subwoofer under bed

[Potato42]

Hi all! I recently jumped into DIY audio stuff headfirst, and even as I'm building my first speakers I realize I'm going to need a good sub. I am hoping to utilize otherwise unused space under my bed for a subwoofer so that I might be able to make something of a decent size. The biggest limitation is that I only have 7" in height, though I could make it 5'x5' long and wide. I planned on using 1/2" baltic birch for the cabinet so that leaves 6" of space inside. I was thinking a sealed type enclosure firing upwards (into the bed).

What I'm wondering is how well it might work, and what should I expect? Is it only going to be useful for home theater type rumbles, or might it have the ability to add some depth to music as well? Is this just a really bad idea?

I saw Bjohannesen's "Hideaway sub" which looked like an interesting alternative. I was hoping to keep it all under the bed though.

The speakers I'm building now are Zigmahornet enclosures with the Merrill DCA4 drivers. I'd like for the sub to blend well with the full range drivers. I will be putting these in a small bedroom 10'x10' with hardwood floors.

Suggestions and comments appreciated. I'm completely new to this so any help is good.

[454Casull]

What's the listening position?

[Potato42]

Originally posted by 454Casull
What's the listening position?

On the bed opposite the zigmahornets, or in a chair at the desk next to the bed also opposite but off axis. I didn't imagine listening position would be that important in regards to a sub especially in a small room. Is it a big factor?

[Patrick Bateman]

i did the same thing in my bedroom.

My design is even simpler than yours - it's a 4x8 sheet of wood, with two woofers. That's it!

The woofers aren't centered; they're basically at a point that's 40% of the way towards the middle, instead of 50%.

This is done to even out the response. I even modeled it in Martin King's horn response.

I'm surprised more people don't do this. It's incredibly cheap and easy. I have to confess it plays louder than my tapped horns in my living room. This is because I'm using two very beefy drivers under the bed, while my tapped horns use an 8" woofer.

I hope you give it a try!

Also, I am doing something similar in my TV room right now. I'm building a platform that's 8" tall with SIX subs in it.

[Potato42]

6 subs? That's going to get things shaking! Do you have a picture of the one you made somewhere?

I had a peek at another thread that linked here; http://www.parts-express.com/project...ject=Boogieman

I think I might try a version of it myself with bigger woofers. It's pretty much just what I had in mind. I'll likely use a different amp and better woofers though. This project is likely a little ways off due to financial restrictions at the moment. I need to get the first speakers built up anyway!

[Patrick Bateman]

If you are on a limited budget, keep in mind Hoffman's Iron Law. If you're willing to build a HUGE box, you can get away with a very low power amp. That's one thing that frustrates me when I see all these guys building byzantine horn subwoofers. They can get comprable efficiency from a bandpass, sealed, ported or dipole subwoofer IF it's big enough.

For instance, my 8'x8' subwoofer has an internal volume of about THIRTY TWO cubic feet!

With that kind of volume, I can gain efficiency by using lots and LOTS of subwoofers.

The subs I am using are about $25 a pop. My amplifier is less than $100. The wood is six bucks for a 4'x'8'.

[bjorno]

...I'm surprised more people don't do this...

This is a very old idea; I built my first for more than 40 years ago:

b

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[poynton]

Does the earth move for you ??