# how to get loud in a 4 door sedan



## enerlevel (Jun 6, 2009)

i have already made a 6" hole in the rear deck. and the rear arm rest hole is alos through. are there anymore techniques by which i could make the setup sound louder in a sedan?

i have been using ported firing the trunk. could doing 4th order bandpass make it louder?


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## Oliver (Jun 25, 2007)

Serious subs should be all you need . . . DDAudio Digital Designs Speakers Made in the USA

amps of course too


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## TREETOP (Feb 11, 2009)

Yep a 4th order bandpass enclosure ported into the cabin will have a great chance of being louder, it will also keep your trunk lid vibrations down since all the output will be channeled into the cabin.


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## Oliver (Jun 25, 2007)

TreeTop for the win !! 

Noice suggestion !


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## TJ Mobile Audio (May 6, 2009)

I'm facing the same question. What about building a regular ported box designed so the port fires through the rear armrest opening? I have a customer who wants me to build one like that for his 4-door Audi, but I've never done it that way. Seems like it should work, but the cab will probably have a huge output hump near the tuning frequency (where the port does most of the work). I don't think he'll mind, he just wants it loud.

Any thoughts on building it this way? I could also do BP, but working with plexi is kind of a pain IMO.


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## enerlevel (Jun 6, 2009)

but is 4th order musical? the one i had last time could only play 2-3 songs really hard. and the rest of the songs were just crap.


with my ported box (2 x premier 3004spl 1000rms each) and (solid audio [email protected]) and my rear seat out , i can clearly hear a difference of about 2dbs which is like double the bass.


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## enerlevel (Jun 6, 2009)

i am sure facing the port through the rear arm rest wouldnt work. u will have to completely seal off the waves of either front or the back inorder to make it sound good. (basics of 4th order bandpass) but i might be wrong................


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## TJ Mobile Audio (May 6, 2009)

enerlevel said:


> i am sure facing the port through the rear arm rest wouldnt work. u will have to completely seal off the waves of either front or the back inorder to make it sound good. (basics of 4th order bandpass) but i might be wrong................


Was that to me? I was just saying _rather than_ a 4th order BP, why not a normal ported box, with the port firing through the rear seat? And if I were to build a 4th order, I'd have the subs sealed in one chamber, firing into a vented chamber, which would have a protruding port firing through the hole in the rear seat. Done this way, all of the output comes through the port, so there's no reason to worry about sealing up the trunk.


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## enerlevel (Jun 6, 2009)

i remember making a ported box with the subs facing the trunk and the port firing inside the car through the read ram rest. didnt work for me tho..... mayb i did somthing wrong dunno


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## timelord9 (Jun 4, 2008)

to TJMobileAudio + OP

have a read through these posts, the best way for max SPL and half decent SQ is a "mini-wall" through the ski hole. 

97 statesman big boot, 6 10 inch subs Good Question about porting - Mobile Electronics Australia

Sub box design using a pc program for MY Statesman. - Mobile Electronics Australia


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## TJ Mobile Audio (May 6, 2009)

timelord9 said:


> to TJMobileAudio + OP
> 
> have a read through these posts, the best way for max SPL and half decent SQ is a "mini-wall" through the ski hole.
> 
> ...


Can you post pics of this "mini-wall" technique? I read through the threads, but couldn't see the pictures because I'm not a member of that forum.

Thanks for the suggestion!


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## cubdenno (Nov 10, 2007)

Having the woofer firing into the trunk and the port firing into the passenger compartment begs for cancellation to occur due to reflections. There is an article online where a guy tried several placements of a sub enclosure in a vehicle with a trunk. If I get some time, I will try to find it. Work prohibits certain websites...

To get loud, run ported and lots of power. I have a single 15 in a trunk and hit 145 on tones 143 on music at the passenger windshield. And I think the car can sound very good. Because of transfer function the need to port sooooper low is silly unless you are truly in the pursuit of ultra SQ. 

I run both a ported enclosure tuned to 45 hertz and it gives a nice low pounding into the 20's and a single reflex bandpass that is tuned around 65 hertz that is ruler flat in car to 30 hertz. My bandpass is louder at certain points in the car depending on orientation. If the port is on the drivers side the passenger side is louder. and vice versa. Also if the port is facing toward the passenger compartment I lose a little efficiency but the sound is a little "tighter" musically. When I use the BP it is for overall efficiency across the usable bandwidth.

Just for the record, both enclosures are NOT used at the same time.


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## Patrick Bateman (Sep 11, 2006)

enerlevel said:


> i have already made a 6" hole in the rear deck. and the rear arm rest hole is alos through. are there anymore techniques by which i could make the setup sound louder in a sedan?
> 
> i have been using ported firing the trunk. could doing 4th order bandpass make it louder?


You cut a hole in your deck to make the bass louder?!
A 40hz sound wave is 28ft long. At low frequencies, the rear deck is all-but invisible. If it sounds louder, it's probably due to bass harmonics entering the cabin via that hole.

If you want it louder, do one or all of these:

- use a more efficient enclosure
- use more power


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## enerlevel (Jun 6, 2009)

wats miniwalling? any pics or any experience from anyone?

i am already using 1600rms and 2k rms subs. it sounds good for a dailt driver. but when i take off the rear seat completely , there is a significant increase in bass. isnt there any other way of acheiving it without taking off my rear seat all the time?


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## sqshoestring (Jun 19, 2007)

My IB baffle is behind the rear seat, I took the panel off the seat so all that is left is the cushion and wire frame. With the four 12s I can't tell if the seat is in or out. It will shake the car at 20-30Hz all day. But I have anther different car with fold down seats and small cheap single 10 in it, the bass doubles minimum when you open the trunk from in and outside the car. It has rear deck speakers into the trunk, factory, this small box only has ~100w on it with the factory system....so I have a better box/amp to try in it. So I see what you mean if you have that issue. I've moved the box around, it should be enough with the factory wimpy junk, but it does not work anywhere. And that car has a larger trunk than the first car. The first car I had various boxes with 10s and 12s and got good bass with any of them, or good as that particular box would do, and with the panel behind the seat installed.

Have to be really careful with BP boxes I've seen a few that did not work well, but I'm sure it can be done. I built a 10 BP a while back that worked great in the car long as mids would go low, but it was for my PC stereo. I modeled near flat 50-35Hz or something.


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## timelord9 (Jun 4, 2008)

slackers should just sign up... 

These are done by a guy called Phil de Groot in Queensland, Australia. used to be the DD distributor. If you need to know stuff about mini walling sedans, join up to mobile electronics australia and ask him


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## TXwrxWagon (Sep 26, 2008)

you could design the ported enclosure with the port outside the cabinet extending up to the rear deck through the hole you cut. just adjust your cabinet volume for the fact there is no longer the volume of the port being taken up inside. 

I would still try your best to isolate the entire trunk from the interior with a plate of some type behind the seat. If you need the access hole, make a removable panel for the rare occasion you need to use it.

also, if you are running any rear speakers, be sure to close them in so that the loaded sub wave in the trunk doesn't excite them with vibrations.

Rob


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## Salad Fingers (Jun 14, 2009)

To TJ Mobile Audio... I had a customer with a new Jetta that we did a 12W7 in a huge (like 2.5 cube) ported box with a Zapco C2K 9.0 on it. He is 18 and got used to it and wanted more, so we made a HUGE port in the rear deck and it helped with the bass not just being trapped in the trunk. Then he still wanted more, so we thought maybe sealing it off and firing one or two straight through the port we made would be even more intense. So we started experimenting and came to the conclusion that rear firing was the loudest by far. Firing into the cabin directly gave great sound and musicality, but the intense factor was compromised. So there's my two cents, hope it helps.


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## TJ Mobile Audio (May 6, 2009)

Salad Fingers said:


> To TJ Mobile Audio... I had a customer with a new Jetta that we did a 12W7 in a huge (like 2.5 cube) ported box with a Zapco C2K 9.0 on it. He is 18 and got used to it and wanted more, so we made a HUGE port in the rear deck and it helped with the bass not just being trapped in the trunk. Then he still wanted more, so we thought maybe sealing it off and firing one or two straight through the port we made would be even more intense. So we started experimenting and came to the conclusion that rear firing was the loudest by far. Firing into the cabin directly gave great sound and musicality, but the intense factor was compromised. So there's my two cents, hope it helps.


Thanks for the pointer, what car was that in? This customer's still raising cash so I've probably got a few weeks to figure out what we'll do.

When I saw that he had removed the arm-rest covering the ski hole, my mind started racing with ideas. I just always proceed with caution when trying out a new idea, I don't want to put my name on the line saying something will sound great, and then spoil my reputation when it doesn't, ya know?

I've got the sub and port in my box firing to the rear, and it's great for intensity. Pretty musical as well, in my opinion. As for my customer's Audi, to get loud I'll either need to build a bigger ported box with bigger ports and sturdy braces, or go for a 4th order BP ported into the cab. Either way, he'll need a much sturdier box, the one he has was built by a local shop and sadly enough is piss-poor quality. It flexes like Arnold Schwarzinegger when the bass hits, lol. _In this case that's not a good thing!_


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## Salad Fingers (Jun 14, 2009)

Hahaha Arnold, any reference to him is clutch funny for me. Anyways, it was in an '08 Jetta. We played with direction for hours with me, the fabricator and the custo in the car. Tried different songs, different types of music, I think I learned that the more distance between you and the sub, the better, and that in a car it will work with the pressure in the trunk to add intensity. Maybe I miswrote, I didn't mean to insinuate that rear firing wasn't musical. I just meant that in my experience when subs are firing directly into the rear deck that there is a certain degree of musicality and quality is gained. My old boss built a Mark 8 with 3 Zapco C2K amps, all F1 processing and speakers, and 2 W6 12's firing into the car like you are talking about. It was an amazing sounding car, but lacked intense bass. So I guess the best thing to do is just to qualify your custo!!!! It sounds like he just wants his head to throb, so my opinion would be stay simple, and fire at the rear. But make sure all the bass is breathing into the car very easily!!!! Hope I was of some help!


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## TJ Mobile Audio (May 6, 2009)

@ Salad Fingers:

Yeah dude, Arnold is da bomb! My friends and I used to collect funny quotes from his "Encyclopedia of Modern Bodybuilding" (the bodybuilder's bible) and laugh about them when we went to the gym. Our favorite was one about how the first time he did a serious work-out, he got so exhausted he fell off his bike on the way home!

I'd say you're right about my customer just wanting it loud. I set him up with a 740 watt RMS amplifier, and it was moving his subs to their safe limits, hitting very clean. He came back the next day and says "well I turned it all the way up, and it still sounds great"! I had a look at the amp, he had the level to max and the bass boost to max, and it pounded like hell. SQ was clearly not a concern, though, the clipping would drive me nuts! I told him he could blow the subs, but he didn't care. I guess I don't either, he bought them from someone else so I don't have to worry about warranty, lol. His next question (while my eardrums are still ringing) was "can I get any louder with the same equipment?"

Like I said, I checked out the box and it was flexing to the extreme, so I'll probably build him a new one. The chambers will be about 50% larger, and the ports will just have to be wide open and very long, as I refuse to tune the box any higher than the one he currently has. In fact, he mentioned having too much mid-bass so I'll probably drop the tuning a bit.

Also, I'm going to push him toward adequately damping his trunk, this made at least 3dB difference in my ride and I'm not even done yet! He's a high-school kid, I remember doing everything I could think of in HS to get my system louder, including running three 12s in a Sentra, but I didn't know the name of the game back then. While my tastes have refined a bit, and I don't go for pure SPL myself anymore, I can recognize a bass-head when I see one.

He told me the other day his goal is for me to build him the loudest system at his school. I smell competition in the air! That's it, the last nail in the coffin. If he goes through with the job, it's no holds barred! 1.5" MDF all around, 2.25" for the baffle, serious bracing on all walls, 5.0 CF net (for the pair of 12s), and two ports with a total area of 80 to 100 square inches. Tuning around 38 Hz. Of course I'll check it all out on software to make sure it works for his existing drivers, but like I said: no holds barred! If he can even afford that kind of treatment, lol. Maybe I can convince him to pour concrete in his doors to! J/K on that one.


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## TJ Mobile Audio (May 6, 2009)

To the OP:

If you feel like making holes in the rear deck makes your bass louder, I'm assuming you've already removed your rear deck speakers? That should help, too. It really shouldn't make that much of a difference, but if you say you heard a difference, I won't argue with you. As noted earlier, bass frequencies can have wavelengths longer than your entire car, so a 6" hole in theory won't do much. That being said, I have no speakers in my rear deck, but it's just because they didn't sound good there.

I'll tell you what I'd tell a customer: if you haven't already, damp the trunk, you won't be disappointed. I've seen huge gains on multiple vehicles by carefully damping the trunk. It's not free, but is costs less than an extra subwoofer!

If you're going for the hatchback effect, and if your rear deck is large enough – you've already demonstrated that you don't mind hacking it up – you could consider mounting the subs in the rear deck. When I do this, I go with a pretty thick baffle, usually 1" or 1.5", and seal off the trunk. Depending on how well your subs handle IB, you might have to build an enclosure underneath. Then again, I'm not sure if you can even fit the subs in the rear deck with your particular car. Just another option to explore.


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## Salad Fingers (Jun 14, 2009)

Hahaha, I've dealt with this kid a million times. If he is wanting to stay with the same equipment, then the only thing you can do for him is the proper box and deaden the trunk. I would tell him that it is going to be noticeably louder, but if he wants to blow the roof off he needs bigger amp, better subs... etc. Well actually, what is he using? You are definitely on the right track with trying to maximize the output of the stuff he has. Although, something I learned from a veteran with some world titles under his belt at the last shop i worked at... tune it lower. Ported box will play everything above the tuning frequency, and NOTHING below it. We always tuned them @ 28-33 or 34 hz. Really low, but it always turned out awesome. Obviously consult the recommendations for the sub, but that seemed to work out good for us.


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## HIS4 (Oct 6, 2005)

enerlevel said:


> but is 4th order musical? the one i had last time could only play 2-3 songs really hard. and the rest of the songs were just crap.
> 
> 
> with my ported box (2 x premier 3004spl 1000rms each) and (solid audio [email protected]) and my rear seat out , i can clearly hear a difference of about 2dbs which is like double the bass.


2dB is not double the output. 3dB is double the power but it is not heard as double the output by the human ear. To hear double the output you're looking at about 10dB. 1dB is typically the lowest increment that can be detected by the human ear.

How loud are you trying to get? Is this for SPL competition? I had a DD 9510 running off a TRU Hammer at 1 ohm (1500W) in my Audi S4 and it was way louder than you could stand to be in the car. It was in a ported box but I didn't do anything like cutting holes in the rear deck. I think you've either maxed out what you're current equipment can provide and need to improve somewhere or you need to redesign your enclosure as others have suggested.


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## TJ Mobile Audio (May 6, 2009)

Salad Fingers said:


> Hahaha, I've dealt with this kid a million times. If he is wanting to stay with the same equipment, then the only thing you can do for him is the proper box and deaden the trunk. I would tell him that it is going to be noticeably louder, but if he wants to blow the roof off he needs bigger amp, better subs... etc. Well actually, what is he using? You are definitely on the right track with trying to maximize the output of the stuff he has. Although, something I learned from a veteran with some world titles under his belt at the last shop i worked at... tune it lower. Ported box will play everything above the tuning frequency, and NOTHING below it. We always tuned them @ 28-33 or 34 hz. Really low, but it always turned out awesome. Obviously consult the recommendations for the sub, but that seemed to work out good for us.


Hmm, this guy would like most of my builds then. Generally I tune between 25 and 32 Hz, I guess I'm saying 38 for this one because his current box is tuned around 45 Hz, if my ears weren't lying to me.  Low tuning works best on large boxes in my experience, but I'll run the parameters and see what I come up with.

As for equipment, he's got some decent Planet Audio 12s and a _massive_ 1600 watt amp by SPL. The amp is one I sent in for refurbishing a while back and then sold to him, it is a real champ. 22" long and not much wasted space inside. I'd say the equipment is quite adequate, but I'll let him lay out the budget and we'll go from there. I'll maybe spec a box that I also know will work for more serious subs _just in case_ he wants to upgrade...


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## Salad Fingers (Jun 14, 2009)

yes, plan ahead. very good idea!


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## TJ Mobile Audio (May 6, 2009)

Salad Fingers said:


> yes, plan ahead. very good idea!


Yeah, I hope it doesn't sound sleazy, it gives me the chance to make another sale in the future _and_ saves him the money of having the enclosure rebuilt (again). Sounds like win-win to me!


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## Salad Fingers (Jun 14, 2009)

Absolutely!!!! Make that money!!!!!


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## enerlevel (Jun 6, 2009)

my car is a 4 door civic . i have about 70A main battery and another 70Ah in the trunk along with a 2 farad cap. 

my equipments are

pioneer p80rs

kenwood 6.5 components door.

alpine f405 amp


i was actually planning to put 2 soundstream 12"splx at .5 ohms on a lanzar optidrive 2000D . 
so was looking for the max sound from them. i have heard splx are some tough a$$ subs. i might be wrong tho. 
its a daily driver and not a spl/competition car. but yes i do want to go loud. 

removing the rear arm rest makes ALOT of difference. removing the rear seat makes it even more. so mayb removing the whole rear deck( the metal sheet on top where we place 6x9s) would make it sound louder? but is it safe to remove the whole metal body? since alot of the trunk rods and clips are held on tht metal sheet.


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## cubdenno (Nov 10, 2007)

TJ Mobile Audio said:


> Hmm, this guy would like most of my builds then. Generally I tune between 25 and 32 Hz, I guess I'm saying 38 for this one because his current box is tuned around 45 Hz, if my ears weren't lying to me.  Low tuning works best on large boxes in my experience, but I'll run the parameters and see what I come up with.
> 
> As for equipment, he's got some decent Planet Audio 12s and a _massive_ 1600 watt amp by SPL. The amp is one I sent in for refurbishing a while back and then sold to him, it is a real champ. 22" long and not much wasted space inside. I'd say the equipment is quite adequate, but I'll let him lay out the budget and we'll go from there. I'll maybe spec a box that I also know will work for more serious subs _just in case_ he wants to upgrade...





Salad Fingers said:


> Hahaha, I've dealt with this kid a million times. If he is wanting to stay with the same equipment, then the only thing you can do for him is the proper box and deaden the trunk. I would tell him that it is going to be noticeably louder, but if he wants to blow the roof off he needs bigger amp, better subs... etc. Well actually, what is he using? You are definitely on the right track with trying to maximize the output of the stuff he has. Although, something I learned from a veteran with some world titles under his belt at the last shop i worked at... tune it lower. Ported box will play everything above the tuning frequency, and NOTHING below it. We always tuned them @ 28-33 or 34 hz. Really low, but it always turned out awesome. Obviously consult the recommendations for the sub, but that seemed to work out good for us.


The thing is, with transfer function porting low is not necessary. The woofer will play below the tuning frequency. the woofer just has zero control and you can seriously reach the mechanical limits in a real hurry.

You can port in the mid 40's and still hit the upper 20's in car. Most music is above 30 hertz. To get those ultral low frequencies you are looking at movies or as a rule specialized recordings. Things from Sheffield Labs Telarc etc...

I am willing to bet medium money that if you take same woofer and working enclosure volume, and tune it at 45 and 30 hertz, the 45 will play louder in car over most of the frequencies than the 30 hertz box. I have run into this with my sub as well as others. I have no guarantee that this will happen on all subs. but even playing with programs like WinISD, it show the occurrence more often than not when I have played around.


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## TJ Mobile Audio (May 6, 2009)

cubdenno said:


> The thing is, with transfer function porting low is not necessary. The woofer will play below the tuning frequency. the woofer just has zero control and you can seriously reach the mechanical limits in a real hurry.
> 
> You can port in the mid 40's and still hit the upper 20's in car. Most music is above 30 hertz. To get those ultral low frequencies you are looking at movies or as a rule specialized recordings. Things from Sheffield Labs Telarc etc...
> 
> I am willing to bet medium money that if you take same woofer and working enclosure volume, and tune it at 45 and 30 hertz, the 45 will play louder in car over most of the frequencies than the 30 hertz box. I have run into this with my sub as well as others. I have no guarantee that this will happen on all subs. but even playing with programs like WinISD, it show the occurrence more often than not when I have played around.


What, you don't watch movies in your car? I've got my share of Telarc CDs as well, I even use them occasionally when demoing my system!

You know, I mostly agree with you. Given that cabin gain is a real thing, the lowest of the lows should still be heard even with high tuning. Nonetheless, I'm tired of hearing systems that are all "top heavy" and have extreme output from 50 to 80 Hz, with next to nothing below 40 Hz. The local shops build smallish ported boxes tuned around 45 Hz, and that sort of "one-size fits all" approach does not float with me.

Another reason I tune low is to decrease excursion in the crucial "voice-coil smashing range", as opposed to just letting the woofer unload. Not all amps have infrasonic filters, and not all customers care to pay for amps that do. Low tuning can protect the equipment to an extent, IMO.

Like I said, I plan to aim for 38 Hz tuning for this guy. By my standards, that's pretty high & I bet it will get loud. The ports will also be quite large, and the box will be a beast as well. The amp he has has no infrasonic filter, or I'd tune a bit higher. Most of my customers have an SQ lean and I've found low tuning helps for that; this guy thinks claims he likes SQ but has demonstrated he's all about loud.


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