Small subwoofer intended for low profile installation

[Phil Graham]

Our church has a new space with a 21" tall platform. Low profile architectural subwoofers are rather pricey and/or don't offer much extension. So I decided to knock something together for us to use. The driver in question is a 12" from Parts Express and built like a professional driver with 4 layer voice coil, high Bl, low Cms, and three shorting rings.

The following Google drive link includes full BOM, simple DXFs for a millwork shop, all SolidWorks files, PDFs of CAD drawings, and a few pictures of assembly. We assembled five units with Titebond III, 18ga brads, and some strategic clamping.

https://drive.google.com/drive/folders/0BwZr3b_1ro5UTjUxYXFBU3FTUzQ?usp=sharing

I will add frequency response, impedance data, and final processing as I have time to measure a completed unit. For now, you should start with a 2nd order Butterworth HP at 33Hz:

If you have any questions about the design, or any trouble with the link, please respond to the thread.

Cheers,

 

[Don J Davis]

Thank you Phil for so kindly sharing. Look forward to seeing the measurements.

 

[Phil Graham]

Thank you Phil for so kindly sharing. Look forward to seeing the measurements.

Sure, no problem. Nothing magical with this design.

 

[Eric Simna]

Any pictures of the final product in place? This is very interesting for a space I work in.

 

[Phil Graham]

Any pictures of the final product in place? This is very interesting for a space I work in.

Eric, I'll take some tomorrow and add them to Google drive. They're not finished in duratex yet. I actually had people told me the liked the plywood finish, and that we shouldn't finish them in black. Make sure you build them in the good Baltic birch.

Other than a round over bit, the units as assembled are straight out of the flat pack CNC. I'm happy to put you in touch with my cabinet shop, as we already paid the programming fees for the design

 

[Phil Graham]

Any pictures of the final product in place? This is very interesting for a space I work in.

Eric,

Photos of one unit it bare plywood are up on Google drive. I think some is going to prep the cabinets for paint tomorrow. Around new years there should be some finished photos.

 

[Phil Graham]

I will add frequency response, impedance data, and final processing as I have time to measure a completed unit. For now, you should start with a 2nd order Butterworth HP at 33Hz:

I have updated the Google Drive with SMAART and impedance measurements of an enclosure as installed at the church space. Impedance measurements indicate that the port tuning frequency is 29Hz, and thus the HP filter frequency should be 31Hz.

There should also be a parametric at 205Hz to reduce the peak from the slot loading. I have placed a suggested processing document in the Google Drive