Hummer H1: Subwoofer enclosure built in to aftermarket aluminum container seat bases- thoughts and opinions please?

[iansilv]

Vehicle : Hummer H1

Location in the vehicle: Subwoofers would each be inside seat base container under rear seats on each side of center tunnel

Space available (Length x Width x Height): 21" by 12" by 11", slightly irregular aluminum box structure as seen in the pictures.

Subwoofer make and model: Would like to use either an Alpine RS-W10D4 or a JL Audio subwoofer. For JL I would like the best option between the 10W7AE-3, 10W6v3-D4, 10TW3-D8, or a 10TW1-4. The structure of the enclosure dictates what I can use I think.

Subwoofer Size: 10"

Number of Subwoofers: 1 in each enclosure, one enclosure as the seat base under each seat.

Type of Port (Kerfed, Slot, Aero, etc.): sealed

What type of music do you like?: Rock, Rap, electronic, ACDC....

Is your goal SPL or Everyday Music?: Everyday music

Tuning Freq (Hz): as low as practical...

Volume : That depends on how the structure is designed inside the base I have attached pictures of...

Questions: So the seat base is an aftermarket enclosure product made to replace the seat bases in a hummer with this aluminum enclosed structure, assembled with rivets, and it is designed to fit the space completely. It has a volume of space in it and I want to have it welded, sealed, sound-treated to control reverberation and vibration, and then fitted with a subwoofer enclosure. This would give me 2 subwoofers in my Hummer H1, one beneath each rear seat. The truck is an open-top and I am in the process of sound-treating the entire body even though it is an open-top. It has hard doors as it is a civilian and I am putting an aftermarket top on it that is much quieter than the original was. The main issue is engine noise in to the cabin, which is where my focus will be with sound treating. Finishing things off, I will be wrapping it in black carpet to match the rest of the lower interior so. it as an OEM look to it like a modern vehicle, not the plasticky interior it was made with. I will be wrapping upper panels in leather.

My questions are as follows:

1. How precisely does internal volume need to be known and calculated for each sub if you know that the volume is comfortably above the manufacturer's recommended minimum and not large enough to be significantly above that measurement?

2. Are there any serious problems with building a subwoofer enclosure inside this aluminum seat base besides difficulty?

3. Of the subwoofers I listed, any one of them stand out as being good for this task?

4. I assume the enclosure would be built using mdf and/or fiberglass- I would love a fabricator's thoughts on how feasible my idea is. I know I do not have the skills to do this project, so I would like to know what to discuss/bring up with a fabricator I would have do these enclosures.

5. Would it be better to get a pre-made enclosure that comes with a subwoofer or even one that comes with an amplifier integrated as well?


Thank you for any and all thoughts on this project as I start to design and implement a full system here. I intend to have some speaker pods fabricated to hold minds and tweeters up on each side of each windshield pane, with the component woofers down near my feet, and rear three-way all-in-one speakers in the lower rear door panels I think.

Pictures below show the enclosure, its measurements, and the space It will go and some pictures of the existing install I am removing.

Click to read more...

 

[hispls 5,000+ posts]

Gross volume is around 1.5 cubic feet, I'd figure you're closer to 1 cube even after you figure in displacement of the woofer and whatever material you intend to use to turn those aluminum boxes into a rigid and airtight subwoofer cabinet. 1 cube isn't unreasonable for airspace for a 10" woofer sealed and overall sealed boxes are very forgiving as far as being off a bit in volume and still keeping close to "optimum" response.

Id say building up the walls with a few layers of fiberglass then using some MDF to make a baffle up top or in that side hole to mount the sub would be the best bet. Fiberglass materials isn't cheap and it's tedious work but I'm guessing you're not squeamish about spending money as this is not a cheap vehicle and you're coming out the gate thinking W7.

Really your big limiting factors here are going to be your vehicle. The position of those boxes in the vehicle are probably not going to be the best for acoustics and anything with a soft or semi-soft top is just not going to pressurize like a normal car. That said, even sky is the limit on what you're willing to do to get subwoofers in there you're coming off the line gimped by the vehicle.

I like kickpanels for installing mids and highs up front myself. Dash can be a bit iffy on whether or not it will work well. Most car audio branded speakers are designed to sound good off-axis (not aiming directly at you), so a really expensive component set if often the worst choice if you want to do that sort of mounting as the company who designed it built it around good response when mounted in or around the more usual factory locations. If mounting on-axis and up high first mock up some test boxes out of cardboard and put them up where you think you want them and make sure it doesn't interfere with your field of vision and you won't mind speaker pods up there then consider options buying components from Madisound or Parts Express... home theater type drivers will be designed for on-axis listening. Or if you're willing to buy some DSP option and do some tweaking you can probably use just about anything on or off-axis and brute force it with EQ and time alignment.

If this is all just a money is no object show car you may as well just take it to a shop that does high end custom fabrication go JL all around, their components are expensive but great sounding and high quality as is the W7 and their amps so you could keep aesthetics and at least rule out the equipment as the culprit if you're trying to chase down issues down the road.
Otherwise I'd have some other thoughts on gear, but I wouldn't be surprised if the custom install with full on deadening and custom fiberglass midrange/tweet pods + conversion of those aluminum things into boxes won't still be the larger share of your overall cost.

 

[iansilv]

Any thoughts on how to orient the subwoofers in the enclosure? Down-firing, up- firing, angled towards the front?

 

[1aespinoza 10+ year member]

Any thoughts on how to orient the subwoofers in the enclosure? Down-firing, up- firing, angled towards the front?

I would face the port and sub back. Even if you got a soft top, the rear gate will serve as a loading wall. I looked at the specs for the 10w6v3 and they only require 0.75 cu ft net for ported. I have heard they have better SQ than the 10w7.