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List of parts to build a speaker box

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=34103
Printed Date: March 28, 2024 at 3:54 AM


Topic: List of parts to build a speaker box

Posted By: markcars
Subject: List of parts to build a speaker box
Date Posted: June 17, 2004 at 11:02 PM

I am in the process if building a box for my new sub that hasnt arrived yet, but would like to know what are the list of parts I would need like liquid nails etc and where I can get them all. I looked up the net a bit but did not find any place with a complete guide.

Also if the size of the box needs to be 40 liters in volume, does it matter if the shape is shallow and very wide, as long as the volume is within the specs? Because I want to build a box that is as shallow as possible, probably just about an inch behind the magnet and then as wide as my trunk space so that I can fit the box well in my trunk with it being minimally obtrusive. thanks.



Replies:

Posted By: bLACKKNIGHTPRES
Date Posted: June 17, 2004 at 11:24 PM

Im guessing your new at this.. my first box was made out of 3/4 MDF wood.. you need screws.. a jig saw.. circular saw.. a drill.. some silicone sealer.. carpet? ur choice.. and the connectors, have fun!



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BlacK KnighT RacinG




Posted By: Ravendarat
Date Posted: June 17, 2004 at 11:25 PM

If this is for your focal sub you need 3/4 inch mdf with internal bracing or 1 inch thick mdf if internal bracing isnt an option. The box can be built fairly shallow as long as the internal volume  is right. You are also gonna need either brad nails or screws, I know this is gonna start a debate but I have used both and never had a problem with either one. Your gonna want silicone to seal the inside of  the box with. You are also gonna need a way to get the wires to the outside of the box. You can either use a terminal cup or you can drill a whole and then run the wires through and silicone it up. If you use a terminal cup dont use a cheap one and silicone the hell out of it since some termianl cups leak air through the actual connections, very uncool. You are gonna need something to cover the box with, if its carpet then you are gonna need a can of airsol spray glue, if you vinyl then you need staples and some type of glue to hold it down, I dont know whats avalible in your area. I think thats everything. f you think I am missing something just ask.



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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer




Posted By: icu400
Date Posted: June 17, 2004 at 11:30 PM
First, as far as I know, the shape as far as that goes does not affect the sound in any way, only the volume.

Now, I am betting you want to build a sealed enclosure (meaning air tight), so here is what you need:

one large sheet of 3/4" MDF
1 large tube of liquid nails, or 2 smaller ones
1.5in coarse drywall screws
a jig saw and circular saw, and power drill
a speaker terminal (put wires from amp on side on outside of box, and connect sub to opposite side inside box) (get this from radio shack)
and a form of sealant (RTV i believe it is called) to seal all the seams

everything but the speaker terminal you can get at home depot or lowes, the mdf is about 20 bucks, the liquid nails about 4, the screws 1-2, the terminals a few bucks a piece, and the sealant should not be much either (just ask a guy at home depot what he recomends

basically you cut the MDF (which is a higher quality plywood) and glue it together with the liquid nails. Make sure you cut the holes for the driver and speaker terminal first. Then just use your drill to put the screws in ever few inches (they don't require pilot holes but you are welcome to drill them). After that, use the sealant on all the inside seams for an airtight finish, cover with carpet of your favorite flavor, stick that sub in there and bang away.




Posted By: markcars
Date Posted: June 17, 2004 at 11:38 PM
Thanks a lot for all your helps.

I don't know what is bracing.

This is going to be my first car-sub box, although I build speakers long ago for my home use, but never a real sub. This seems very interesting and exciting. And Ravendatat, yes its for my focal. And icu400, you win the bet. How did you know I was wanting to build a sealed box?   This brings to another interesting question that I had in my mind. I thought of putting in a port in the box, but put a port cover, so I can close the port and listen to the sealed box, or open the port to hear the ported version so I can compare both and see which is better and eventually seal the hole if the sealed version is better. I still am not sure if ported or sealed will sound better.   

Also I don't know what are liquid nails yet. Ill be spending some time at home depot surely.




Posted By: Ravendarat
Date Posted: June 17, 2004 at 11:46 PM
The sealed ported Idea is not a good one if its a wedge style box. The port would be complicated and the internal space for a ported bos is quite different from that of a sealed box. If you wanna compare then you are gonna have to build 2 seperate boxes. I have made convertable boxes before but they were complicated and never in a wedge style although I know that its possible. If you really wanna know I can tell you how I did it in detail but if this is your first attempt I would suggest even trying. There is a lot of math involved and its kinda complicated to build properly.

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer




Posted By: auex
Date Posted: June 17, 2004 at 11:47 PM
I hate liquid nails, hate it, hate it, hate it (get the drift). Liquid nails is like wood glue but alot thicker and comes in tubes just like silicon. To many people swear by it and I hate the stuff with a passion. I prefer wood glue with brad nails to hold the box together and I seal with fiberglass resin. Also do not try to make a selectable ported box without some type of membrane that will increase the volume of the box easily, sealed boxes are too small for ports generally ( I really wouldn't recommend this for anything then other a competition vehicle). Bracing would entail placing pieces of wood inbetween the top and bottom, sides, and front and back to support the box from flexing. And to prove my point about liquid nails, see posts below trying to flame, hehe!

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I've been sick lately, sorry I won't be on much.




Posted By: icu400
Date Posted: June 17, 2004 at 11:51 PM
Liquid nails are a nice way of saying glue, but they work very well.

As far as changing for ported to sealed thats not possible. Ported boxes require twice the volume of a sealed box, and if a sealed box had double the recommended volume, it would sound like crap.

Some people like sealed or ported more. The rule of thumb I have learned is sealed for quality because it has more control over the sub, but ported for "louder" applications. I use sealed on my subs, I am using sealed on the new boxes I am building. I have only heard 1 other ported box, and it sounded ok, but sealed is easy to build and is generally associated with sound quality. I would just look at like this: if you don't like the sealed, you will have enough left over wood to probably build a ported, or you could spend another 10 bucks for some more mdf (you will have plenty of screws/liquid nails) and another 5 bucks for more terminals, and build a ported and see if its any better. But I bet you will be happy with sealed.

Peace.




Posted By: icu400
Date Posted: June 17, 2004 at 11:53 PM
Liquid nails are a nice way of saying glue, but they work very well.

As far as changing for ported to sealed thats not possible. Ported boxes require twice the volume of a sealed box, and if a sealed box had double the recommended volume, it would sound like crap.

Some people like sealed or ported more. The rule of thumb I have learned is sealed for quality because it has more control over the sub, but ported for "louder" applications. I use sealed on my subs, I am using sealed on the new boxes I am building. I have only heard 1 other ported box, and it sounded ok, but sealed is easy to build and is generally associated with sound quality. I would just look at like this: if you don't like the sealed, you will have enough left over wood to probably build a ported, or you could spend another 10 bucks for some more mdf (you will have plenty of screws/liquid nails) and another 5 bucks for more terminals, and build a ported and see if its any better. But I bet you will be happy with sealed.

Peace.

(P.S. make sure your volume meets the factory recomendation for your sub, other wise it won't sound quite so good...best of luck)




Posted By: Ravendarat
Date Posted: June 17, 2004 at 11:55 PM
Its not impossible, just far more dificult.

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer




Posted By: icu400
Date Posted: June 18, 2004 at 12:01 AM
Auex: I won't flame you; before I came here, I never knew about liquid nails, and I had been building various items like doors, windows, bookshelves, and tons of other props for a local theater group for more than 2 years with nails or screws and simple wood glue, and never had a problem with it

But I just used liquid nails to make 2 enclosures, the sealed box for my 2 subs, and a sealed custom box for under the seat of my friend's f150 truck. We used resin to seal his box, since it was really wacky shaped. I never had a problem with liquid nails. If anything I thought that it stuck better than the wood glue, but I am sure the wood glue would have worked fine.

I am just curious why you have so much hate for the liquid nails mate, thats all :P




Posted By: markcars
Date Posted: June 18, 2004 at 12:05 AM
Ok then so far I think I will get back to my origial want, which is a sealed box, since I am after quality more than anything else. Definitely going to go with sealed box.

I once went to Best Buy and they had a box that had a port that could be removed, which the sales guy said was for the same reason but I wonder why they even sell that. I guess they can sell anything but we got to be careful of what we're buying.

And thanks for the info on bracing adn liquid nails. Very useful info to me.

Also Focal's site shows 30 to 50 liters volume both for sealed or ported. I wonder why they have the same volume for both types. Here's the link on Focal's site

Also whats the difference between having a rectangular box and a wedge shaped box? Anything to do with sound quality?




Posted By: icu400
Date Posted: June 18, 2004 at 12:08 AM
I stand corrected. Perhaps "impractical" would be a better word than "impossible"

I simply meant that a sealed enclosure that had double the recommended volume would not work too well.




Posted By: icu400
Date Posted: June 18, 2004 at 12:10 AM
Wedge shaped fits better in a "hatch back" vehicle. NO difference in quality.




Posted By: icu400
Date Posted: June 18, 2004 at 12:18 AM
I don't know whats up with their volume recomendations. From my calculations, 30 liters is a tad over 1 cu. ft. So somewhere around there and you should be fine i suppose.




Posted By: Ravendarat
Date Posted: June 18, 2004 at 12:22 AM
The key to making a convertible box is to design it so that when its in a sealed fasion its not double the size but actually the recommended size, and when its in ported fashion the trick is to make it so the box is not half as big as what its suposed to be but actually the perfect size. Im off to bed tonight but if you wanna know what the hell Im talking about,PM and Ill explain it tomorrow. Also I find a lot of recomended specs to k=be kinda inacurate and pretty much suck donkey dick. Most manufactures give you the smallest space you can use the sub in without causing damage but no nessasarily the best size. What comes to mind is Pioneer. They say for their subs you need 1.4 cubic feet sealed and 1.5 cubic feet ported. I thought that was BS so I made one box ported right to spec and then another box ported to 2.25 cubic feet and not a single person thought that the pioneer box sounded better than the one I built. This is something that comes with experience and knowing whos numbers to trust and which numbers sound right.

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer




Posted By: icu400
Date Posted: June 18, 2004 at 12:53 AM
I have sort of gotten a feel that for most subs that I am familiar with, which are mid power range 10's, many of them use sealed enclosures around .7-.9 cu ft. Below that and I start to wonder, and above that I disregard since they won't fit in the space I am working with :P




Posted By: markcars
Date Posted: June 18, 2004 at 8:01 AM
So far I understand that I should not take the manufacturer's size specs too seriously. That makes me confused as to what size I should build my box. If the manufacturer says 30 to 50 liters, is 40 a safe number I can assume? Also the pro sound shop I had visited this past weekend told me that "a wedge shaped box somehow sounds better than a rectangular shaped box, I don't know why but it just does" those were his exact words, but fo course I did not believe everything he said.    

Also has anyone ever used this device that supposedly improves bass quality? Its rather expensive for what it does. Heres the link: https://www.speakercity.com/Sos/SubwooferOptimizer.shtml






Posted By: DYohn
Date Posted: June 18, 2004 at 10:26 AM

markcars wrote:

So far I understand that I should not take the manufacturer's size specs too seriously.
 

NO, this is incorrect.  If you are dealing with a reputable manufacturer (like most of the brand names discussed on this forum) they are very careful to recomend safe, good sounding enclosure sizes for their drivers.  Use the T/S parameters supplied with your driver and make your own decision, of course, but if what you come up with is too far off from the manufacturer's specs then it is more likely that you have done something wrong than that they have.

markcars wrote:

Also the pro sound shop I had visited this past weekend told me that "a wedge shaped box somehow sounds better than a rectangular shaped box, I don't know why but it just does" those were his exact words, but fo course I did not believe everything he said.     .
 

He is correct.  A perfect square is the worst possible enclosure shape and a perfect rectangle is next worst.  A wedge shape ensures the back wall is not parallel to the front baffle where the loudspeaker mounts.  This helps minimize standing waves inside the enclosure.  Now, in most car audio subwoofers, the frequencies being generated are low enough and the enclosures small enough that this can be pretty much ignored, but that's the logic behind the statement.  HERE's a reference for you.

markcars wrote:

Also has anyone ever used this device that supposedly improves bass quality? Its rather expensive for what it does. Heres the link: https://www.speakercity.com/Sos/SubwooferOptimizer.shtml .
 

Those kinds of active processors can make a big difference in some systems and none at all in others.  If you have the money to play with it, it can't hurt and you can always remove it if you don't like what it does to your sound.



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Posted By: icu400
Date Posted: June 18, 2004 at 10:34 AM
Couldn't you just make a "rectangular" box and fill it with polyfil/acousta-stuf and that would eliminate the standing waves too?




Posted By: DYohn
Date Posted: June 18, 2004 at 10:46 AM

icu400 wrote:

Couldn't you just make a "rectangular" box and fill it with polyfil/acousta-stuf and that would eliminate the standing waves too?

Polyfill can have some effect on dampening standing waves inside an enclosure, yes.  Lining the walls (or at least the back wall) with genuine acoustic insulating foam (like this or an equivalent) is actually a much more effective solution for correcting standing wave problems.



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Posted By: _DIZZ_
Date Posted: June 18, 2004 at 1:57 PM

I just build a sealed slant box for my Honda. It took the better part of a day. But I am a drafter, so I drew it in AutoCAD first, so it was easy to figure the angles. As for tools, I found that the circle jig for a Rota Zip works excellent for the speaker cutouts





Posted By: markcars
Date Posted: June 19, 2004 at 9:53 AM
Thanks for the tip. I have the Rotozip complete toolkit, but never really used the circle jig yet. It can make a perfect clean circle easily with just giving the center point and the radius. I will use it in my project surely.
Also by filling the box with Acousta Stuff, will that help get rid of free standing waves in the event I have the back wall parallel to the front wall(where the sub is mounted)?




Posted By: mobile E
Date Posted: June 20, 2004 at 12:29 AM

as far as glue goes... the best stuff is construciton grade polyurithane (i think thats how you spell it?) This stuff is twice as strong as liquid nails .. and it has tensile strength..

Matt





Posted By: markcars
Date Posted: June 21, 2004 at 8:20 AM
hey Mobile E, where do I buy that? construction grade polyurethane that is. I would like to try that.






Posted By: mobile E
Date Posted: June 21, 2004 at 11:30 PM

you get the stuff at home depot... it comes in a yellow and brown bottle... and i talked to the glue guy there and he says great stuff about it... but use gloves , because its hella hard to get off youre hands, but i swear by it...posted_image

Matt





Posted By: markcars
Date Posted: June 22, 2004 at 9:04 AM
Thanks for the info. I am going to definitely use polyurethane . I've read that on some very good speaker building sites and even on parts express's how to build speakers section. And you said it to and you swear by it, so I can bet its going to be really good and I am going to use it too.





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