Autotuba loaded with a JBL GTO804

[Michael Ewald Hansen]

Nice build, pretty much done in two days! How easy is it? I could build one from the scrap ply of my TT...

Well, even though it looks nearly finished, i'd say im about halfway there - considering I still need to fit cover, glue side, fit binding posts, need to fill it, sand, prime and then paint the thing

Its a pretty easy build - when you're done with your TT, i'm sure you could build one quite fast.. I'll let you know of performance when doing it as narrow as I am.. i've used about 3/4 of a 4x8 piece of ply..

@Phaedras-are you glueing up in the cold? How is the glue holding up? Pretty quick build, though.

@bassmonster-AT is easier than a TT in my opinion(built both at 16" wide total)

Yea, i'm gluing in the cold and its terrible. Along with the low humidity the glue cures SLOOOOW when outside.. So im pretty careful not using too much PL so it doesnt smear all over and when i'm done building I carry it inside for curing..

[Michael Ewald Hansen]

So, day 3!

The money shot!


Spraypainted the back of the mouth fast as it doesnt need to be primed etc as noone is going to notice anyway..


Squuueeeeze out is always good.. I'm not using a tonne of PL but trying to get a very even bead so the squeeze out is consistent!


Side mounted and fastened tight! Gonna leave screws in and just cover them..


Might aswell fill out imperfections and let that dry along with the PL!

[bassmonster]

Nice, that's gonna look sick when it's done.

[Spoon]

I'm sure even that narrow you're going to have some bone jarring bass. Plus with your small car you'll have massive cabin pressure. Lookin' good! Keep the pics coming!

[bassmonster]

Needs moar update, again.

Warning on the gasket. It's not ideal, although big and it compresses some when you tighten down on it. I ran a bead of latex caulk around the edge of the baffle before mounting the drivers for the final time, just in case, and when I tightened the drivers I honked down on them hard. No leaks so far. Also, my baffle was very rough, with wood filler in many spots to repair the chipping from the old jigsaw blade.

[Michael Ewald Hansen]

Needs moar update, again.

Warning on the gasket. It's not ideal, although big and it compresses some when you tighten down on it. I ran a bead of latex caulk around the edge of the baffle before mounting the drivers for the final time, just in case, and when I tightened the drivers I honked down on them hard. No leaks so far. Also, my baffle was very rough, with wood filler in many spots to repair the chipping from the old jigsaw blade.

Sorry for slooooow updates, when the cab was put together I wanted to test it in the car and was bummed out because:
1. Either something wrong with my amp.
2. Need to use high level input on the amp as there is no lineout on the radio.
3. The high level input sensitivity voltage is higher on the amp than the radio is capable of..

Anyways, I walked away from the project for a little while to not get frustrated.. So the cab was just sitting there for a while.. However, I made progress today! And i'm going to use it at home until i figure out what to do with the amp..

Sanding.. I bought a cheap Belt Sander before my OT and T39 build and I still love it.. Makes sanding uber fast - leaves stripes, but it doesnt matter as the duratex covers it perfectly in the first layer.. Would use a regular excenter sander or something similar if I'd paint it in anything other than duratex..


More sanding!


Priming the mouth as im just spraypainting it and it looks much better primed.. Single layer oil based primer is fine for this - noone is going to see it anyways, haha..


First layer of duratex.. Got a small heater in the room which easily heats it to around 40-50 degrees celcius, so the duratex cures FAST!




I did test it out today on a crappy 5.1 surround sound set made by philips.. Just switched the sub and - lol - made a HUGE difference even though its so narrow.. The whole setup sounded way better..

[Michael Ewald Hansen]

Gave it a quick spray.. It doesnt need more than one spray - perfect coverage when primed!

[Gregory East]

Are you tapping the speakers for your high level signal?

What's the amp? There should be input level control.

The pic isn't too clear but it looks like the mouth brace didn't get glued on properly? Great potential for buzzing.

[Michael Ewald Hansen]

Are you tapping the speakers for your high level signal?

What's the amp? There should be input level control.

The pic isn't too clear but it looks like the mouth brace didn't get glued on properly? Great potential for buzzing.

The car head unit has 4 speaker outputs.. The front speakers use 2 and the other 2 I send to the amp.. The amp has 4 channels and im bridging one to get more out of it. Each channel pair has L G R high level inputs, so I reckon both channels need the l/r signal and share the ground signal from both?

The line sensitivity is 0.15-5v and the high level input sensitivity is 2.5-7v.. When playing at normal volume i measured around 0.2-1v..

Im probably doing something wrong, as it would be weird if all channels on the amp is dead!

The amp is this: http://www.monacor.dk/produkter/bilster ... nr/142790/

There is a small cap between the brace and the mouth in the sides, however glue does connect in the center of the brace all the way to end and the brace is glued on firm - no rattling and its not loose at all - so its mostly aesthetic.. Tested the cab at up to around 15-18v and there was no buzzing at all

[CoronaOperator]

Each channel pair has L G R high level inputs, so I reckon both channels need the l/r signal and share the ground signal from both?

Very bad, do not use the speaker level inputs if they use a common ground as your head unit utlilizes a floating ground. You'll short out your head unit twisting wires together. Use an aftermarket Line Level Converter.

If you suspect your amplifier not working properly, test the line level inputs with a mp3 player.

[Michael Ewald Hansen]

Sooooo, I feel stupid and relieved at the same time.. I started doing some troubleshooting today and one of the things that had bothered me was that the on LED had a feint glow which was the same no matter if the ignition was on or off, so I found a tip in the manual to try and short the REM and BATT to see if the control voltage from the radio was working properly.. As you might have guessed, the amp turned properly on and the LED lit up much better than before.. So I pulled out the head-unit - and yes, the control voltage was hooked up wrong. Changed it, hooked it up to the amp and it turned on immediately when I turned on the ignition.. So i'm a happy camper!

Excited about this development I proceeded into testing the amp with sub and the speakers I bought - and boy oh boy was I not dissappointed.. Even though I built it 11" wide as that is the absolute MAX I can fit, the AT pounds in a small car like that.. Its the same clean bass i've come to love about the T39's.. Put it through its paces with everything from dubstep, to trance, rock, pop whatever had a beat and it performed admirably! Ill post a few pictures of the sub installed permanently in the car soonish

Here is a pic of the finished sub:

[88h88]

I like the Bose advert in the pic

That looks really nice. Awesome work. We getting some video?

[Michael Ewald Hansen]

I like the Bose advert in the pic

That looks really nice. Awesome work. We getting some video?

Haha, hadn't noticed that..

Thanks a lot.. Im excited about the result considering how few hours I've spent building it.. Think I got something like 12 hours build time with finish etc if I count out the time I spent contemplating what was wrong with the amp and the install in the car..

I'll shoot some video some time soon

[Spoon]

Great job Phaedras!

[bassmonster]

Nice, looks sick.