no one has mentioned a "aperiodic membrane" yet. unless that is too high end for any of you. when done 'properly' the will pound quite well. overcoming alot of the sub box problems that plague most cars. i have seen and heard 10" subs in a rear deck of a 1987 honda prelude. you couldnt even tell it was there. none of the system was visible. it was a complete stealth build.

you could always go with 8" subs as well. i had 3 JL 8" subs in a rather small enclosure in a HUGE trunk of my 1963 Buick LaSabre. at the time, i was only running 2 Rockford Fosgate PUNCH 60 amps. people thought i had 15's in the trunk. one amp ran the subs in mono -bridged mode, while the other one ran the 6x9's and 6.5' speakers . the deck ( hidden in the glove box) was a Premier M88.

your system IS possible, but as mentioned earlier, you may have to overcome some vehicle dynamics. i have personally experienced a "cancellation" in a Toyota Camry. system installed consisted of 2 PUNCH POWER 12" subs and a PUNCH POWER 250. box was correct and ported. system sounded GREAT until you close the trunk. cancelled all sub woofer sound waves. tried reversing the polarity of the subs, turning the box around to face the seat, trunk, checked phase of subs at the sub, checked phase at the amp from the deck, checked phase at the deck. nothing. changed to 2 POWER 10's. cured the problem. sound wave didnt cancel out and hit hard. customer happy. put the same box, same subs, same power in another car, hit hard enough to throw you into the front window.......so it wasnt the subs, or the enclosure...weirdest i have ever encountered in my pro audio life.

 

Dynaco used the concept ~40 years ago selling product at the consumer level. Admittedly, its application in an automotive situation wasn't terribly obvious to me, so I had to look it up. Forgive me, I don't understand how using a membrane to alter the Q of the system, decreasing its efficiency in the process (the last thing we need), is applicable to our situation.

 

this is true, yet sometimes you have to walk that fine line to get what you want out of the car without distroying it!!!

 

Let us know how the project works out. Really. If you can find a way to get defined, low-distortion bass into the car while it's moving without flexing its quarterpanels, hell, I'll be the first to copy your setup. No joke. I'll buy the same gear as you use and install it identically. It's just that every driver I've worked with in this car, ranging from 6.5 to ~16" ( a total IIRC of 14) and 7 enclosures representing a variety of aliments could never deliver such a thing without challenging the structural integrity of the car.

One can certainly minimize the burden on the electronics (and on the chassis) by rolling-off the bass rather steeply at ~50Hz, as the odds of it becoming louder than the LF emissions of this car are slim to none. This also does a lot to clean up the rest of the spectrum. We can also use a PEQ to kill some of the node-driven reinforcement; though, as you may know, feeding a node with power is acoustically futile. This fall into the "working with the car" category. Meaning, using its acoustics to gain an advantage. If you can come up with a better mousetrap, by all means.

FWIW, here's what I can tell you: 6.5" drivers in the rear deck, single 8" subs in the trunk (eg. ID8, eD, ARC) are essentially inaudible when the car is moving. Might as well not have anything there. Feeding them power results in mechanical noise that is audible, but not really desired. A single, fairly sensitive 12" driver like an IDQ12V2 in a properly configured enclosure can indeed overcome the noise component of the car with enough power behind it and some tuning, but there is a price to pay, as mentioned before. A high-excursion driver like a W7 that excels on the lower side of the spectrum will only be fighting the exhaust/drivetrain/road noise and not deliver enough definition where it can be audible. None if the drivers I used were chosen on a lark. Everything was modeled beforehand with this car's environment as a constant. Obviously, thing like panel flex and chassis integrity don't exactly fit into that algorithm.

What, exactly, is your plan of attack and how was it chosen? I'd like to learn something, too.

 

SPACE. its how it applies to the situation. he said he doesnt want to lose any space, asked about putting the subs (or woofers) in the rear deck, and i dont think it would decrease efficiancy if done correctly. it is loading the front side of the woofer, or the rear side. just like stuffing the box with dacron or lambs wool. it changes the Q just slightly. it also absorbs 'standing waves' and gives the sub a better 'sound'.

in the particular case of the Prelude, the front of the woofers were loaded and tuned and sounded great. the front stage of the system consisted of 8" woofers in the floorboard and under the dash were Image Dynamics HLCD(Horn loaded compression drivers).

 

Would you have a link we could look at? I honestly can't follow the explanation.

Standing waves inside the enclosure? Is that ever an issue, when using properly scaled dimensions? You can't mean the standing waves in the cabin, as it isn't possible to absorb the peaks driven by room nodes without physically treating the space and/or a PEQ. We're talking 16"x6' devices that look like columns flanking the Pantheon.

I've looked into ID horns for our application. Maybe one day I can put a little time into it.

 

i dont have a specific link, as the install was well over 15 years ago. however, i just googled a simple 'subs in rear deck' and came up with these.....it is similar to how the install was, but it was MUCH shallower. the system used B&W subs, Dynaudio 8'' mids in the floors, Image Dynamics HLCD with PRO drivers, Kimber Kable throughout the install, Alesis dual 32band eq(converted to 12v), two rockford 4 channel amps if i remember correctly. clean as can be. you wouldnt even know any of that was in this car. that was the thing back then to use the Alesis eq's converted to 12v. Audio Control really wasnt out then...and didnt hit the big time until later with there eq's.

standing waves arent really an issue, i concur, however, most dimensions are within 10% with the driver displacement. so by 'adding' dacron or lambswool it helps minimize loss-for top efficiency. its hard to explain, but i see you understand some of the dynamics.

the standing waves were inside the cabin of the camry infact. IF you opened the trunk, bass would hit hard and bring hell with it. we tried to replicate a civic that we built for a customer in this camry, and thats when the standing wave phenomenon occurred in this car. all of us installers check each others work-install, box dimensions, phase, everything. crossover points, etc. closed the trunk. its like we unplugged the subs. all rattle, and no bass. crack the trunk, whamo...bass in yo face......close it, the typical 'burrrrrburrrrbububrrr'. okay, hmmm lets try some dynamat everywhere....help a little with the rattles, but to no avail. we ended up changing the subs out for smaller 10'' power versions with rockfords enclosure recommendations again for these and it worked. customer happy.

i have had the Image Dynamics HLCD in my vehicle and loved them. i used their crossovers and their mids in the floor. i also used MONOLITHIC amplifiers at first when i competed. 100x2 for the front stage and 240x1 for the subs. sounded great. then i was sponsored by McIntosh with their MC431m (100x4) and really started placing at competitions. i went for sound Q versus SPL.

heres a couple more links to some pics....
HERE
and HERE

you get the idea and concept behind how it can be done if you work at it. however, as it was stated earlier,

how much bass does he really want??
silly bass??-the kind that makes little kids vomit when you roll by
or
enough to overcome vehicle frequencies and be great to listen to while cruising??



its all just money.......

 

just enough to overcome the vehicle and sound good while cruising. although after a long drive in it I'm almost deaf, just from the exhaust.

 

You know, it sounds like the point where the 12" box unloaded meshed perfectly with a standing wave inside the car. What are the chances of that?

For those interested, there's an easy way to calculate the nodes in the space, a frequency where the room, itself, provides reinforcement or cancellation: 565/ L/H/W of the cabin. Say the cabin is 10' long, 5' wide, and 4' high. The nodes (standing waves) would occur at 56.5Hz, 113Hz, and ~141Hz - ie. 565/10, 565/5, 565/4.

badhabit90, thank you for an interesting discussion.

 

the unloading of the box with the trunk closed was exactly what happened.

the owner of the stereo shop was rather upset we had to build another box for the car, but it all worked out. we sold the box to a chevy astro van owner. flipped the subs so they exposed the chrome magnets. he was happy ....


your politely welcome for the discussion. likewise sir. its good to hear 'some' people are still in the audiophile portion of it....

 

well i figured i would throw my 2cents in as well. yes, i have tried them and still currently running them. here is the set-up: Boston Acoustics Pro SE's in both the doors and rear deck, Boston Acoustics SPZ's in a custom armrest enclosure in the rear seat, and a JL 6 channel amp pushing all 3 component sets. granted the component sets were not cheap--i got really good deals on all of it and it more than makes up for especially since i am not compromising any trunk space with a sub or amp (amp is under the passenger seat). i have a little dynamat and dynalite in the doors and rear deck.

i would say it really depends on what you expect to get out of a system and what you are willing to invest in it.