Venting subwoofer into cabin

 

New member
Username: 1stimer

Post Number: 4
Registered: Mar-05
Hello all. I visited the local car audio shop to get the installers reccomendation for my vehicle. I drive an old mercedes (300D), and the rear shelf is solid metal. Also, there is the problem of the gas tank blocking the bass. He reccomending building a vent system that would funnel the bass through the small opening that is in the rear shelf. He added that this would cost me $400 just for the enclosure and the vent system. Does anyone have any experience with a vent system to get bass into the cabin of a car. Any idea what this would entail. I am thinking of purchasing a idq-12 image dynamics sub and running it and some components with a decent 4channel amp. I just don't want to purchase anything until I know I can get the bass into the cabin from the trunk...if not I am going to be stuck with some sort of powered subwoofer on the rear shelf, or on the rear passenger floor. 1 more real quick....he also suggested mounting the tweets in the stock dash locations and the midbass on the doors. Any major problems with this idea? No room for kick panels. Thanks a lot to anyone who can offer some insight for me.
 

Silver Member
Username: Fishy

Tamarac Ft.Laud, FL USA

Post Number: 952
Registered: Sep-04
If he's talking about running the vent from a bandpass enclosure through the rear deck then that should work. I've heard a couple of those type of systems and they sounded pretty decent. Simply running the vents from a ported enclosure through the deck might not be as desirable however. The output above tuning(from the subs' cones) will still be attenuated by that gas tank, but that at tuning and below will be crankin. In other words you may get some serious output down low, but you'll probably have some pretty weak upper bass.

Hope that wasn't too confusing.

:-)

-Fishy
 

New member
Username: 1stimer

Post Number: 5
Registered: Mar-05
Thanks for the reply Fishy...so for the ported enclosure, I would need some good midbass drivers to compensate?

do you think this might work for my car?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=32823%26item%3D5767236034 %26%26
 

Silver Member
Username: Fishy

Tamarac Ft.Laud, FL USA

Post Number: 956
Registered: Sep-04
I dunno, It might be really difficult to get a fairly flat in-cabin response. I think you'd be better off with a bandpass or if the opening in your rear deck is sizeable just run a normal enclosure in your trunk and use that "vent" to help couple the air in the trunk with that in the cabin. If you've got some rear speaks and don't mind losing rear fill removing them would help out as well.

Another option would be running some free airs in your rear deck if your don't mnd cutting holes. You may not get the output or power handling you would using an enclosure, but with the right subs it would sound pretty good and you wouldn't lose any trunk space. Sounds like that trunk is pretty well sealed so thats an added plus for an infinite baffle/free air setup.

I always thought those bandpass setups ported through the rear deck were kind of nifty however.

:-)

-Fishy
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 3689
Registered: May-04
The best thing you could do if you want SQ, like said above, is to just cut a hole in the rear deck and let sound pass through that, instead of a bandpass port leading through there. If you wanted the flattest response you could get without EQ, your best option would be subs mounted in an aperiodic membrane, mounted on the rear deck. But you still won't get a razor flat response out of any car audio sub due to cabin gain.

As far as the components like that, it can work well if done correctly. Typically this works best with components that crossover in the 6khz region (rare to find components that do this), that way you are away from the critical vocal region and the sound won't be as layered, at higher frequencies the tweeters are more for presence than vocal reproduction. Also, higher order crossovers typically work best with off axis door installs, something like 18 or 24db/oct. You can also get even better results via time correction.
 

New member
Username: 1stimer

Post Number: 6
Registered: Mar-05
Trunk is amazingly sealed, but no room to mount free airs. I originally wanted to spend $600 for amp, sub and comp's, and try to do the install myself. Damn, this is starting to move beyond 1000 bucks...cant do it all right now...
ok...so if I decide to go the bandpass route....would some subs work better in that type of enclosure? Does $400 sound a bit pricey to design and build something like that? The sealed enclosure I was going to reluctantly try myself, but this undoubtedly will be well beyond my capabilities. Thanks for your time Fishy and anyone else who feels like chiming in.
 

New member
Username: 1stimer

Post Number: 7
Registered: Mar-05
Thanks Johnathan....I do not really want to start cutting, and I'm not sure if it is feasible...being the cheapskate that I am, though, that option may becoming more appealing if I could be sure that it would work. Thanks for the input on the components as well...the installer seemed confident that tweets in the dash would work just fine in my car, so I 95% sure I will go for that.
 

Silver Member
Username: Fishy

Tamarac Ft.Laud, FL USA

Post Number: 964
Registered: Sep-04
Not all bandpass boxes are created equal. Most are designed for high output and with a narrow passband(high Q)at a fairly high tuning frequency. Those can sound like @$$. You can also tune em pretty low with a lower Q but this usually results in a very large enclosure(or smaller subs), less output and reduced power handling. One of the first bandpass boxes I listened to(1989?) belonged to one of the Speaker Warehouse(JL Audio) guys. He had a pair of 8w2's firing into a common enclosure with a single port through the deck of his T-Bird. It played really low and sounded great, but could've used a lil upper bass help from some good midwoofers. I think he was only running 100 watts to each, but he was constantly replacing those subs, hehe.

If you can get a custom bandpass built, lower Q and tune, you might be really happy with the result, but it may take up most of your trunk if you want a good deal of output. Chances are you're still gonna need some really good midbass drivers up front as well.

-Fishy
 

New member
Username: 1stimer

Post Number: 8
Registered: Mar-05
Well, thanks...I guess the sub will have to put on hold until I decide what I am going to do. I will concentrate on finding a good 4-channel amp and some good components.
Looks like my sub choices are:
A) sealed w/holes cut into the shelf to allow bass to enter cabin.
B) free air sub using the trunk as the enclosure, or
c) Bandpass design custom built and installed

I know the decision is now mine---thanks for the input Fishy and Johnathan...I appreciate it.
« Previous Thread Next Thread »



Main Forums

Today's Posts

Forum Help

Follow Us