diy stereo subwoofers

[basket weaver]

I'm interested in adding a pair of sub woofers running in stereo to my system.
Just wondered if anyone knows if the Q Acoustics 3070 sub (which has 2 drivers) runs as double mono or stereo.
As I do a bit of cabinet making, building a couple of separate cabinets and splitting the drivers would be cost effective and a bit of fun.
Phil

[rewfew]

I would venture to say that subwoofer is a single source regardless of two woofers in the box. Intended for higher output and spl's. Still a mono source. Your stereo sub approach is desirable. This approach with two, three and even 4 subwoofers is known to smooth out room nodes that cancel varying frequencies. Having at least two subs can allow for the nulls to be filled in by the other sub. Here's some technical information if your interested to wrap your head around it.
https://audioroundtable.com/forum/index ... #msg_66914

[theclosetguy]

Designing a sub woofer is more than just taking a driver and sticking it into a box. A quick Google search of the Q Acoustics 3070 shows a 2 driver ported single box unit. It's an active speaker with so-so spec's. This does not go very deep. 50HZ's is standard Woofer range. The use of 2 6" drivers and a port should bring a better system downing to the low 30's . I doubt this unit has 2 amplifiers also. Usually the left and right signals are summed and feed into the 1 driver. I'd be looking for something that can get down 20hz if you want to add some rumble to the mix. Sub-150hz is pretty much non-directional so mono/stereo really does not matter. Front firing will through it forward, bottom firing will spread it out. Front firing with a rear port will play with the walls. A 30hz wave is about 26ft long. Floor firing helps to spread this out.
Parts Express, Madsound are the best places to find drivers that will fit your needs without paying for a box. Also ApexJr sells sub woofer plate amps and sub's for cheap that are way better than this units amp and much more power.
When I started building boxes 45years ago using cones from an existing system was a start. You soon graduate into buying drivers and components. Sometimes you get lucky and find a 60's-70's quality box at a thrift store for really cheap and than pirate the drivers.

Mike M

[theclosetguy]

the idea of a powered system and dual drivers is to make up for cone size. My current set of woofer's are 10" long throw Sea's in a ported box and they do get to 30hz or so. The box is big however. 18" x 23 x 30" and non-powered, part of a 3 way system.
There a few DIY sub-woofer web sites. Check them out for plans and advice.

[rewfew]

A stereo subwoofer is kind of a misnomer. Just a vestige of having dual, (and or more) subs present. They're mono sources regardless. The multi sub approach is as the link I provided, a means to even out the room subwoofer(s) response.

[basket weaver]

Thanks for all the replies. I had a read of the 'audioroundtable' article. Does this mean the human ear can detect the imbalance of low frequencies due to objects in the room that reduce the energy level ie volume but not the frequency?
My initial reason for going for stereo rather than Mono was that little mono switch on my amp. When I switch to Mono, I notice a significant loss of music detail. So I assumed stereo subs would be better than mono.
Clearly I'm in deep water with building my own. So I'll look out for a couple of half decent readymades.
Thanks again
phil

[theclosetguy]

Phil
taking a stereo signal and then turning it into mono will definitely change how it sounds. The mono switch on your amp is to allow a mono signal to be feed into the 2 speakers.
Don't give up on the build, Buy a kit from Madsound or Parts express. Its fun.
Mike M

[rewfew]

Does this mean the human ear can detect the imbalance of low frequencies due to objects in the room that reduce the energy level ie volume but not the frequency?

Not just objects, but the room itself and the reverberant energy created by the subwoofer. Frequency's can be cancelled out and diminished. Why a single subwoofer can sound boomy. Here's another link I found that has a bit of visuals to help with all the technical jargon. https://forum.blu-ray.com/showthread.php?t=48286
Like closetguy says, there are a multitude of sub kits, that come with the enclosure, plate amp etc. that result in a probably higher quality investment for the money than a ready made.

[JoeE SP9]

For a very good and easy to make subwoofer check out the Pass Labs DIY site. I use two scaled down for 12" woofers.

https://www.passdiy.com/project/speaker ... -el-pipe-o

[hobie1dog]

There's no replacement for displacement you need cone surface area and the more the better so definitely look into 2 at least 12 in if not 15 inch drivers I would suggest going to the stereointegrity website and look at their subwoofer drivers.