Box shape

OK, I've read just about every thread dealing with boxes, sealed vs ported, bandpass, etc. For my listening tastes, I think I've decided on a sealed enclosure, mainly because I prefer SQ over loudness. I know, it's a little different than most people, but that's me.

However, I've only seen a little bit comparing cubic shaped vs tubed enclosures, and I was curious about the advantages and disadvantages of each. I was also wondering about hybrid designs, with say, a smallish cube just big enough for the sub with a big PVC pipe embedded in it to bring up the total volume. Please don't flame me, I'm a beginner at this stuff, and I don't really know the do's and don'ts of this art. Also, what about 3D orientation? Does the sub have to point directly back or can it be pointing up or sideways? I know forward is bad, so that direction is out. Ideally I'd like to take some of the space in the back behind one of the wheel wells so I can still use most of my trunk.

I'd like to build something interesting to look at that sounds good from the frequencies of like 20 Hz to like 200 Hz (or where ever the midrange speakers start to take over). I don't really want to go totally loud like most of you guys do (no offense), so sound quality over the whole range at lower volume levels (like less than 100 dB) is what's important to me. I have some nice 3/8" lexan I'm planning to make at least one side out of, for a window with some lights :naughty:.

As far as what I have to work with: I got a decent deal on a used Rockford Fosgate 15" hx2 sub (with the 4 ohm dual VC's) and a Soundstorm F500.2 amp. I know these aren't the best stuff out there, but it's what I can afford. Being able to get like 400 Watts out of $160 isn't too bad I would think. I have a '93 Honda Accord EX sedan, with a good Panasonic head unit and some pioneer coax mids.

Sorry this is so long, but these are the questions I have after reading for like 3 days.

Summarized:

speaker box: square vs tube (hybrid?)
cone orientation: straight back vs up, sideways, etc
frequency range?

Thanks guys!

not an expert just giving my 2 cents..

as far as i knwo there is really no difference between round enclosures and square ones. I would think that the only thing that matters is volume. shape probably doenst have an effect. most people build boxes because theyre easy. therefore, i doubt a hybrid would even do anything except take up volume in your box. i would suggest just an MDF box. or a fiberglass box if you cant get one done.

as far as where to point your subs.. it depends on your car. i wouldnt suggest firing them to the side. ive heard a car liek this and it wasnt good. most people fire them back, but you might want to try flipping a box around back there and seeing what sounds best.

and the frequencies.. yeah youll need sealed to get the range you want. hoewver you wont get good responce from your sub at 200 hz trust me. most people have their mids take over at like 60-90 hz.(i think) mine are at like 80. how good are those infinities? i doubt your midbass will be very strong, but id say 80-90 hz would be good.

the sub is ok, but more meant for getting loud. actually from what i remember this sub had very poor sound quality, but youll figure that out after you get it in your car and listen to it for a while.

is your amp a 2 channel? im assuming its only stable down to 4 ohms bridged.. problem there being you cant wire your sub for 4 ohms. you would haver to wire it to 8 ohms and then youd really only be getting like 200 watts to your sub. dont knwo the specs on either sub or amp but may want to look into this.

if you end up haveing to get rid of one or the other, ditch the sub and check out an atlas 15 from ascendant audio (www.ascendantaudio.com) BUT.. get back with us first about whether that amp will work with the sub.

ok, the sub is rated as follows:

Frequency Range: 24-200 Hz
Dual 4 ohm voice coils rated to 300 Watts each
Q factor: 0.53 Qts (quarts?)
Recommended Box volume: 2 - 5.5 ft^3



amp specs:

Input level adjustment
Line level & speaker inputs
Freq resp (+/- 3 dB): 9 Hz - 50 kHz
Variable low pass crossover: 40 Hz - 150 Hz
High pass crossover
THD @ RMS output: .01%
Variable Bass Boost: 0 - +18dB
S/N ratio: 103 dB
Channel separation: 90 dB
Power MAX 2W 500W x 2
Power RMS 4W 200W x 2
Bridged Power 1000W x 1
Damping Factor 125+

I was thinking about hooking the connections up in parallel so it's a 2 Ohm woofer and just using a single channel on the amp. That way it's using 500 watts of the rated 600 watts, which is close enough for me. I could also use both channels in 4 ohm mode for a total of 400 watts. I guess either way would work.

It's going to be a few months before I can actually install and test this, because it's so freakin cold outside. (it's -5 degrees F at the moment) I would like to build the box anyway, and maybe if there's a mid winter thaw, I could install it then. Luck favors the prepared, I guess.

Anyone have a response to "box shape doesn't matter as much as total volume enclosed"?

do you already have the equipment? I would suggest different things for a sq setup.

I know there are tons better things out there, I'd just like to get the best sound possible from 160 bucks worth of stuff. I do already have the equipment, and I doubt I'll be upgrading anytime soon. I'm gonna have some fun making the sub enclosure though, so it isn't all bad. I figure if I can design something that makes a crappy setup sound pretty good, I'll have learned enough by the time I have the money to get a really nice setup, I'll be in good shape to make that sound incredible.

For the moment I'm wondering if it's just volume of the sealed enclosure that matters or if it has to be a generally regular shape (cube, tube, sphere, etc).

You won't get any SQ worth worrying over the box with that sub. As for your assumption about a lot of us choosing SPL over SQ, it's quite the opposite here.

As for the box, most people make a rectangular or cubed box, but I think usually rectangular. No weird shapes or designs. It becomes difficult to measure the proper volume inside the box and makes sound travel weird in it (this is just stuff that sounds right to me, some of it I'm sure of, but the shape thing with the sound travel I'm not). Take my advice with a grain of salt, a large one.

shape doesn't matter in a box, only volume. The problem in making odd shapes is figuring out the volume and making it rigid (so it won't flex)

perfect cubes are the absolute worst sound producers. The golden ratio is optimal. 1W*0.618D*1.1618H or at least that is what the myths say.

Make a triangular box.

ummm ... if it were a triangle, it wouldn't really be a "box" ..... but it would be an interesting looking enclosure Sometimes a cube can have standing waves, they are generally avoided

So I was 50% accurate with my post, I'm catching on and learning :).

has anyone used PVC pipe in any part of their boxes before? I know it's not a usual material, but I don't like to do things the standard way. A little variaty and experimentation never hurt anyone :). Because of space issues I was thinking about using some 6" diameter thick walled PVC as extensions through unused parts of my trunk. I've done a bunch of calculations, taking the thickness of 3/4" MDF and the sub, and the approximate volume of my design is 4.5 cubic feet, which is near the upper limit of the sub's sealed enclosure rating. I can add some stuffing to simulate a larger volume too. I'll work on some sketches with a picture of my trunk and post it later today. You're probably going to think I'm nuts, but like I said, I like to experiment.

you have no idea. we used 6" Irrigation PVC to make a TL for one of thoes old audiobahn 6" woofers. Probably some of the best SQ i have heard from audiobahn. and we had good responce down to 30Hz (40Hz tuning). and we used some of their sweeping elbow's to make the curves. it worked out nice. he used 0.87kg of acoustic whool stuffing (i didnt do the calcuations, dont ask me about stuffing to change tuning, i know alot for such a youngin' but not that much) to lower the tuning frequincy and it turned out only needing like 7ft of line length.

a 6" subwoofer ? ............... the only problem with pvc is it's not to strong and may flex with more powerful subs.

That's what's nice about tubes... a little bracing is really easy. Just crank a couple of large hose clamps on it and it won't flex much. I'm getting pretty close to a final design, after carefully measuring the inside of my trunk. I don't think I'll have any pics tonight though, sorry. I was fighting with a friend's computer all afternoon.

yep. audiobahn used to make some 6's. look on Realmofexcursion.com there is a video of some guys with 2 of them in a massive TL enclosure or something. everyone that heard it though it was at least 2 10's.

well, I got industrious and did make some sketches and calculations. It can be found here: [ http://dce.ath.cx/images/enclosure.jpg ].

The image is almost 400 kb, sorry 56k-ers.

The speaker is rated for 2.5 - 5 ft^3, so this seems like it will work pretty well.

Tonight I'm looking for some tips on wiring kits... on ebay I'm seeing deals for 4 gauge wire at about $35 shipped. Do you think I need 4 gauge, and does it matter what brand? How many feet of main wire do people actually use? Some come with 60 amp fuses too, which is like 720 to 800 watts depending on voltage, which is probably enough for this application. Have any of you used circuit breakers with your setup so you don't have to replace a fuse if it blows? I'll bet they aren't much more expensive than a couple of fuses and work related to replacing them.

I hope I'm doing right by asking all these questions in one topic; I figure it saves space on the message board.

60a fuse?
60*13.5=810
that is the power supplies maximum wattage. actual power to the speaker is usually around 60-70% of that. so 480-570w...

so you think I'll need more than that? I can probably get a 75 amp circuit breaker to replace the fuse so I can get the full 1000 watts that amp can draw.

get what the amp needs ;)

If I end up getting a capacitor, that's gonna go after the fuse/circuit breaker, right? How does the current work with that? I've learned some basic electrical stuff, and capacitors can have a fairly large current draw when they're first charging up.

No cap, invest that money in a 2nd auxilary battery. but if you where to install it yes it would be fused before it. you ALWAYS fuse the power wire with in 18" of the battery. this will protect any shorts after that. period. the only itme you refuse is if you usea distribution block and you send say 0awg to the block and 4awg to the wires from post distribution block. unless the power wire to the distribution block is fused low enough to where 4awg can handle the current with out burning. even still it is a good idea to fuse anyway so that instead of all of your amps going out only the one that shorted.

I still can't get over having a sub needing 3-5cu/ft for a box!!!! No wonder I see so many rears of cars dragging. And here I thought they were just hauling fat girls!!!

Dude, you really have never heard a good system have you? 5cuft large? there are thoes who beleive anything under 200l is small...big sound from small enclosures is done with either horible SQ or tons of power.

what he said^^^^ big boxes sealed or porte require less power to get LOUD..... these are usually subs with softer suspensions that are naturally easier to move too.

Does it matter how old the aux battery is? I have an older battery from my Dad's 93 ford ranger that we mistakingly thought was dead, but it turned out the starter had died. We decided to keep the new one because walmart throws so much crap out after people return it. Do you think it will work alright?

Did anyone look at my designs? I'd like to hear some feed back before I try to build this monster.

Thanks guys!

http://dce.ath.cx/images/enclosure_small.jpg

Click here for larger version (http://dce.ath.cx/images/enclosure.jpg)

I have an 8" sub glassed into each door ... most people think there is a 12" sub in the back

what he said^^^^ big boxes sealed or porte require less power to get LOUD..... these are usually subs with softer suspensions that are naturally easier to move too.
Well yes and no. Most other sub makers can have a sub tuned to the same frequency as these you talk about but in a box 1/2 the size. I know it doesn't really matter to you guys. It didn't back when I first started either. Today it does. I don't want a 10cu/ft box when I could have a 3cu/ft box sound as good or better. These subs you guys like requires large boxes because the motor structure is weaker and that is also how they are tuned. They are just a copy off of their home stereo line.

Well yes and no. Most other sub makers can have a sub tuned to the same frequency as these you talk about but in a box 1/2 the size. I know it doesn't really matter to you guys. It didn't back when I first started either. Today it does. I don't want a 10cu/ft box when I could have a 3cu/ft box sound as good or better. These subs you guys like requires large boxes because the motor structure is weaker and that is also how they are tuned. They are just a copy off of their home stereo line.

:grinno: :slap:

Well, I got even more ambitious... I made a CAD model of it :evillol:

[ Wire Frame (http://dce.ath.cx/images/sub%20enclosure.jpg) ]

[ Shaded (http://dce.ath.cx/images/sub%20enclosure%202.jpg) ]

[ Shaded with dimensions (http://dce.ath.cx/images/sub%20enclosure%203.jpg) ]

:feedback:

Well, I got even more ambitious... I made a CAD model of it :evillol:

[ Wire Frame (http://dce.ath.cx/images/sub%20enclosure.jpg) ]

[ Shaded (http://dce.ath.cx/images/sub%20enclosure%202.jpg) ]

[ Shaded with dimensions (http://dce.ath.cx/images/sub%20enclosure%203.jpg) ]

:feedback:
Well, ok. What's those little boxes the tubes are connected to? Those little boxes open? If so, you are messing up the frequency and it probably won't sound good. Also, I usually keep the port inside the box because it just looks better. The only time I don't is if the box is too small or port is too large or if I'm building something strange like a 4th order box with the port going up through the rear deck of a car.

Personally, I'd just go with a sealed box but that's just me.

Well, ok. What's those little boxes the tubes are connected to? Those little boxes open? If so, you are messing up the frequency and it probably won't sound good. Also, I usually keep the port inside the box because it just looks better. The only time I don't is if the box is too small or port is too large or if I'm building something strange like a 4th order box with the port going up through the rear deck of a car.

Personally, I'd just go with a sealed box but that's just me.


It is sealed... I'm just trying to distribute the volume around the inside of the trunk to maximize the usable space in my trunk. I'm planning to make it out of 3/4 MDF with 3" diameter PVC pipes connecting the main chamber to the two smaller chambers. I'd use permanent glue on all but one of each side of the boxes with a silicone seal on the last side so I can open them up easier later. I'd probably use high strength epoxy with some screws embedded in the side of the main box to attach the tubes.

ummm im not seing why you need to do tis, why not make one larger box made to fir around the corners and all in your trunk? these 2 extra chambers conected via a smaller tube may cause some scary dampening factors.

Well, I'd still just go with one big box instead of what you are trying to do. I know you are trying to save some space. You should of thought of that before buying a subwoofer requiring that kind of space.

Well, the bigger center chamber is technically big enough for the sub, I'm just trying to get closer the maximum rating. I can probably just get rid of the side boxes if it really sounds bad, but I'd like to do some tests anyway. If it's really bad, hey, I can just sell them as a premade sealed boxes that someone can put a hole into. Has anyone ever tried anything like this? We can put it down in the history as the first (and probably last) attempt at multiple sealed chamber subwoofer enclosure design. Wow, that was a mouthfull.

Well yes and no. Most other sub makers can have a sub tuned to the same frequency as these you talk about but in a box 1/2 the size. I know it doesn't really matter to you guys. It didn't back when I first started either. Today it does. I don't want a 10cu/ft box when I could have a 3cu/ft box sound as good or better. These subs you guys like requires large boxes because the motor structure is weaker and that is also how they are tuned. They are just a copy off of their home stereo line.

You don't know what your talkin about...... A weak or strong motor structure has nothing to do with box size. Take a look at ohh lets say an XXX it need a hell of a lot bigger box then a brahma, but has a significantly stronger motor. Take some of your beloved directeds (the sx model since its the only one on their site) Let's compare it to RE's SE (12's) since they should be pretty close to each other. The directed has a BL of 25 (bl is motor strength) the SE has a BL of 17.1. And holyshit your precious directed sub needs 3.762 cuft. for a .707 alignment. Yea and the EBP wants it sealed (not that it matters a whole lot) Ported...... well that sub is wierd b/c the graphs of its response are fine at 2.5 cubes ported..... yea I guess you can't seal it....... even though its phtsically better for a sealed box. What a shame.....ok on to the SE........ 1.6 sealed for a .707...... 2 cubes ported...........hmmmm I guess BL has NOTHING to do with box size. BTW about your "HT subs" comment. No RE sub is build for HT...... they're strictly for car use....... brahmas are made for in car use along with kodas (shiva's and tempests were made for HT but work well in home) And Ascendants subs were specifically designed to work in car or in a room.

:(

arguments and debates are getting out of control! lol

here are my pennies:



even though some subs are generally designed for car use, they are usually ok in a Home audio application also. the sub itself does not care what environment it is in. One of the bigger difference between car audio and home audio is the constructions within the woofers. Take say a mid 1990 subwoofer and throw it in the car. chances are, the surrounds are weak and it won't stand up to the car environment as well. You can use an Directed sub in homes just like you can use an RE xxx. i have witnessed the xxx in home when my friend was testing out his 3.5 cubic feet box for his 12" sub. yes it rocks. lol.


secondly, the strength of the motor does have something to do with the box size, but i generally don't really go around saying its very proportional to each other. generally the stronger the motor, the better it will allow you to play in a smaller box. Of course there are always other variables involved.

Last thing before i go off playing with my new toys, when we refer to motor strength that corresponds with box sizes, we are usually referring to the Qes, not the BL, even though the BL is a reference to motor strength. The Qes is a much better indication of motor strength than BL is when it comes to correlating motor strength with box sizes. The lower the Qes, the stronger the motor. Why BL is not the best way to indicate motor strength is because say you have a dual 4ohm in parallel (2ohm) with a peak BL value of 12 N/A. Wire the dual 4 in series and you get 8ohm and your BL also changes to 24 N/A. Despite the value being higher, the actual motor force does not double.


i'm done. sorry if i offended anyone by just coming out and spilling out my jibberish. I didn't read the whole thread though. :(

Well, as long as we're talking technical, here's a chart showing my sub's specs:

http://dce.ath.cx/images/specs.jpg

Mine's the one on the right (the dual 4 Ohm model).

What parts of this are important, and how do I translate it into optimum box size?