The Proper Subwoofer Enclosure For A Gs Trunk|no Trunk Rattle *video*&

[SHiZNiLTi]

(2) RE Audio 10" SX's in a 4th order bandpass ported through the rear deck of my Lexus GS300 with a 6" Aero Port powered by a Hifonic BXi-2010D on a Kinetik HC2400 in the rear and a red top Optima up front, 1/0 gauge Kicker power cable, Big 3 electrical upgrade.

1.6cuft for sealed section

2.3cuft for ported section

Due to the nature of the 4th order design even with the tuning of the ported section being 45hz this setup hits the lows like crazy and peaks at around 32hz. I designed the box to have a 28hz-65hz passband with +3db boost.

The bass is super smooth and very very deep, it's the smoothest and best sounding bass I've heard!

Having this type of bass with absolutly no trunk rattle is awesome, 4th order's ported through the rear deck with a precision aero port FTW!!!

The sun reflection makes it look like a sound wave on a oscilloscope...

[SHiZNiLTi]

The tape on the box, it's just temp. The trunk is unfinished.... Haven't had time to make a flush cover for it yet. The cover will strech across the entire length of the box, it will be carpeted in the same color as the trunk carpet and hide the box and the gaps to the left and right of it. I also plan to make a false floor for the amp to flush mount it under plexiglass with a couple 80mm pc fans for cooling. I might flush mount the batter but it would require me to remove my spare tire. With the amp flush I can throw the Lexus rug over it and you wouldn't see a system in my trunk, it would just look like a smaller stock trunk.

[nc211]

Dude, I must say, that is one impressive set up. I'm not into the big ole' stereo systems anymore, and when I was a teenager driving around with my dad's house speakers hooked up to my sparks n' static 9,000 watt ($49) amp, in my VW Golf, I thought I was the man. Bumpin' to some Ice Ice Baby. But, you've got me beat, by a mile.

I will offer one element of caution though, actually two. 1) no matter how good the car looks, rattles are rattles and I'm willing to bet you're gonna develop a few. And 2) for the sake of humanity, turn it down when you're at a stop light! I was at a light the other day with my son in the back, and some kid pulled up next to us with his system blaring, and scared my son so badly he wouldn't stop crying. We got to the next stop light, he was still next to us, and I rolled down my window to tell him that I was an off-duty cop, grabbed his tag number already, and was going to issue him a citiation for noise pollution if he didn't "turn that G/D Sh*t Down". He, being all of probably 16 years old, driving a new BMW from mom and dad, was too stupid to realize that most cops in Illinois, don't have North Carolina license plates, and turned it down and appologized. Then proceeded to take the next right turn to get away from me. So, please, just be aware of your surrounding when jammin' with that monster system. I don't think I have ever seen a set up actually flex the sheet metal of a car's roof before! That, is, impressive! I said, THAT IS IMPRESSIVE! What, are you deaf? ;)

[SHiZNiLTi]

Dude, I must say, that is one impressive set up. I'm not into the big ole' stereo systems anymore, and when I was a teenager driving around with my dad's house speakers hooked up to my sparks n' static 9,000 watt ($49) amp, in my VW Golf, I thought I was the man. Bumpin' to some Ice Ice Baby. But, you've got me beat, by a mile.

I will offer one element of caution though, actually two. 1) no matter how good the car looks, rattles are rattles and I'm willing to bet you're gonna develop a few. And 2) for the sake of humanity, turn it down when you're at a stop light! I was at a light the other day with my son in the back, and some kid pulled up next to us with his system blaring, and scared my son so badly he wouldn't stop crying. We got to the next stop light, he was still next to us, and I rolled down my window to tell him that I was an off-duty cop, grabbed his tag number already, and was going to issue him a citiation for noise pollution if he didn't "turn that G/D Sh*t Down". He, being all of probably 16 years old, driving a new BMW from mom and dad, was too stupid to realize that most cops in Illinois, don't have North Carolina license plates, and turned it down and appologized. Then proceeded to take the next right turn to get away from me. So, please, just be aware of your surrounding when jammin' with that monster system.

Haha funny story about your old school setup bumpin vanilla ice :P

Ya I totally hear ya about bumpin it at a stop light being disrespectful to others. That's why I really like the 4th order design, it keeps all the bass in the car and doesnt leak out the trunk this way I can play my music at a medium loud volume without trunk rattle anopying noise. Nothing worse then hearing horrid trunk rattle !Removed! sounds at a stop light. I feel like yelling at those aholes and tell them that they arnt impressing anyone with that crap rattle of a system they have and then blast them with a 30hz tone :P making them feel like crap :D

Thanks for the comment. It took a long time with alot of number crunching to design the 4th order enclosure properly so I'd get the perfect blend of sound quality and output for all types of music...

To use the following calculations, you will need to know the following:

Vas = equivalent air compliance for the driver (litres)

Fs = driver resonance frequency

Qts = driver Q at Fs

The following equations will allow you to design a 4th order bandpass system with a desired low frequency limit or a desired gain. You will need to choose a value for "S" that suits your requirements. 4th order bandpass systems where S is less than 0.7 will have a degraded transient response, but wider bandwidth and smaller box requirements.

if S = 0.7, then b = 0.7206, passband ripple = 0.00 dB

if S = 0.6, then b = 0.9560, passband ripple = 0.35 dB

if S = 0.5, then b = 1.2712, passband ripple = 1.25 dB

4th order bandpass system with desired low frequency limit

Choose a value for Fl, the lower 3dB cutoff frequency,

then,

Fl' = (Fl*Qts)/Fs

Fh = (Fl'+B)*Fs/Qts

Qbp = (Fl'*(Fl'+B))^0.5

Fb = Qbp*Fs/Qts

Vf = (2*S*Qts)^2*Vas

Vr = Vas/((Qbp/Qts)^2-1)

Pa = -40*LOG(1/(Qbp*2*S))

where,

Fh = upper -3dB cutoff frequency (Hz)

Qbp = Qtc of sealed chamber

Fb = resonance frequency of vented chamber(Hz)

Vf = net volume of vented chamber (litres)

Vr = net volume of sealed chamber (litres)

Pa = gain (dB)

4th order bandpass system with desired gain

Choose a value for Pa, the gain in efficiency,

then,

Qbp = ((10^(-Pa/40))*2*S)^-1

Fl = ((-b+(b^2+4*Qbp^2)^0.5)/2)*(Fs/Qts)

Fh = Fl+(b*Fs/Qts)

Fb = Qbp*Fs/Qts

Vf = (2*S*Qts)^2*Vas

Vr = Vas/((Qbp/Qts)^2-1)

where,

Fl = lower -3dB cutoff frequency (Hz)

Fh = upper -3dB cutoff frequency (Hz)

Qbp = Qtc of sealed chamber

Fb = tuning frequency of vented chamber (Hz)

Vf = net volume of vented chamber (litres)

Vr = net volume of sealed chamber (litres)

Pa = gain (dB)

I don't think I have ever seen a set up actually flex the sheet metal of a car's roof before! That, is, impressive! I said, THAT IS IMPRESSIVE! What, are you deaf? ;)

Even at low volumes this flex is noticable, it's not a vibration though its just the air pressure in the cab changing due to the high excursion (XMAX) of the woofers. With the 6" aerport having flared ends to it there is no port noise when air passes from out of the box through the factory subwoofer cutout hole into the cab of the car, this makes for a smooth deep sound that on some subsonic frequencies you wont even hear the bass, but just feel it or see it moving your shirt.

To see your own roof flex crack your sunroof, kepp all other windows up. Open a door then slam shut semi hard and you will see your roof flex from the air pressure change.

[nc211]

With all of that air moving into the car, what happens if you've got the windows up and roof closed? Are you at risk of shattering a window by "pressurizing" the cabin? Kind of like overfilling a balloon?

It's not the rattles of the trunk that really bother folks, as much as the "boom booom boooooom" coming from the car next to, rattling your teeth loose. Back in my day, and you Kansas City "Overland Park" folks on here will know what I'm talking about, the "show" was at the KenTacoHut on 119th & Metcalf. You weren't cool, if you weren't "2ligit2quit".

You know what, screw it. Jam that sucker man! God, I'm getting old when I'm telling kids to "turn that damn thing down". I already yell at them for driving through the neighborhood too fast. That's what happens when you've had your fair share of bar fights, the clippers get quiet when she's cutting the hair on top of your head, and you get the joke "my 201k."

You oughta' send that math equation to AIG, they could use some "bumpin' ya' !Removed!" results.

[SHiZNiLTi]

With all of that air moving into the car, what happens if you've got the windows up and roof closed? Are you at risk of shattering a window by "pressurizing" the cabin? Kind of like overfilling a balloon?

You oughta' send that math equation to AIG, they could use some "positive" results.

LOL, AIG would fail :P

Some people with bigger setups designed the same way I did mine have had issues with popping the front windshields rubber seal or cracking the glass where the rear view mirror is attached. Mine wont do that, I'm really only getting about 1300rms outta my amp since my stock alternator is 100amps, 100amps x 13.5volts = max 1350rms, not to mention the headlights turn signals and everything else Im really only getting 1100rms. Most people never take that into consideration when building a hi-spl setup. It's all about the power you have on tap. People that run multi H/O alternator setups are the ones popping window seals and breaking glass. I always have my sunroof cracked to let some air out just to be safe.

[SHiZNiLTi]

Check out this door flex...

[87ghosts]

I really need your help with a box design. Ive built some sealed and some ported boxes and have had good luck with them so far. I don't have the money to build multiple boxes to learn to build a 4th order box. I just acquired a 1999 lexus es300 and I need a box like this for two alpine type r 12's. I know it takes a lot of time and effort to do the math. I would greatly appreciate any help you can give me.