Subwoofer addition to overpacked XJ (update) and new Q's

[Bones]

Well a while back I posted about wanting more bass in my sound system while adhering to the K.I.S.S. principle.

As usual with my “projects”, it seems that K.I.S.S. is out, and C.F. is in.

I now have a Kenwood 959 head unit; I am replacing my front pair of Infinity Ref 5002i speakers with an Infinity component 5000cs set up. I'll retain the rear 5002i's.

For my sub set up, I am in the process of designing a storage box for all my sh*t and I want to house the pair of Infinity Ref series 10" subs I just acquired (though I may decide to trim back to one sub and sell the other).

Power will be run by a pair of amps. The component amp will probably be a Rockford Fosgate 400.4 (RMS 50x4@4ohm) and I'm shooting for about 200W per on the subs (possible a second 400.4 bridged to two channels (RMS 200x2@4ohm)). I'm not set on the sub issue yet, ironic since it's what set this madness off in the first place.

For the audiophiles,

How sensitive are subs to space requirements in a sealed enclosure? The Infinity 1030w (10") subs call for .75 ft3 of space each. I am looking to place them in a sealed enclosure in the front of a custom 3/4" MDF or plywood storage box with drawers to the rear. How much room do I need to leave in front of the speakers (behind the rear seat) to keep the sound good (I notice my 8" sub on my computer only leaves about an inch under it for clearance, though it may be more of a bandpass set up).

I'm trying to keep this set up as stealth as possible, so nothing is set in stone yet. I may scrap the sub/storage issue and put one sub in the cubby with about 200-250W RMS if I can't make the box work on paper. I hope to have the measurements worked out for a weekend project.

Anything else I'm missing? I plan on putting the amps under the rear seat and cooling the space with small fans if needed.

I don't know much about this stuff so any advice is appreciated.

TIA,
Bones :skull1:

 

[Ramsey]

if your not set on the drawers, face the subs to the rear. they will be louder that way reverberating off the back, and just sound better too. make sure you give them the amount of air required. if you give to little it will take a whole lot more watts to get them to sound good.

 

[ladywolf]

bones....IM jeepin audiophile....he's a good source of info. i'm still trying to figure out where to mount my mp3 changer in my xj. it may end up going under the drivers side seat, but i'm not sure yet...might just pay to have it installed at home, i dont know yet. i'm not an electrical genius, tho since i have the same brand head unit and changer, it should be fairly straightfoward.

 

[bchulett]

Most SW's I've seen are ported... of course that's mostly for home theater systems. I believe ported enclosures are designed to assist the woofer to reach the lower frequency range ... movement of air, etc... and using less amps.

It's been awhile since I reseached and was up on all this, I believe if you seal a small enclosure the SW will be less efficient, requiring more amps to get to those lower frequencies---may result with distortion.

Speaker designs and the use of composite materials have dramatically changed over the years, so this basic theory may be obsolete.

Maybe if you seal the SW enclosure and port the XJ ? ... neighbors will love that.

 

[herreraxto]

mostly of the home sw are ported but because of the 8 ohms but on a car system most of the sw are 4 ohms and lower 4,2,1 ohms i have a little experince on this on my understanding if you want more room for your stuff a non ported sw is the perfect for you to get, because if is ported it needs to be more bigger to have a good soud quality and theres more distortion if is ported, or make the comparasion on a shop of car-audio installations or ask them about the difference

 

[collegeoffroad]

i know that the infinity ref. is a quality sub, but if you're willing to wait a bit, pioneer is coming out with a new sub which has a 4" mounting depth!

http://www.pioneerelectronics.com/pna/article/0,,2076_4057_104401920,00.html

 

[Jeep1XJ]

Make the speaker enclosure out of MDF, not plywood. MDF is better for quality sound. If you feel real good about it, coat the inside of your box with fiberglass to reduce reverberation with-in the box. A SEALED enclosure requires more WATTs from the amp to power the speaker, a sealed enclosure is better for good very low end quality sound. A ported box is more suited for in your face bass/thump. And a ported box usess less WATTS from your amp.
DO NOT MOUNT YOUR AMP UNDER THE REAR SEAT unless you do something to cool it off. I have an a/d/s amp and crossover module mounted under my rear seat---the Thermal safety's on the amp shut it off after 1 hour of continuos driving. I just prop up the back seat with a 2x4, if no one is back there and I'm fine. I too am working on a cooling set up for the amps. And if you go thru DEEP water crossings, make sure your floor is sealed GOOD.
This site refers to home speakers, but has good basic info. http://electronics.howstuffworks.com/speaker9.htm

 

[bchulett]

Most SW's I've seen are ported... of course that's mostly for home theater systems. I believe ported enclosures are designed to assist the woofer to reach the lower frequency range ... movement of air, etc... and using less amps.

It's been awhile since I reseached and was up on all this, I believe if you seal a small enclosure the SW will be less efficient, requiring more amps to get to those lower frequencies---may result with distortion.

Speaker designs and the use of composite materials have dramatically changed over the years, so this basic theory may be obsolete.

Maybe if you seal the SW enclosure and port the XJ ? ... neighbors will love that.

Correction: I meant watts ... not amps. LOL. Insomnia does wonders for the brain.

Thanks for the clarification regarding home theater vs. mobile audio.

 

[BennettXJ]

Im in the same situation youre in pretty much. got caught up in the sudio overkill after a few years. i plan on ditching my 2 alpine 12s in favor of one JL 12 and integrating it into my storage box as well. ive been drawing many plans for this and cant figure out the best way. right now my subs fire rearwards and are flanked by my OBA/storage container. i am gonna keep the OBA and try to work in the one sub, amp racks for the sub and components, and some storage space as well. theres barely enough room for a cooler now, and when im done i should have doubled the room. ill post pics (or plans, if im too lazy to get started soon) when i have them finalized.
-Ben

 

[Dirk Funk]

Hopefully I can help you out a bit:

A sealed enclosure, better known as an accoustic suspension, is ideal for your uses. Out of all the enclosures, it requires the least amount of enclosed volume to operate how you want it to.

You can design the enclosure with 10% less interior volume if you plan on adding accoustic dampening material such as accousta-stuff, blackhole-5, or some home insulations work as well. This effectively increases the enclosed volume.

If you decrese the amount of enclosed volume you will change the sound characteristics of the sub. If you were an audiophile you would shoot for the magic number .707 (Qtc) which reproduces sound most accurately. With less enclosed volume, the Qtc goes up and the sub starts to sound "boomy," but will "hit" harder. This is actually mechanically harsh on the driver and can physically bust your sub. Adding dampening material also lowers the Qtc.

MDF is denser than plywood which is why it is preferred by audiophiles over plywood. In the sub enclosures world, brute weight rules. 3/4 MDF is ideal.

Have you designed the eclosure? .75 cubic feet isn't too deep with a 10" sub, right?

As far as positioning goes: sound waves below around a couple hundred Hertz start to become omnidirectional, but what the sound waves hit after they leave the cone of the speaker directly effects how you hear the sound.

If you were to position the sub behind the back seat with the cone facing forward, you would effectively create a bandpass enclosure, with the seat acting as one of the slot-port walls. The catch is, no matter where the sub is in the jeep, this principle applies. This is why cars have an inherent 6 dB boost (louder bass) generally than home audio.

If the space you create in front of the cone is too narrow, with say a rectangular ratio of higher than 8 to 1, you can start to hear the sound waves, which move at the speed of sound, :idea: , and make a kind of wooshing sound, which sucks.

Audiophiles have told me before that nothing is quite as good as experimentation, which sucks and is just way too much work for a lazy kid like me.

Sorry for the long post; hope this helped out. I would be happy to try and answer any more questions.

 

[Tom R.]

Bones,

I'd listen to Jeep1XJ and Dirk, they know what they're talking about. Well said guys!

Just a few things to consider: I have a 10" sub in one of the wedge type sealed boxes. I placed it in various positions in the cargo area to "see" where it sounded best. The best place for this particular box is up against the back of the rear seat, in one corner, facing the rear hatch. I get deep, tight bass for such a small box. However, I need the room for other gear so I plan to install one in the cubby hole. XJEEPER installed his in the cubby and it sounds pretty good, not to mention it's out of the way and you don't need to tie it down, etc.

I hear very good things about the JL Audio subs that was already mentioned, and understand they work very well in smaller spaces/enclosures. I much prefer the sound of acoustic suspension (aka: sealed, infinite baffle, et al) over that of ported enclosures, but I'm of the audiophile clan, not the bassheads posse.

Tom

 

[JoeXJ]

A/D/S, good choice! I just happen to work for them. But I like to live by the "go big or go home" motto:

http://www.orioncaraudio.com/subwoofers/sub_H2_series.asp

Ya only need .33 Cubic feet if you feed it enough power

-Joe S.

Make the speaker enclosure out of MDF, not plywood. MDF is better for quality sound. If you feel real good about it, coat the inside of your box with fiberglass to reduce reverberation with-in the box. A SEALED enclosure requires more WATTs from the amp to power the speaker, a sealed enclosure is better for good very low end quality sound. A ported box is more suited for in your face bass/thump. And a ported box usess less WATTS from your amp.
DO NOT MOUNT YOUR AMP UNDER THE REAR SEAT unless you do something to cool it off. I have an a/d/s amp and crossover module mounted under my rear seat---the Thermal safety's on the amp shut it off after 1 hour of continuos driving. I just prop up the back seat with a 2x4, if no one is back there and I'm fine. I too am working on a cooling set up for the amps. And if you go thru DEEP water crossings, make sure your floor is sealed GOOD.
This site refers to home speakers, but has good basic info. http://electronics.howstuffworks.com/speaker9.htm

 

[Tom R.]

A/D/S, good choice! I just happen to work for them.

-Joe S.

That's awesome! I meant to make mention of A/D/S too, as I've been a fan of their home and car audio for many years. I finally bought my first pair of L570 bookshelf speakers 20 years ago and still have them today. Sadly, because of a lack of space I'm thinking about selling them.

So, what's it like working for this company? Do they give you good discounts or hand out "B" stock like candy?

Tom

 

[JoeXJ]

That's awesome! I meant to make mention of A/D/S too, as I've been a fan of their home and car audio for many years. I finally bought my first pair of L570 bookshelf speakers 20 years ago and still have them today. Sadly, because of a lack of space I'm thinking about selling them.

So, what's it like working for this company? Do they give you good discounts or hand out "B" stock like candy?

Tom

It's nice working for them ecpecially because its all owned by Directed Electronics which includes Orion, PPI, A/D/S as well as Viper car alarms and the 20 other brands of car video/security/remote start. Also a great brand to consider is Directed Audio, few people know it but Directed Audio amps hold the current world record for db!

www.directed.com start your drooling here.

-Joe S.

 

[Rawbrown]

I will attest to that... Joe finally got to hear my setup that, yes, he hooked me up with. I have a pair of studio 10's with dual voice coils at 4ohms ea. each voice coil is rated at 400 watts. powering them is the Directed audio 1100 watt class D amp stable to 1 ohm. while I can rattle the tint off windows of the honda sitting next to me. its not just bass. but the sound of a bassist finger pluck on the strings.

 

[JoeXJ]

Hehe just wait until I get my setup finalized for my RAM. 2 Orion H2 10" Dual Voice Coil woofers each powered by it's own 2400 watt directed amp. I have most the equipment but have yet to figure out how I will arrange it.

-Joe S (shattering windows in a neighborhood near you)

 

[Jeep1XJ]

Joe XJ I have a question for you in regards to the amp/crossover module i have.
I need the remote bass control for my set up. Right now there is a plug there with wires taped up, it sounds awesome! but doesnt look right.
My amp is the PH15 and the xover is the 642CSI. Also, any specson the set up. Can I get this INfo fron the A/d/s website?
Thx.

 

[JoeXJ]

Unfortunatly the remote bass control for that amp is no longer avaliable. A/D/S was bought out by directed several years ago and when it did we sold off all the b-stock and misc pieces to recoop looses and get a/d/s back on it's feet. I do have a detailed specs sheet for that amp and x-over. If you want it send me an email: [email protected]

-Joe S.

 

[ashmanjeepxj]

For the audiophiles,
How sensitive are subs to space requirements in a sealed enclosure? The Infinity 1030w (10") subs call for .75 ft3 of space each. I am looking to place them in a sealed enclosure in the front of a custom 3/4" MDF or plywood storage box with drawers to the rear. How much room do I need to leave in front of the speakers (behind the rear seat) to keep the sound good (I notice my 8" sub on my computer only leaves about an inch under it for clearance, though it may be more of a bandpass set up).

I'm trying to keep this set up as stealth as possible, so nothing is set in stone yet. I may scrap the sub/storage issue and put one sub in the cubby with about 200-250W RMS if I can't make the box work on paper. I hope to have the measurements worked out for a weekend project.

I didnt read the other reply's....

The recommended box size is only a recomendataion. The box size changes the "Q" of the speakers responce. Too small a box and your bass will sound too short, and uncontrolled. In a sealed box, you can never build one too big.
Build to what you have space for.

In addition to box size, the shape is important, Boxes that are wider then they are deep, typically sound better. A square cube is the worst box shape. Angles are good.

The mounting surface on the box is also important. If you mounted a speaker flush with a large wall that would be ideal, the sound would travel away from the wall very nicely. If you mounted a speaker into a snow cone shaped box, the sound would go forward, and some would go around the back of the box so you would loose alot of volume, or efficiency. For best efficency you would mount your speaker at the mounth of a mega phone (like mounting in a corner of a room 3 walls), it will be very loud but not sound as clean as if mounted against a flat wall (ideal).

Ive made afew of those side pannel sub boxes and they never sounded very good, it is a bad location, a bad mounting surface shape, but the box is typically wider then it is deep. But I have done it when I needed the space.

You wont be able to match the sound or efficiency of a good large sealed box mounted behind the back seat facing your hatch. Its optimal IMO.

10s are tiny.

 

[xjblue]

I'll add 2 cents to this thread, I don't know much about how it all works but the guys that have posted obviously do and posted great info.
I do have a decent setup simular to what you are looking for, a homebrew box with two 10"subs - stealth - and included storage area.

After my jeep was stolen 5 years ago, thieves had helped themselves to my tube woofer and deck(old used equipment, cost me $80) Got the XJ back and new sound became a priority. I picked up two older 100w 10" MTX blue thunders from my audiophile friend (well taken care of), I got a pioneer deck with great skip protection, and a planet audio 200w amp both display models so at a discount (not quite a hook up).

Then I enlisted the help of my friend and designed the box, he had experimental ideas on mounting the speakers, and helped me calculate the space needed, I added the cargo storage dimensions from there. finalized the plan then got some 3/4 MDF cut to spec and put it together.

I don't know if its considered ported or band pass so I'll just describe it, the 10"s face downward, with the rear spaces (top) fully enclosed and seperated for each speaker, The front space (bottom) is shared, and ported with a one inch slot port across the front of the box, speakers mounted flush with the front side of the front/rear devider. the front of the box sits behind the rear seat creating another space. the back of the box is my storage bin, I went with a simple lid for access rather than drawers so I can stuff it full as needed and controll vibration. Mounted the amp in the storage bin, room to add more amps in the future, my amp never gets warm on a hot day after a long trip playing tunes! A little unbolting, unplug the Amp and the box can be removed but hasn't been for a long time. gives me clean tight bass, puts it right in your lap, and matches the stock speakers well enough that upgrading the system further has been way low priority for now.

As for stealth it looks like a storage box, with the windows up and engine running you can't tell I've got subs in there, there is no advertising to potential thieves or shaking the neighborhood. The coolest part was when I discovered that a tool box I had laying around fit perfectly in the storage bin! Anyway, hope that gives some ideas.