Miniature 2" dual opposing subwoofer project using b2-audio-rampage-rc2

[Qrio]

Hi,

My first post!

I'm looking to build a dual opposing subwoofer, like this one-

DB2D - Home Audio Subwoofer | Bowers & Wilkins

DB2D offers more than enough of a punch to excel at home cinema, but is agile and precise enough to bring depth to stereo recordings

www.bowerswilkins.com

Using these new drivers released by B2

2" 4-Ohm B2 Audio Rampage RC2 Subwoofer for RC Cars

Authentic B2 Audio Design – Features a cast aluminum frame, pressed paper cone, and foam surround for high-quality performance and durability. Compact Size for RC Cars – Perfectly scaled for 1/10 RC vehicles, with a 2.24” overall diameter and 2.32” mounting depth for easy installation. 10W RMS...

www.b2audiousa.com

I understand I will never get the bass output of the B&W DB2, it will be more of a challenge to see what is possible. I have never built one
before so need your help and input on my journey. The finished product will sit on my working desk.

I was thinking to have this put in a sealed 30mm acrylic box rather than wood as it's going on my desk. In this way I can see the inner workings in action

What I need-

1) 30mm thick acrylic (would this be thick enough, if I brace the cabinet magnet end for both subwoofers with a circle cut out to support the magnet end. Just
like the DB2 (which has wood to mitigate vibrations).

2) B2-RAMPAGE-RC2 (speakers x 2)

3) Small Amplifier stereo (https://www.amazon.co.uk/dp/B07DJ4N...CALQ1ZFO&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it)

4) 30mm acrylic box I can get built with holes cut out.

Anything missing from above?

Questions

1) Do I need to built a crossover?
2) How do I find out what box size I need?
3) Do I need any dampening material inside the box, like acoustic foam / filling?

Any advice / help appreciated.

 

[voodooless]

Hi there! Welcome to ASR!

I understand I will never get the bass output of the B&W DB2, it will be more of a challenge to see what is possible

What do you expect to get here then? These things have an fs of just below 100 Hz, they won’t produce a lot of bass. The Qts is also quite high, so it will probably have a high peek somewhere around fs.

1) Do I need to built a crossover?

That depends on how you are going to use it. What does the rest of the system look like?

2) How do I find out what box size I need?

Use some simulation software like WinISD pro.

3) Do I need any dampening material inside the box, like acoustic foam / filling?

If you can get it crammed in, sure. Usually it’s beneficial.

 

[DVDdoug]

It's a bit of a stretch calling that a subwoofer.

1) 30mm thick acrylic (would this be thick enough,

It's probably OK but it depends on the overall size. It should be stiff enough that it doesn't resonate. If it needs to be stiffer you can use thicker material or bracing.

1) Do I need to built a crossover?

If there is a tweeter, you at-least need a capacitor in series to block the bass from the tweeter.

2) How do I find out what box size I need?

Plug the Theile-Small parameters into WinISD or other speaker design software. The software will also help you to decide if a sealed or ported box is better.

This is generalization, but a sealed box can usually be smaller, but then it usually needs EQ (and more power) to push-up the deeper bass (whatever "deeper" means with this little thing).

3) Do I need any dampening material inside the box, like acoustic foam / filling?

It "never hurts", but probably not. And if you're using clear acrylic it may look better without it (and a assume that's important to you). Any resonances are related to the wavelengths and internal dimensions. At lower frequencies the wavelengths are long (bigger than the box) so if the speaker isn't also working at higher frequences those short-wavelength resonances won't be excited.


P.S.
A ported box also allows the woofer to move more freely below the resonance frequency and seeing the movement might be visually appealing, even it's not putting-out useful deep bass.