Options to send bass from trunk forward into Cabin?

[jjohan35]

Hi folks,

I'm going to install a sub in my trunk. You guys have any recommendations to deliver the sound from the trunk to the cabin? I looked at the backseat, it has a good layer of metal on the backside. I thought about removing rear fills, but I carry passengers on a regular basis. Any suggestions? Thanks.

[bikinpunk]

3 things:
1. Remove rear speakers so the pressure in the trunk can escape.
2. Deaden your trunk. That will keep the pressure from leaking out of your trunk or causing flex (which causes reduction in spl).
3. Put your subwoofer right up next to your trunk lid, facing the trunk lid if you can. This will help eliminate any wave cancellation since the backwaves and forward waves will be overlapping and "together" rather than separated and canceling each other.

[Englishe30]

Port your trunk perhaps

[2007SiSedan]

jjohan35, do you have a factory sub on the rear deck?

If so, remove the factory sub if you want high spl. No need to remove the rear fill speakers. If you are going for high SPL then I would recommend dynomatting the trunk. I have one 10" in mine and have no rattling. And I still have my factory sub in tact. Sounds extremely nice. The 10" gives enough rumble to fill the cabin and match the factory mids and highs.

In a sedan or coupe for that matter, I would only face the sub to the rear of the trunk. Allow a minimum of 6" in between the rear of the trunk and the face of the sub.

Another way of testing is to buy a small prefab enclosure with a single ten for $100 bucks as a test sub. Use that enclosure to test where you want to face the sub. In my sedan I got a cleaner response from facing the sub to the rear.

[bikinpunk]

Originally Posted by 2007SiSedan

In a sedan or coupe for that matter, I would only face the sub to the rear of the trunk. Allow a minimum of 6" in between the rear of the trunk and the face of the sub.

Do you mean Maximum? Otherwise, the further away from the trunk the subwoofer is, the more potential for cancelation there will be.

[2007SiSedan]

I have never seen a rear facing sub cancel in a Sedan or Coupe or Hatchback for that matter. Maybe I should rephrase that, if you are running a ported enclosure you want the port a minimum of 6" from the wall to maximize the port. Most peeps put the subs and port on the same plane.

[2007SiSedan]

http://www.clubknowledge.com/mr_b/2.htm

[2007SiSedan]

Originally Posted by DYohn the12volt.com

It is a physical fact that lower frequencies need to travel farther to acheive maximum SPL, so that moving a sub forward in the car and then facing it to the rear maximizes the cabin gain at lower frequencies. But do you have to do that? No. Put the woofers in your car and experiment. Move them around and see what sounds best.

[lush]

He drives an LX if I remember correctly.

Remove the rear fill speakers.

[bikinpunk]

A few things about that site:

I agree about the "rear fill" section. Unless you run 5.1 there's no reason to run rear speakers. Proper front-stage will trump all that ambient noise (I do mean noise) the rear speakers are playing.

Originally Posted by Mr. Brownstone

"Car audio stores jumped on the bandwagon and immediately sold you a speaker for every dip in your system, and a signal processor (eq) for every lump. An RTA was the best moneymaker in car audio since the 1F digital capacitor. We'll go there later. "

I agree.

Originally Posted by Mr. Brownstone

"Placing your subwoofer enclosure in the trunk of your vehicle facing the rear of the vehicle minimizes on cancellation. When 2 independent waves meet, they cancel or sum their amplitude depending upon what phase they are in."

This is what I'm talking about.

Originally Posted by Mr. Brownstone

Ideally, a flat response from 20Hz-20kHz would be desirable

Definately do not agree. An RTA is a useful tool to find out where your problem areas are in your car due to it's geometry, but leaving music with a flat response isn't "ideal". Ideal would be what the listener likes.

__________________________________________________ ______________




Back on topic, this is what I was referring to as for cancellation:


Here's a good drawing to understand how sound waves travel and what causes cancellation (these are assuming rear facing subwoofer):

This picture shows a subwoofer box positioned further away from the rear of the trunk


See how those reflected waves don't match up with the waves being put out by the subwoofer? This is an out-of-phase system, and kills response.

This is a more nominal response:


The two waves are now in sync, giving a more in-phase response.

I've actually tested various positions with a pink noise track and laptop based RTA on a 1/24th scale. Every car's different, but the same principle applies.

[jjohan35]

Yes I have an LX sedan. Thanks lush for the keen memory. I wish I could make my own hole in the rear deck.

I removed my rear fills when I had a two door celica back in the day since the backseats were pretty much non existent. But I'm driving passengers regularly with the Civic. I don't think removing rear fill is an option at this point. I have to carpool with employees.

I guess the discussion of subwoofer placement isn't that much an issue since I'm planning to get the custom fiberglass enclosure from audiosolutions due to space issues.

[4dr_bob]

I'm not finding this to be a big issue after all. With an SPL meter sitting on the center console, I measured a 6db increase at 40Hz with the passenger-side rear seat folded down. My sub has more than enough output to make up for this difference and I have a remote sub-level control up front (EX sedan with factory head unit).

[RPM]

Heres what was done to my Trunk and yes it is ported.

[lush]

You can take a air saw/dremel to your rear deck if you would like. It's thin, maleable metal for the most part. I've done it on many cars looking for the same option. Don't make it too big - it could flaw the frequency the port is tuned too.

[bikinpunk]

RPM, that's a clean install. Nice work.

Did you do it yourself or have a shop do it? I'd like to see process pics if you have them.

[RPM]

I had a good friend of mine do it for me he's done systems for me in the past in my other cars.we took out the spare tire out and used that space for storage so i can put my junk in my trunk haha..but ya all kidding aside its a clean install and it pounds hard and sounds very clean & crisp.

[LeezYy BabYy]

Instead of putting a sub in the trunk, get a shallow mount sub from a brand such as Pioneer or Kicker and putting it either in your backseat or under your seats.

[bikinpunk]

Originally Posted by LeezYy BabYy

Instead of putting a sub in the trunk, get a shallow mount sub from a brand such as Pioneer or Kicker and putting it either in your backseat or under your seats.

That's a good idea. With these type subs being easily available, it's at least worth checking into.