the piece got cut at that angle. It fit in nicely. Some of the other pieces needed 6* cuts. You'll know which ones when you dry assemble the flange.

You can see the extra long opening. With all the PL I used on those pieces, I don't expect any leaks. The only thing I'm not super happy with is panel 9 got pulled into panel 6 so the second side has an overhang along the front corner.


All that's left is putting the binding posts on an access panel, wiring it to the driver, then cutting off the rest of panel 6. After that it just needs to be installed.

[miked]

Looks great! Don't worry about the braces not being on the same plane. As long as they are BRACING and not rattling, that's all that matters. They need to be "in there". Where, exactly, "in there" doesn't matter.

Have you sorted out your HU/amp situation? Don't forget that if you're installing an amp, you NEED an "install kit." Best Buy sells them as well as any local "car alarm/car stereo place." Or just buy one off EBay.

For a 400W amp, an 8-gauge kit will do. The +12v power wire needs to run directly to the + terminal on the battery, and there needs to be a FUSE within 18 inches of the + battery terminal. That fuse is there to keep your CAR from BURNING UP in case something goes wrong. There are wires inside your toaster. When "too much current" gets passed thru them, you get lots of heat. That fuse is designed to blow and kill the current BEFORE the wire gets that hot and sets something on fire. Like your car. Amps have fuses too. An amps' fuse protects the amp. The +12v power wire's fuse protects the wire/your car. The amp should be grounded back there in the trunk somewhere. It may seem counter-intuitive to not run a "power wire" to a terminal or plug, but trust me on this one. The ground wire is a GROUND wire, not "power." Every electrical system in your car is grounded to the chassis. Your amp needs to be too. An existing bolt somewhere back there in the trunk area is fine. Use a stiff wire brush or wire cup in a drill to rough up the metal where the ground wire (preferably terminated in a ring terminal!) gets bolted to bare, unpainted metal. Hope this helps.

[anikun07]

Thanks, Miked. Yes, that helps. I didn't know there was a kit for it. That should make things easier. I assume it should come with plenty of wire. Are the fuses usually installed on already or do I do that too? I think the manual for the amp recommended 10 ga. wire.

[anikun07]

Update: I ordered the 8 ga. wire kit from Amazon for Saturday delivery. It's still cheaper than going to the auto store for one. Can you tell I really want to hear this play?

[Radian]

For a 400W amp, an 8-gauge kit will do. The +12v power wire needs to run directly to the + terminal on the battery, and there needs to be a FUSE within 18 inches of the + battery terminal.

...but an Auto Tuba will be lucky to see 15V on a good day.

Such is the case...I've had my amp tapped into the power antenna lead (16 ga) for over four years now without issue or sonic penalty.

You can watch the youtube video of my Accord at the very end for proof of that. Another option would be tapping into the courtesy light harness ahead of the trunk lid switch. That way, everything is already fused from the factory.

Power in, power out. If the speaker is only ever going to see 100 watts or less, there's no sense in going bonkers with the wiring, for those still sizing up their install.

[miked]

LOL! A single 8 gauge run from the battery to the trunk is hardly going overboard. I currently have 0-gauge fused with a 250-amp blade fuse, running to the cargo area of my SUV from back in the day when I had 2Kv (2,000 watts RMS) of amplification and signal processing back there. Now, I could get away with 8-gauge but won't be bothered removing the interior of the truck to rewire it. Yes, I was nuts back then. Seriously nuts.

When it comes to electricity, you can never overkill on safety. A piece of 8-gauge is roughly the diameter of a pencil and very flexible, easy to bend and HIDE. I realize that all Bill's designs are super-efficient; that's why I've bought into them. Running PA for 600 people off two amps? Ridiculous, but absolutely awesome. For whatever reason (Class D amp, probably) you've run OK so far tapped off the power antenna lead...dunno how that's possible, but it is not safe at all. And though it sounds good now, you might be surprised at how much better it sounds letting the amp suck power through a larger straw, so to speak.

[anikun07]

I got it working, but nothing is secured down yet. It's the perfect size to fit in the trunk.

I didn't get to do a full test yet because the negative battery connectors broke so I don't have a good connection. Tomorrow after I fix it I'll get to play with it more. For some reason when I try to turn on the headlights everything just shuts off like a fuse broke but removing the negative for a second resets everything and the door ajar light comes up and my roof light works and the radio will turn on too. Odd.

[Tom Smit]

For some reason when I try to turn on the headlights everything just shuts off like a fuse broke but removing the negative for a second resets everything and the door ajar light comes up and my roof light works and the radio will turn on too. Odd.

That's likely because of the broken battery connection, so therefore it back-feeds (and some device says "OK, that's it, I've had too much stress. I quit".

[anikun07]

Yep, $3.50 at the auto store for a nice heavy duty replacement clamp worked perfectly. My subwoofer is now thumping away in the back of the car. I love it! It sounds so much better than having those tiny speakers reproduce LFE that they're just incapable of doing. I have a few more tweaks to do for the installation to be final. Today I taped the main grommet where I poked a hole in the side to push the power wire through - how I saw it recommended on other car forums, and I didn't want to drill the firewall. Does a 50A in the fuse holder seem too big when the amplifier has a 30A fuse? I know the fuse it meant to protect the wire and car, but I didn't know if it should match the amplifier, because if that fuse needs to break I want to know that it will. Next will be putting the RCA cables on the passenger side of the car. I have it next to the power and rem cable, although I don't notice any interference or distortion. Should I leave it as is? I also bought some extra wire loom to put on the power wire where it goes up along the back seat into the trunk. I don't think there are any edges that are inherently sharp, but I'd rather protect the wire even if it might not be entirely necessary. The last thing I need to do is actually mount the amplifier. Since the AT is sinking into the hardboard over the spare tire, I'm considering putting some 1/2" plywood across the trunk so the AT has a nice solid surface to rest on.

[Ryan A]

Were you planning on installing access panel covers?

[67baja]

I didn't realize there is an access hole for the driver on the TrT, just thought the driver screws on the outside of the cab. Skimming over the plans, I don't see any access hole/panel there. Am I missing something?

Edit... Disregard the above. I was thinking he had a TrT. Dont know how I confused that. Carry on.

[miked]

Part of "car audio" involves doing things that make us cringe, like drilling a hole in the firewall. It's not really a big deal, just make darn sure that there's nothing on the other side where you are drilling. And any hole that a power wire is passing thru needs to be grommeted. VERY important! The sharp edge of the hole could wear away the insulation of the wire, wire inside grounds to metal and you have a fire. If you at least wrapped a lot of layers of electrical tape around the wire where it passes thru the hole, that's better than nothing, but still, get some silicone and seal that wire in place from both sides so it cannot move around. It'll also seal the inside from the outside of the car.

A 50-amp fuse to protect the wire is fine. Generally speaking, the power wire's fuse should equal or exceed the total amperage of whatever devices it's powering. The quick and dirty way is to add up all the fuse values on the amps.