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BambooU

Speaker Boxes. Do I need them?

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Hey y'all. If there is previous topics about this, I'd love a link to it.

 

I'm wondering at what point does it become necessary to have speaker boxes for speakers starting at say 6x9. Is it something only for big speakers? Is it only needed for subwoofers? 

 

I question this because the place I want to put my speakers leaves me with precious little room. Im taking my back seat out, and want to put two 6x9's where the top backseat used to be (In the holes). The clearance issue is obviously the gas tank. 

 

So this is my main question: Will my 6x9s sound like shit without speaker boxes? 

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No you'll be fine.... most the time a 6 1/2 or 6x9 is stuck on that panel behind the seat.... bottoms were just open to the trunk... the do make baffels of you really want.... you could also make a trim ring to space it up a little for clearance...

 

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I think alot of times why you see those 6x9 boxes is to give some a place to mount a speaker like in a truck behind the seats.... I've only built boxes for subwoofers....

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The front and back air spaces need to be separated. This is either done with a box or an "infinite baffle" eg the rear deck & back seat usually separate the front & back of the speaker creating two sides (cabin & trunk). A free-air speaker is unloaded and cancels itself out quickly, especially in the lower frequencies. A box is the easiest way to accomplish this, but too small of a box also is harmful to accurate/linear frequency reproduction.

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This!

 

Front and back separated by partition or a box.

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Alright, so my understanding is that as long as there is a separation wall between the front of the speaker and the back of the speaker, it'll be fine. 

 

So given a board like the template i have shown is put there, with speakers in the two gaps, will that be enough to seal it?

 

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Alright, so my understanding is that as long as there is a separation wall between the front of the speaker and the back of the speaker, it'll be fine.

 

So given a board like the template i have shown is put there, with speakers in the two gaps, will that be enough to seal it?

 

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More or less. The better sealed it is, the louder it will be up to a point. Since it is still essentially "free air" it won't be able to handle as much power.
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More or less. The better sealed it is, the louder it will be up to a point. Since it is still essentially "free air" it won't be able to handle as much power.

 

Hm. Alright. I'll need to troubleshoot and do more research before picking up the stereo set, then.

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Most factory rear speakers are this way, so you should be fine, just don't expect too much in the bass department

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Hm, wonder if having 6x9s next to the fuel tank will shake loose 50 years of scale inside the tank ?

Ultrasonic tank cleaning while you get down to your music :)

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Hm, wonder if having 6x9s next to the fuel tank will shake loose 50 years of scale inside the tank ?

Ultrasonic tank cleaning while you get down to your music :)

 

shake off the rust. that's the plan!

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You could look for some vintage Package Tray speakers. A few of the guys down here are using them and they actually sound pretty good. 

 

Plus, you don't have to cut up your car. 

 

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The trunk is a bit large for a speaker box for a 6x9. It's better than no partition but an enclosure around it would be better. The enclosure air will act as a compressible damper preventing over driving of the voice coil but too small will restrict it.

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How small is too small for 6" x 9" speakers or better yet what would be the correct size?

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Probably only need to be .3 to .5 cubic ft... they actually sell premade boxes cheaper than you can make them now.....

 

The biggest thing that people miss is that a 6x9 is not a subwoofer...

what frequency you play through the speaker and how loud is important...

 

If your trying to control the 6x9 to get some bass out of it a box will help but only to a certain degree.... again it's not a subwoofer....

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Premade may not fit your application. My old Omni had a space above the diff where a 510 has a gas tank. I made an enclosure that fit this space with the two 6x9s up against the holes in the deck under the rear window. You could also lift it out for more room.

 

 

Those boxes that fit on top of the deck block the view, sound like shit because too small and look worse.

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A speaker box does two things.  Like was mentioned control or limit cone excursion, and second, acoustically match the speaker to the area it is in.
You can control cone excursion by limiting power to the speaker.  A second problem with a car or truck is every time a door is closed it builds pressure in the car temporarily, and pushes the speaker towards the outside of the car.
 
Acoustically matching the speaker is way more involved.  Each speaker has a set of parameters that among other things gives the speaker cone a resonate frequency.  A heavier speaker cone will resonate at a lower frequency.  A tighter cone suspension on a speaker cone will have a higher frequency.  A smaller speaker will have a higher frequency.
Another factor in a speaker box is that when the speaker moves out, it makes a positive pressure in front of the speaker, and a negative pressure behind the speaker.  If you do not isolate the back and the front of the speaker from each other, these two pressures tend to cancel, and you lose response at lower frequencies.  Additionally, you lose any control on cone excursion.
 
A closed box of the right size will control cone excursion, but limits low frequency response, because it just damps, or throws away the sound from the back side of the cone.
A ported box, of the right size can give you a lower frequency response in a same sized box, or a similar frequency response in a smaller box, and an increase in audio volume in either case, because a ported box uses the back side of the speaker.
 
Some speaker manufactures will give you data on each speaker model about what size of box the speaker works with and the frequency you need to tune the ported enclosure to.  
 
 
I do sound for high school dance competitions.  I build a pair of subwoofers for my sound system.  The subwoofers are a 14 cubic foot ported box, with two Electrovoice DL-18-W speakers, tuned to be flat down to 34 Hertz.  For reference, Low "B" on a five string bass guitar is about 32 Hertz.  Low frequency rolloff on the subs is 12 DB per octave.

My sound system in a high school gym.
ReynoldsFar.JPG

The speaker stack on the stage left side of the gym.
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The speaker stack on the stage right side of the gym.
ReynoldsStRt.JPG

Close view of the amplifiers. There are three amplifiers I use, the subwoofers are using the bottom amp in the top amp rack.  this amplifier is a Fender 2244, FTC rated at 440 watts RMS per channel, into a 4 ohm load.  The wood box main speakers use a SAE P-250 amp, FTC rated 250 watts, RMS per channel, into 8 ohms, and the plastic main speakers use a QSC PLX 2402 that is about 500 watts per channel, into 8 ohms.  The main speakers have a 15 inch woofer, and a 1 inch compression driver horn.  there is a external crossover, set at 160 hertz, with lows going to the subwoofer Fender amp, and the mains get everything above 160 Hertz, and use their internal passive crossover to split the midrange, and treble frequencies.ReynoldsAmps.JPG

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Well that's a very in-depth answer....

I think alot of that really comes in to consideration in higher powered systems...

You can make a cheap radio and speakers sound good but at low the volume...

I found as you get louder everything you said really matters. ..

I bet that system for the high school sounds amazing and loud as hell in that environment.... put the same system in a open air event and I bet it sounds totally different... you can probably make it sound good outside but I bet you have to adjust your amps and settings....

Cars and trucks are no different..

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I had 6x9s in the rear deck and 5" in the front door.

Can't remember if I had an amp, but the sound was good.

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My original plan was to install 6x9s into my rear luggage rack deck. But after installing my rollbar (making that seating space unusable) the opportunity arose for me to tear out the back seats and putting boards back there. So that's what I did.

 

Updates; I currently have the boards in place, but without holes for the speakers. I'm waiting on the tools to cut it properly (I'm living far  enough away from my tools that I can't work on it daily). Once I get the speakers mounted and installed, I'll post pics. 

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OP, as long as you seal the piece you made and the holes in the parcel shelf, you should be good. My daily 07 Crown Vic has the speakers mounted in the parcel shelf, everything else is sealed from air leaks. With a pioneer double din deck and new pioneer ford specific 5x7s it’s amazing how well it sounds. Great mids, punchy bass, nice highs.

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