Thread: Audio Mags - Speaker Box Design Question

I know there's a few of you out there...

I have a pair of 10" subwoofers that I want to build enclosures for.

The paperwork from the manufacturer says these speakers are recommended for use in vented enclosures with a volume of 1.0 - 1.5 cu. ft, with 1.25 being optimum. It also says to use a 3" x 5.25" vent.

Just for kicks, I plugged the Thiele-Small parameters into several online calculators and they all came up with much larger enclosures than that, anywhere from 2.15 - 2.97 cu ft. with different vent specs. These calculators also indicate these speakers are equally suited for use in either sealed or vented enclosures.

What gives? I'm wondering if there's a mistake in the manufacturer's brochure as it covers mutliple speaker models. There is a different 10" model that is recommended for sealed enclosures that lists the same volume specs. Did someone accidentally copy the sealed enclosure specs into the vented enclosure column?

In case you're curious, the relevant specs are:

Vas = 2.88 cu. ft
Fs = 32.4
Qes = .440
Qts = .407

Any insight appreciated.

Are you sure mfg specs aren't for a single speaker, and the online specs for 2? That's what it sounds like to me.

Thanks, but these calculators do not have any options for number of drivers, so it's logical to conclude they are for single drivers.

http://www.diyaudioandvideo.com/Calculator/Box/

http://www.ajdesigner.com/fl_subwoofer/subwoofer.php

I know there are some people into this stuff around here, I'm guessing they haven't seen this.

What brand of speaker?

One would like to think the manufacturer did thier research.

There are a few other parameters, such as X max. Join here:
Www.Diyma and/ or www.caraudioclassifieds.org, lots of free plans and advice.

Try one of these http://www.hometheaterhifi.com/volum...tember-99.html

For shits and giggles, you could just build a couple of quicky enclosures in different sizes to see what it sounds like. I would think that just a simple plywood box would give you the basic sound characteristics.

Not remotely true, Toast. One tiny bit off and a great subwoofer can sound terrible. And vice versa.
CW, what subs are you running? I am currently looking for a design for two Sundown SA 8's ( v 1.5) for under my rear seat, it is a super- bitch, apparently.

Originally Posted by AaronWright

Try one of these http://www.hometheaterhifi.com/volum...tember-99.html

resonant frequency at 20hz, with a 'near field' db of 120db?


That's some weak ass amateur crap. That would sound like dogs shit in a vehicle, IMO.

Originally Posted by capulin overdrive

What brand of speaker?

One would like to think the manufacturer did thier research.

I'm inclined to believe their specs but was curious what the collective would have to say about why the online calculators I found are giving different enclosure volumes.

The speakers are old Kicker competition series drivers. Manufactured in 2000 and have been sitting unused in their original boxes in a closet all this time. I just want to use them out in my garage and have a bunch of HDPB laying around that I could use to whip up some boxes.

For any 'local' viewers of this thread, I have three custom built 12" boxes Fi need to get rid of.. One is huge (3cube ported), one 2 c ported, and one sealed. All extremely well built. Could even deliver to SLC

Originally Posted by rideit

Not remotely true, Toast. One tiny bit off and a great subwoofer can sound terrible. And vice versa.

If they can't be even a tiny bit off, then how come both the online calculators and the manufacturer's specs give a range of sizes that will work?

Not to hijack, but if anyone wants I've got an old factory built Rockford Fosgate set up I'd be willing to off for super cheap. 2 12" subs, 2 horns, and if memory serves 4 tweets. It needs some new mounting brackets for the metal sub covers, but otherwise works perfectly. Think I paid $600 about 15 years ago, but it's just taking up space in my garage. $40 or a decent bottle of whiskey? It's in N. Tahoe, but I could bring it back up to Portland if anyone's interested.

It's not just the spaces, but the overall design. The orientation of the ports, interior baffles, and even whether the interior corners are straight 45 degrees, or beveled, can make pretty immediate differences in resonant frequency, development/ management of standing waves, and frequency/ intensity of 'cabin gain' within both the sub box AND the intended vehicle. Even material choice and internal bracing can change the damping and suspension characteristics of the sub in question, coloring the sound at certain frequencies and amplitudes. Some of this is fairly esoteric ( and likely not that relevant for CW's purposes), but in my applications, pretty immediately noticeable.
Yes, I am bit of a car sound nerd, got rebitten by the bug hard in the last few years.
Think of it like skis. One tiny change, and an otherwise identical ski can ski quite differently to someone very familiar with the dynamics of the ski. Not so much to a casual weekender on rental gear.