Double Subwoofer Box?

Question

I've decided to try and build a double enclosure for the first time. But the bass is virtually none existant, i know the subs, amps and wiring is all fine, as i had them both in single enclosures, so i'm pretty sure that it's the enclosure i built that's the problem.

I think its because i simply built a box with nothing inside, it is the right size, volume ect. So i'm asking, does it matter that the subwoofers don't have individual compartments within the box?

Regards.

Answer 1

no bass at all, wiring problem.you should hear bass even if the subs are not in an en closer.and i would divide the en closer space evenly.use (rf tech woofer wiring wizard) and use there chart to wire your subs to an ohms load both the subs and amplifier can handle.

Answer 2

The enclosure can't be right if your subs aren't playing bass. Do not switch your leads, yes your subs could be out of phase but switching your leads on the subs will inevitably blow them (make sure they are connected properly). Find the specs of your subs and make sure that they have the right amount of airspace. If the subs call for 2 cubes then (2 cubes for both) the internal volume of the box should be 2 cubes, this is easy for a sealed enclosure. And honestly as long as there are no air leaks, you are close to the recommended specs and the subs are mounted proportionally with the box then it should work okay If you built a ported enclosure then you are in a whole other level. Virtually everyone needs to have a box building program when building a ported enclosure. There are too many variables to account for. I've been an installer for over 10 years and have built several enclosures and I still use programs to build my boxes.

Answer 3

There are advantages to having separate sealed chambers, but a shared chamber will still work fine as long as it's large enough for both subs. If a single sub would require a 1 cubic-foot box, then a shared box for two subs should have 2 cubic feet of volume.



Have you tried switching the positive and negative connections on one of the two subs? It's possible that your problem is caused by the subs playing out of phase.



P.S. Switching the positive and negative leads on a subwoofer will NOT blow the sub, as "Steve" suggests; that's a completely ridiculous statement. Thousands of people make this mistake every week, with no ill effects except for the sound quality. With a single speaker, it really doesn't matter which terminal you use for positive and which for negative; it will work exactly the same either way. The problem occurs when there's more than one speaker, because if they're wired in opposite polarity they'll most likely be playing out of phase, which results in sound waves cancelling each other.

Answer 4

I think you may have a out of phase problem. Double check the sub wires and amp settings again.

Shared compartments shouldnt be a problem. Its been done many times by many reputable companies. There are theoris but as long as the subs are working inphase the difference between shared and isolated compartments is negligible.

Answer 5

The first thing you need to do is look at the T/S Parameters. The 'QTS' figure will best indicate what type of enclosure your subs need. Not that ROT (Rules Of Thumb) are a 'Set in Stone' rules to abide by, however it's generally considered;



qts 0 - 0.4 = ported

qts 0.5 - 0.7 = sealed

qts 0.7+ = IB (Infinate Baffle - free air so-to-speak)



There are many other considerations to take into account including cabin gain (if using a sealed enclosure)



http://www.diymobileaudio.com/forum/technical-advanced-car-audio-discussion/120190-does-anyone-understand-cabin-gain.html = Does Anyone Understand Cabin Gain (Written by Patrick Batemen - PB is one of the most knowledgeable car audio engineers I know of).



Also for a sealed enclosure you need to consider 'QTC'



** Qtc - value for the damping provided for a driver in a sealed enclosure. Denotes the enclosures ability to control the driver response at resonance. Qtc = 0.707 is the optimum value for sealed enclosures, providing flattest response and highest SPL for deep bass extension. Enclosures for this value are often rather large. Lower Qtc can give even better transient response, down to a Qtc of 0.577 for the best damping and transients. ** - http://www.hometheaterforum.com/t/135679/what-does-qtc-mean#post_1526496



http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/25328-qtc-means-what-sealed-double-vented-volume.html#post231855 - Qtc means what? Sealed double vented volume.



** You need PWK **



This is what PWK (HexiBase) does.



http://peteybox.com/design-build/



And this is what he does with a 6.5" subwoofer

http://peteybox.com/hybrid-i6sw/





HexiBase: What’s in my trunk? (paraphrasing)



A 1: 12″ in a perfect box



HexiBase: Size of woofers and how many?



A 2: Two 10′s maybe 600-700 watt range



HexiBase: Single 6.5, getting roughly 90-100 watts at the moment!

Answer 6

What's your port area look like? Tuning?