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Custom downfiring enclosure

 

Unregistered guest
My friend and I are both going to be getting subs soon. I drive a jeep grand cherokee and he has an audi a4. We are both planning on building similar boxes, so we will both be able to help each other out. I was thinking of making the subs downfiring and making the box out of 3/4" mdf on three sides and make the front 1/2" or 3/4" plexiglass. I would then put it on 2" stilts so the subs would have some clearance. Then I could put some neon lights in the box and maybe put mirrors all around.
It would look something like this.
http://img.photobucket.com/albums/v190/eric77/subs.jpg
And similar to this box. Would there be any advantage to sealing off each sub like in the picture below? Or should I just have the 2 subs sharing the same air and not seperate them like below?
http://jlaudio.com/Gallery/Upload/Dsc00612.jpg

Do you thnk that this would be a fairly simple build? Also, would I just build the main box like a regular sealed box and then just place it face down or is there some special way to design a box for downfiring subs? Do you think I could still get good sq and some spl out of this. BTW, Im probably going to get two diamond MKIIM6's powered by either a memphis 16-MC1000D or by an elemental designs nine.1 Thanks.
eric
 

eric77
Unregistered guest
B U M P !!!
 

Silver Member
Username: Audiobahn_man

Freakmont, MI

Post Number: 265
Registered: Aug-04
Hey sounds like a nice box if you do it right, plexiglass is very very expensive and it cracks, and scratches very easy. u need to predrill all holes and make usre not to scratch it. Dont use anything less than 3/4, or you will get massive flex.
 

Big D
Unregistered guest
Yo Eric,
Form follows functionality. Forget the downfiring. Thats just going to cause vibrations, fire the thing right at you. Your SPL and SQ are going to do exactly what you want...drop to the floor

I know this is my opinion but I gotta tell ya,
Forget the lights and the plexiglass. Do you want your sub to look like some kind of space ship? Sub is for sound! Not visual. Throw the lights above your pedals and same place on the passeneger side...you appreciate that ambeiance more than some blue or green light from behind.

But have fun building that bad boy.

-peace
 

Silver Member
Username: Audiobahn_man

Freakmont, MI

Post Number: 267
Registered: Aug-04
wow, your dum, down firing boxes actually work nice in SUV's and Pick-up extended cabs. Dont listen to this joker...he has no idea what he is talking about....and for firing them toward you, that is about the worst thing you could do because the waves arent able to bounce off anthing and will result in lower spl and sq. Depending on what you plan on doing, I think the lights and such would look nice....
 

Bronze Member
Username: Slap_johnson

Arizona

Post Number: 97
Registered: Aug-04
dude, u get a huge cabin gain downfireing and gives a cool effect
 

Big D
Unregistered guest
Waves are not able to bounce off anything? Bouncing waves are DISTORTOION which slap calls that "cool" effect. You don't know who your talking to so I wouldn't be calling me dum. This audiobahn_man is just about as reliable as their products.
 

New member
Username: Howlow

Post Number: 9
Registered: Nov-04
alright, this is my experience from building different enclosures, i found that firing my subs into the rear of my car sounds a hell of a lot better and deeper and louder all around than when i have them firing into the cab, i ported bt rear deck and removed my speakers. ive never had n e experience with a down firing box, youll have to let me know how that one works
 

Silver Member
Username: Jeremyc

Kunsan AfbSouth Korea

Post Number: 149
Registered: Jun-04
Big D, distortion is caused by the amp clipping, therefor producing a square wave instead of a sine wave. Distortion has nothing to do with bouncing a sound wave off of an object. To be exact it takes about 4 to 6 ft for a low frequency wave to form. By firing the speaker down you give the wave time to form before it reaches your ear.

Now that we settled that, on to the people who have a clue. I wish I had my computer with me, I have some really good pics of the down firing box I built for my S10. As for seperating the speakers, I do perfer to. I feel it works out better since most speakers aren't perfectly matched.

Here is the basics on my box, if you want I can send you some pics once I get home.

I scribed my box to the floor, on all four sides, and cut a semi circle from the floor up about 3.5 inches. Then I took grill cloth wraped it from the front of the box, around the opening and stapled it to the peice of board the sub was mounted to (underneith the box). Once I got it like I wanted I coated it with fiberglass resin and let it dry. After that I put a coat of bondo and then sanded it smooth. Its alot of work but it give the sound wave a smooth area to travel thru, and alows you to control the direction the sound wave travels. Once this, and everything else was complete with the box, I bolted it to the floor, making sure it was good and snug. If the box moves easaly it can cause some problems.
 

Big D
Unregistered guest
you are a fool. Do you like the sound of Bose?
 

Silver Member
Username: Jmloughrey

Farmington, CT

Post Number: 392
Registered: Jul-04
Jesus, put your ego's aside and help the kid, you both made good points.

Alright, plexiglass....as stated besure to use atleast 3/4in and DO NOT layer it, i repeat DO NOT layer the plexiglass, no matter how many screws you use you will get a horrid vibration sound when your sub hits and you'll just want to throw the box out the window.

full fiberglass boxes can sound and look amazing if done properly...these are quite a bit moe expensive and alot more time consuming and painstaking effort, but if thats your thing go for it.

As for MDF, i've found it to be the best/easiest form of enclosure, not to mention you can cover it in carpet and hide any imperfections, since you have an SUV there will be times where you dont want to take your box out when you've gotta haul something, this would be a problem with MDF and fiberlgass, you cant really place things ontop of it, with MDF, place away.

Thats just my thoughts because i have a Jeep just like you.
 

Silver Member
Username: Jmloughrey

Farmington, CT

Post Number: 393
Registered: Jul-04
Jesus, put your ego's aside and help the kid, you both made good points.

Alright, plexiglass....as stated besure to use atleast 3/4in and DO NOT layer it, i repeat DO NOT layer the plexiglass, no matter how many screws you use you will get a horrid vibration sound when your sub hits and you'll just want to throw the box out the window.

full fiberglass boxes can sound and look amazing if done properly...these are quite a bit moe expensive and alot more time consuming and painstaking effort, but if thats your thing go for it.

As for MDF, i've found it to be the best/easiest form of enclosure, not to mention you can cover it in carpet and hide any imperfections, since you have an SUV there will be times where you dont want to take your box out when you've gotta haul something, this would be a problem with plexiglass as well as fiberglass, if your box is carpeted MDF, you dont have to worry about scratchs...not to mention dust...

just my thoughts seeing as i have an Jeep just like you do. Take it into consideration...
 

Unregistered guest
Thanks for all the help guys. One more question, I think I am going to be getting the diamond twelves now because I realized I want more bass. Diamond recommends that in a sealed enclosure the M6 12" woofer should have .875 or 1.25 ft3. Which volume should I go with? Or if I go with anything in between should I be alright?
Jeremy, Id really appreciate it if you could send me those pics if you get a chance. My e mail is e_eadington@yahoo.com Thanks.
 

Bronze Member
Username: Slap_johnson

Arizona

Post Number: 98
Registered: Aug-04
by the way your going to want to use lexan instead of plexi, dont listen to anything big d has to say, ive expiermented with the box faced up, down fired, and into the seats, i found that downfireing and faceing them straight up work best, and fireing them directly at the seats gives the wave no time to form, you will also lose so much of a cabin gain you could have by downfireing, also if your worried about vibrations use dynamat
 

Big D
Unregistered guest
Distortion - Anything that affects the signal being transmitted from the souce transmitting the signal (sub) and the object recieving the signal (ear).

Clipping is an expample of distorion. I agree.

What we appear to be argueing is completley personal prefrence, I am speaking from a pureist
POV, Slappy is talking about boom and "sounds better"

Pure and Sonically Pleasing can be 2 different things...I hope we call all agree on that.

Oh and Steven, aren't you in High School? Take some College Level Physics courses and then we can be on the same level.
 

Silver Member
Username: Jeremyc

Kunsan AfbSouth Korea

Post Number: 152
Registered: Jun-04
Eric
Slap is corect on the lexan. It dencity is alot higher than plexi, so it is alot stronger.
As for the pics I get to move out of my tent and back into my dorm on the 24th. I will send them shortly after. As for your demensions it depends on your amp and what type of music you listen to. I listen to all types of music and try to always match the sub and the amp the best I can. So I would go with 1 cube, and wouldn't worry much if I lost or gained a little with my box design. Keep in mind though some subs are very picky. The Boston Pro 12 is very picky about it's box. So I would double check with some instalers that deal with those speakers, and see if they have the same problem.
 

Silver Member
Username: Elecgenius

La Puente, Ca United States

Post Number: 137
Registered: Oct-04
http://www.teamrocs.com/technical/pages/aiming.htm

as u guys can see,, the bounce on the trunk causes the soundwaves to be concentrated to a certain point, which is , per say, like a laser beam instead of a shotgun. it concentrates the 'beam' into one direction and does not 'spread the BB's from the shell' all over the place ( in which place u would have sound bouncing all over the wall in all directions. of course. the sub and other things come into place. i guess it all comes down to how it generally sounds better, and , let me tell u,, theres a reason why they make donfiring enclousers for trucks a lot more often than on cars with trunks.----------------------------------forget me, just read the article,lol,
 

Bronze Member
Username: 54danny54

Post Number: 39
Registered: Nov-04
Downfiring looks awsome...juss dynamat the ground b4 u install it
 

Bronze Member
Username: 54danny54

Post Number: 40
Registered: Nov-04
it might reduce the distortion a bit
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