i just got a 94 accord and my subs seem to be muffled by the back seat i get very little sound from them i know the subs sound awsome i have the exact same setup as i had in my 91 eclipse and i could feel the bass in my chest but for some reason the trunk is just killing all my sound and suggestions?

i have 2 12 inch lanzar optidrives and a 2400 watt elemental design amp and a jvc touch screen mp3 player deck

 

remove the rear speakers. those large holes let a lot of bass through, and you don't need them anyway.

have you verified the subs are not miswired? how are the subs facing? where is the amp grounded? what is the measured voltage at the amp terminals with the system running, car on?

have you replaced the front speakers? if you choose to remove the rear speakers for more bass, you'll need good front speakers so you can hear music.

 

the subs r facing to the rear they r wired correctly i wired them myself and double checked them i will have to try taking out the speakers in the rear deck i would have to replace the front door speakers but i will try it without the back ones first b4 i go threw the hassle of buying new ones. the amp is grounded to the body where the spare tire is located and the amp is getting 12 volts

 

you should have 14V when the car is running, system on.

but yea, the bass needs a path into the cabin. if the rear seat is not an option, the rear deck is easy.

i had a 1990 Chrysler 5th Ave, it had a solid sheet of metal behind the rear seat, and a spare tire. i relocated the spare tire, and cut a rectangular hole that lined up with the rear seat arm rest. the arm rest folded down, but there was fabric behind it. i removed that and carpeted the metal. the end result looked like the car came that way. it was pretty cool. i don't know if you have the same option.

if you share pics of the back seat from inside the trunk we may have other ideas.

i don't run rear speakers, haven't for several years. i put all of my power, money, and time in my front speakers, and i'm 100x happier.

 

You don't need any sort of hole to let the bass through. Subwoofers can be places in a sealed enclosure for a reason and will create more bass when in a sealed trunk. Play a song with alot of bass then get out and open the trunk and you'll notice the bass decreases.

Next, the subwoofers are from ebay and JVC doesn't make the best headunits. I've never even heard of the amp brand. So, you really should estimate the amp RMS output as 1/4th of what is says and same for the subs. Also, one sub IS louder than two. I had two 12's and over the summer I cut my box in half and now have only one.

To me it seems like something isn't wired up right or you've blown the coils in those cheap subs.

 

http://www.edesignaudio.com/product_...products_id=44

I assume this is his amp.

Elemental Designs makes ok stuff. Sure, the 2400W is max, but it is probably a fine match for the overrated subs. Lanzar subs aren't the greatest either, but they move air just like any other sub. He could do much worse, and he was happy before. No need to spend a grand replacing working gear (if he even has the cash flow).

The main problem is going from a hatchback (ideal) to a trunk (not ideal). The hatchback gave you loading off the rear glass, is a smaller overall volume, and there was nothing between you and the subs. Now you have reduced loading, cancellation, and they are choked off by the seat and rear deck.

If you take a look at rear deck speakers (turned off) when subs are playing, the cones move due to the pressure of the trunk. they (rear deck speakers) restrict the pressurization of the cabin. remove them and you will notice air moving through the openings. crazy, eh? it's an easy thing to prove to yourself. cars with rear seats that fold down are easy to test as well. seat down always results in more bass (higher SPL) than seat up. cars that don't are suffering from cancellation (explained below).

essentially, what you're doing is creating pressure waves that are trying to reach your ears. the more stuff you do to block that (like sealing the trunk), and cancel the original wave (phase interference), the worse performance you have. a completely sealed trunk is a worse performing example since any pressure must fight through materials to get in the cabin.

it was mentioned that opening the trunk and bass gets worse, as an example of why your trunk should be sealed. however, that is not accurate. in some cases, opening the trunk improves bass in the cabin because it reduces/eliminates destructive interference caused by out of phase waves. a lot of people will notice this, and i am asked about it a lot (questions like "why is my bass louder when my trunk is open?"). poor orientation of the sub box results in phase interference and cancellation. the quarter wavelength of 60Hz is 4.68 feet. so if your sub box is 4.68 feet from the rear of your trunk, the reflected wave will cause cancellation. some frequencies are partially canceled, some added. that is why rear facing subs in a trunk are boomy, unnatural, and lack overall SQ, and can sound better when the trunk is open (eliminates cancellation). just facing a box forward (without sealing around it) usually performs worse because of cancellation and no loading. make sense?

a trunk should be closed and performance should be improved, not because the trunk is sealed, but because reflections from the trunk lid should reinforce the bass. however, you want that pressure inside the cabin where you sit. essentially you're arguing for a bandpass box with no vent. a sub in a sealed chamber firing into a sealed chamber. that doesn't work well outside those chambers.

installation is 90% of a good sounding system. the performance of subwoofers is dominated by their installation. instead of investing money on expensive gear that will perform about the same, i recommend changing how what you have now is situated in the vehicle. once you get your existing gear sounding good, anything better can be fully enjoyed.

the best performing sub installations (SQ and SPL) have the driver cones INSIDE the cabin with little to no cancellation. hatchbacks, SUV's, vans, etc. can all benefit from rear loading and no blockage. sedans are the trickiest and usually require some form of modification. ideally, you'd reinforce the rear deck and mount the drivers there instead - giving you hatchback performance in your sedan. course, that is A LOT of work.

this isn't a personal attack. consider it point/counterpoint.

edit: fixed my use of the word "you", now it's general. Cheers!

 

well i have tried it with the seat down and it sounds pretty good but not as good as it did in the eclipse but i understand the hatch back versus the sedan i get that but the subs are not name brand but they r competition subs i payed alot of money for these subs i sell them and the easily hit 140 db which they do in the accord with the seat down and as for the jvc head unit its way over rated i dont care for it the amp is a half *** amp but it does very good i just lose the sound with the seat up and i have kids so the seat has to stay closed so i was just wanting a way to get the bass back when the seat is up. and i also sell the lanzar brand in my store not all of them are the greatest but some of them are actually really good not kicker obviously but better than sony , jvc , jensen stuff like that nothing compares to kicker or jl

 

i've known people to remove the hard backing to the rear seats, to open them up more, acoustically. the cloth of the rear seats won't do much to affect bass, the foam does, and the hard backing certainly does.

one option may be to modify the rear seats to allow the passage of air. if air can get through, so can bass, since sound is the propagation of pressure - which is the movement of "air" molecules, we want to facilitate the movement of air. i say "air" since sound can propagate through any material, (i.e. water, steel, etc.) and the speed changes, but in this case we're dealing with air. they would look the same inside the cabin, but would maybe have less foam in the center and would not have a hard backing (though you could use open weave carpet or grill cloth for cosmetic covering).

granted, the wavelengths associated with your subs are long, long enough that they are allowed to travel through the seat, through the metal, glass, etc. and we can clearly hear that inside our homes, through our walls, etc.

i closely study the transmission loss through various materials. i know that the lowest octaves are the least effected by lightweight materials. but experience teaches me that putting subs in a trunk without openings to the cabin will result in a reduction in output. fold down the rear seat = more bass. open up the rear deck = more bass. and my professional experience teaches me that any crack or opening will allow sound to escape, especially low frequencies. the best way to attenuate sound is to create an air tight seal between the space of concern. if you don't want to attenuate sound - remove the blockage.

i hope some of this has been helpful. seeing as how you are not the only person with that car and that issue, please let us know what your further testing yields, and what your end decision is.

 

Great Information your giving out..my instincts tell me you seem to be a Master Stereo Installer of sorts...am I right?

WheelBrokerAng

 

thanks for the complement Ang. I'm an Acoustics Engineer (working primarily with Architectural Acoustics - designing concert halls or abating unwanted noise). I have an Electrical Engineering degree (analog and digital circuit design and power systems) and 15 years experience with home/car audio video installation (some professional, most individual). I've learned a lot over the years, and continue to learn more every day both in my career and my hobbies. Installation doesn't pay as well as engineering, so I install as a hobby. if I had my way I'd work for an audio company designing equipment (and maybe will some day).

I believe that theory helps us understand why/how practical application works. The best thing to do is experiment, because predicting actual results is time consuming. As things become non-linear, the math gets very interesting.

If anyone is interested in an introduction into Acoustics, I recommend a short read of Indiana University's Acoustics Primer -
http://www.indiana.edu/~emusic/etext...r1_intro.shtml

It won't make you an Acoustician overnight, but it will introduce to you basic theory and terminology (you will certainly learn something).