6th order bandpass design for dual 6.5"

[permo]

The wife has been bugging me to create a more "incognito" subwoofer for the A/V system in auxilliary home theatre/living area. So I purchased a pair of spunky little 6.5 inch drivers from PE for 9 dollars a piece. The specs are here


6-1/2" Subwoofer Speaker
This 6-1/2" subwoofer speaker features a deep profile, long fiber, high-pulp cone finished beautifully in a protective coating that also dampens resonances. The 1-1/2" diameter 4-layer voice coil's 5/8" winding length maintains plenty of copper in the magnetic gap, ensuring plenty of high-impact, low-distortion output. A vented pole piece reduces performance-robbing power compression, and the magnet structure's extended back plate prevents "bottoming out" the long voice coil. Great subwoofer speaker for any design or application, particularly multimedia systems, small home theater setups, and multi-driver configurations. Buyout, limited quantities.
Specifications: *Power handling: 80 watts RMS/160 watts max *VCdia: 1-1/2" *Le: 1.61 mH *Impedance: 4 ohms *Re: 3.25 ohms *Frequency response: 35-2,000 Hz *Fs: 38 Hz *SPL: 83.5 dB 1W/1m *Vas: 0.55 cu. ft. *Qms: 6.74 *Qes: 0.64 *Qts: 0.59 *Xmax: 4.5 mm *Dimensions: Outside diameter: 6-1/2", Cutout diameter: 5-3/4", Depth: 3".

I modeled these drivers together and it looks like a dual chamber, 6th order bandpass design yieilds great results.

.5 cubic foot tuned to 80hz front chamber, 1.5 cubic foot rear chamber tuned to 35hz. Nice 3-4 DB of gain between relatively flat passband of 32-110 hz.

FWIW, she wanted me to purchase bose acoustamas system because it hides so easiy. This is why I decided to build the 6th order with smaller drivers.....to show that I can design and build a better sytem on the cheap.

I will be building my own "cubes" out of Tang Band 3 inch aluminum cone drivers.....

Looking at the specs of these drivers, do you think the 6th order will provide decent sound quality for some non critical listening. I am open to other off the wall designs if anybody has any suggestions.

[ODougbo]

Permo,

I see you missed a project that has been ongoing for a while now, using the PE 6.5 buyout woofer.

Start here, scrole back to about post #50, there are plans, sims, and construction pics.

It is a nice little deal on a driver; a bit on the light side, although my HT never sounded better....using 2 double boxes, 8 woofers.

Isobaric - less then $20

[tb46]

Hi ODougbo,

I think permo is looking for something small. Maybe going with an isobaric 4th order bandpass would do the trick? But, I haven't looked at the numbers yet.

Regards,

[ODougbo]

I'm all ears, I have a few left over..........

[permo]

4th order isobarik bandpass eh....? I will load up winisd tonight and play around with that idea.

Is 6th order iso bandpass just a bad idea? I found with a single driver, the 6th order modeled a whole lot better. I have small mains for this project and I need usable output to 110 hz or so.....

Heck, 4th order iso I bet I could get down to a cubic foot total. That would be SWEET.

[permo]

Here is what I come up with a dual driver 6th order...

[ODougbo]

It looks pretty good in a 1.4cf box with a 10"PR. That would be an easy build and practical, because the rear woofer would be accessible (via the 10" PR).

[tb46]

Hi permo,

Could you, please, post your driver parameter input screen for WinISD. I cannot find a good correlation between what I entered into WinISD and Hornresp.

Hi ODougbo,

What would the equivalent air duct length be to the 10" PR, or , what would the moving mass of the PR be? I have not come up with anything that I would consider workable. Maybe the PE 264-1060:http://www.parts-express.com/pe/show...umber=264-1060

Regards,

[ODougbo]

The 1.2cf Iso test box started off with 2 - 1.5" PCV x 10" vents. From there I went to the 10" PR, 50 grams (but it called for 70grams).

If I remember right, I modeled it with an 8"PR and a 12"PR (PE low cost units); the 10" PR looked the best.

The 10" PR retrofit was the better box.

[tb46]

Hi ODougbo,

Thank you for the additional information.

Regards,