# 13 Cubes in a 1994 GMC Sierra



## TJ Mobile Audio (May 6, 2009)

This is not my vehicle, but I'm doing all the work, so I think I deserve to take credit.

Starting with the design/conceptual stage:










We considered a tapped horn, but decided to go with something a bit more conventional:










Here are the specs, subject to change:
10.1 cubic feet NET, 12.8 CF gross
5.05 CF net per chamber
34 Hz tuning
SPL XL2-1600 amplifier
4x Vibe 12" level 2 subwoofers
Soundstream 4x6" speakers
Clarion CD deck

That was day one.


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## TJ Mobile Audio (May 6, 2009)

Day two:



















Those cross pieces are just braces, and supports for the port.

Here's how the ports are arranged:


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## TJ Mobile Audio (May 6, 2009)

Day three:

Installed baffles, added more bracing, cut some holes with a router. This box will hold four 12" subwoofers:










That's a kitchen chair and a standard 4x6" speaker in the picture for scale.


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## TJ Mobile Audio (May 6, 2009)

Day four:

Installation prep day. Put top plate on box. Stripped back seat. Scribed contour of floor onto skirt-board. Cut skirt-board with jig saw, attached skirt-board to box.

Here's a picture of the customer's current equipment, which was between the front seats and the rear seats. Mismatched subs with a Jensen amp, 'nuf said. In the picture it's sitting where the new box will go.

We'll call this "before":










Here are some pics of the skirt board:



















Here's the box without the skirt-board:










That's a 2-liter bottle and a standard 6' 8" door for scale.

Installing the skirt-board:










Box with skirt-board installed:










I promise the box isn't bowed like that, it just looks that way because my zoom lens was adjusted wrong.


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## TJ Mobile Audio (May 6, 2009)

The box finally went in on Saturday, it sounds and looks great. It's clean sounding, but also very loud. The single pair of 4x6" Soundstream coaxials in the dashboard locations do a surprisingly good job keeping up with the bass. The system puts out much better treble and mids than I had expected.

Here's a link to the video on YouTube, I'll pics when I get some more time. YouTube - 4x Vibe 12" Subwoofers, 13 Cubes, GMC Sierra Extended Cab


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## Aznattic (Jul 4, 2007)

Never really heard of the subwoofers but that is good looking box. 

Thought there would be more flex though lol.


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## BLAMM0 (Feb 25, 2008)

i'd love to have that premier subwoofer, already have one, but getting a second is hard, because they're old


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## DaveRulz (Jun 22, 2006)

really? four 12's and a pair of 4x6's? do you have an amp on the 4x6's? do you have ANYTHING for midbass?


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## TJ Mobile Audio (May 6, 2009)

Aznattic said:


> Never really heard of the subwoofers but that is good looking box.
> 
> Thought there would be more flex though lol.


They're made in the UK, I hadn't heard of them either, but the price was right. As for the flex, they could take a much larger amp, they can handle 450 watts RMS each, and they are currently only getting about 200 RMS each. But it's loud as hell (and hell is very loud, they say) so I doubt the guy will want to upgrade.



DaveRulz said:


> really? four 12's and a pair of 4x6's? do you have an amp on the 4x6's? do you have ANYTHING for midbass?


Yes, I built it for a customer, the midbass is a bit lacking, but there is definitely some. The dashboard locations help, plus the 4x6's have a 91 db efficiency rating while the subs are only 89... But I don't think he wanted an entirely balanced sound.  There's currently no amp on the 4x6's, but they could take 125 watts RMS each if we need them to in the future. I think that would do the trick!


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## RavynX (Jun 22, 2009)

That's definitely some bass but it's hard to hear since I think the camera microphone wasn't all that great; lots of distortion and buzzing in the video. You can definitely see the different parts of the car shaking though. I hope they don't spend too much time in that vehicle. :laugh:


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## TJ Mobile Audio (May 6, 2009)

RavynX said:


> That's definitely some bass but it's hard to hear since I think the camera microphone wasn't all that great; lots of distortion and buzzing in the video. You can definitely see the different parts of the car shaking though. I hope they don't spend too much time in that vehicle. :laugh:


It's his work truck, so it'll get a lot of use. I taught him how to use the volume knob though, and made him sign a waiver in case he goes deaf or rattles the car apart! It gets uncomfortably loud, so I know I'd turn it down most of the time if it were me. By the time I was done fine-tuning the amp and shooting all the videos, I was almost sick to my stomach from all the vibration, and I've heard plenty of loud systems before. This one made it into another ballpark, compared to most of what I see in lowly Idaho.

Sorry I don't have a better microphone, it's hard to pick up anything above about 110 dB, and this is probably well into the 140s. We might have it metered this summer just for fun.


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## RavynX (Jun 22, 2009)

TJ Mobile Audio said:


> It's his work truck, so it'll get a lot of use. I taught him how to use the volume knob though, and made him sign a waiver in case he goes deaf or rattles the car apart! It gets uncomfortably loud, so I know I'd turn it down most of the time if it were me. By the time I was done fine-tuning the amp and shooting all the videos, I was almost sick to my stomach from all the vibration, and I've heard plenty of loud systems before. This one made it into another ballpark, compared to most of what I see in lowly Idaho.
> 
> Sorry I don't have a better microphone, it's hard to pick up anything above about 110 dB, and this is probably well into the 140s. We might have it metered this summer just for fun.


Wow, that's definitely a lot of vibrations to make an audio installer sick to their stomach, haha. I'm glad you got the customer to sign a waiver; good thinking.  Is it a camera in video-mode or a camcorder that you're recording on?


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## TJ Mobile Audio (May 6, 2009)

RavynX said:


> Wow, that's definitely a lot of vibrations to make an audio installer sick to their stomach, haha. I'm glad you got the customer to sign a waiver; good thinking.  Is it a camera in video-mode or a camcorder that you're recording on?


I was in there for about 25 to 30 minutes, and that's all my stomach could handle. I shot the video on my brand new Fuji Finepix J20, it's a point-and shoot digital camera, but it has a pretty good video mode. The video is mostly to show the installation work. When recording videos at high volumes, the sound quality will never come through accurately unless you have an auxiliary mic that's less sensitive than the built-in one. Same is true for camcorders. They're designed to pick up everyday sounds, so about 60 to 110 dB.

I've considered taking two videos, one with the volume up so you can see the effects of the output, e.g. window shake, etc. and one with the volume down so you can hear the sound quality, then dub the sound from the second video over the image from the first and no one would know the difference. I've never felt like going to that effort, but I might do that next time I record my own system.


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## RavynX (Jun 22, 2009)

TJ Mobile Audio said:


> I was in there for about 25 to 30 minutes, and that's all my stomach could handle. I shot the video on my brand new Fuji Finepix J20, it's a point-and shoot digital camera, but it has a pretty good video mode. The video is mostly to show the installation work. When recording videos at high volumes, the sound quality will never come through accurately unless you have an auxiliary mic that's less sensitive than the built-in one. Same is true for camcorders. They're designed to pick up everyday sounds, so about 60 to 110 dB.
> 
> I've considered taking two videos, one with the volume up so you can see the effects of the output, e.g. window shake, etc. and one with the volume down so you can hear the sound quality, then dub the sound from the second video over the image from the first and no one would know the difference. I've never felt like going to that effort, but I might do that next time I record my own system.


Ah cool, makes sense. I'll have to see how my new sound setup is when I record it on my Canon HG20; it'll be no where near 140dB let alone past 100dB, haha. I've been thinking about getting an upgraded microphone for the camcorder anyway.  Yeah, definitely get some video with the volume down so the camera can pick up the quality of the sound.  Gotta show off your skills, right?


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## TJ Mobile Audio (May 6, 2009)

RavynX said:


> Ah cool, makes sense. I'll have to see how my new sound setup is when I record it on my Canon HG20; it'll be no where near 140dB let alone past 100dB, haha. I've been thinking about getting an upgraded microphone for the camcorder anyway.  Yeah, definitely get some video with the volume down so the camera can pick up the quality of the sound.  Gotta show off your skills, right?


Are you just running component speakers in that little S2000? You've got an amp on them, according to your sig, so 100 dB is really not all that loud. If your components are 91 dB efficient, for instance, and you're listening at 1 meter distance, that means 91 dB @ 1 watt, 94 @ 2 watts, 97 @ 4 watts, and 100 dB @ 8 watts. And that doesn't factor in cabin gain. Pretty sure you can break 100, lol. Have you posted a build log?


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## RavynX (Jun 22, 2009)

TJ Mobile Audio said:


> Are you just running component speakers in that little S2000? You've got an amp on them, according to your sig, so 100 dB is really not all that loud. If your components are 91 dB efficient, for instance, and you're listening at 1 meter distance, that means 91 dB @ 1 watt, 94 @ 2 watts, 97 @ 4 watts, and 100 dB @ 8 watts. And that doesn't factor in cabin gain. Pretty sure you can break 100, lol. Have you posted a build log?


Hehe, don't want to jack your thread here :laugh: but... nope, haven't posted a build log yet; I'll put one up this afternoon or at least by the weekend. I'll have to make an after-video to complement my before-video with the blown stock speakers from the previous owner.


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## TJ Mobile Audio (May 6, 2009)

Stripping the interior, installing 4 gauge wires, and mounting the amp. I furred up the uneven parts of the floor with OSB plywood to give the amp a level, secure surface.




























We did eventually hide those RCA interconnects, but I'm having trouble with photobucket at the moment so I can't show a picture of that.


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## TJ Mobile Audio (May 6, 2009)

I'm going to emphasize that there were very very tight clearances getting this box in. It took me and one other guy over an hour just getting the box into the back of the truck, and another half hour to position it perfectly. This box is flush-mounted on four sides (left, right, bottom, and back) so that added a layer of difficulty.


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## TJ Mobile Audio (May 6, 2009)

We tested one side of the enclosure before mounting it, and determined that we needed to fine-tune the internal volume with spray foam. We reduced the volume on each side by 0.1 CF, so we now have just over 5 CF net each side.


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## TJ Mobile Audio (May 6, 2009)

Here's the first picture with the subs all wired up and installed. It's kind of dark, but gives a good idea of the size of the enclosure. In fact, with the box installed, it's next to impossible to take a picture that shows the whole thing.


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## TJ Mobile Audio (May 6, 2009)

Let's do a little before & after comparison.

Before:










After:


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## sinister-kustoms (Jul 22, 2009)

Man that thing is mammoth! I bet it pounds!


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## arrivalanche (Jun 27, 2008)

what about the power wire?


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## TJ Mobile Audio (May 6, 2009)

sinister-kustoms said:


> Man that thing is mammoth! I bet it pounds!


Indeed.



arrivalanche said:


> what about the power wire?


It's 4 gauge.


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## fallbrookchris (Feb 13, 2009)

will there be any side beauty panels? With a little more work this could be a really nice looking install...got to give it to the owner, he is either nuts or trying to make up for something, regardless of what his motivation was he will soon be deaf, cool build!


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## keep_hope_alive (Jan 4, 2009)

nice box. that configuration is always guaranteed to slam. also, you know that it would be difficult to steal  i assume you bolted it to the truck floor? don't tell us where, you don't want that on the internet. 

but a pair of coax 4x6? come on, that is just plain silly to pair up with those subs. make sure your friend gets an amp on at least on good pair of speakers. 

no offense, but you don't know what midbass is if you think a dash 4x6 has any whatsoever. my guess is that the system is completely lacking between 100Hz and 200Hz.


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## TJ Mobile Audio (May 6, 2009)

fallbrookchris said:


> will there be any side beauty panels? With a little more work this could be a really nice looking install...got to give it to the owner, he is either nuts or trying to make up for something, regardless of what his motivation was he will soon be deaf, cool build!


Probably not on the beauty panels. It was a low-budget install, so to speak. As it is, he's completely thrilled with the installation, he said he's never seen anything quite so custom. His wife even likes the system, and want me to build one in her car, woot!



keep_hope_alive said:


> nice box. that configuration is always guaranteed to slam. also, you know that it would be difficult to steal  i assume you bolted it to the truck floor? don't tell us where, you don't want that on the internet.


Thanks, it does slam indeed. It's secured in several places, but even if it weren't there'd be no way it could come out in less than two hours. You'd have to remove the front seats and disassemble a good portion of the interior. It was a two-man job getting it in and took nearly 90 minutes just to get it in place, and that was before mounting the four subs. The box alone weighs about 180 LBs, and the subs add another 60. The subs and amp are secured with special screws as well, so any would-be thieves will have to look elsewhere. The back windows are tinted, so surprisingly enough, a casual observer would not even notice the box is there!



keep_hope_alive said:


> but a pair of coax 4x6? come on, that is just plain silly to pair up with those subs. make sure your friend gets an amp on at least on good pair of speakers.
> 
> no offense, but you don't know what midbass is if you think a dash 4x6 has any whatsoever. my guess is that the system is completely lacking between 100Hz and 200Hz.


OK, OK, so it has hardly any midbass. I do what I can to push my customers in the right direction, but if I were too pushy I'd probably loose the sale.

I determined early in my conversation with Joseph that he was somewhat of a bass-head. I asked about his music preferences, and he said he listens to "Tupac, and other stuff that goes BOOM!" lol. He was considering _keeping the factory speakers_, so I consider it a success that I at least steered him clear of that fatal error. Installing in the factory locations helped keep the cost down for him, so that's what it came to. There's a good chance we'll amp those in the future, I doubt he'd go much farther than that on this vehicle.

As for not knowing what midbass is, my own ride has four 6.5s (not amped right now, but I have a Kicker ZX200.4 just waiting to do the job) and puts out a decent punch in that range. His has some midbass, but I agree that it's not enough. His response is severely lacking from about 80 Hz to 120, but is mostly fine after that.


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## keep_hope_alive (Jan 4, 2009)

hehe. i'm just giving you a hard time man. good job getting him to upgrade over stock, i'm sure he's very happy.


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## TJ Mobile Audio (May 6, 2009)

No problem. Considering this is primarily an SQ forum, I should expect a little bit of criticism when I do (admittedly) silly things like this. While I'd love to make each car sound like a concert hall, installing for other people's tastes is essentially _acoustical prostitution_ and I just have to deal with that. I'll take what I can get, LOL!



keep_hope_alive said:


> hehe. i'm just giving you a hard time man. good job getting him to upgrade over stock, i'm sure he's very happy.


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