My twin ten inch sub does not work.

[tade]

Specifications:*Power handling: 110 watts RMS/220 watts max *Voice coil diameter: 1-1/2" *Le: .5 mH *Re: 7.1 ohms *Frequency response: 40-2,200 Hz *Magnet weight: 20 oz. *Fs: 41 Hz *SPL: 86.4 dB 1W/1m *Vas: 2.19 cu. ft. *Qms: 4.46 *Qes: 1.60 *Qts: 1.19 *Xmax: 3.5mm

There is some specs. I put these two in a 40 liter box with a port of dimentions .5 inch by eleven inch by 22 inches, and had planned on a port tuning of twenty hz. i used WinISD to help me but other than that, just dove in.
I expected there to be much air movement out of the port at its load frequency, but there i very little. And very little at any other frequency. The port end is about two inches off of the back wall.

Please ask me any other questions so that i may be more specific, my H baffles have more bass!

Many thanks

[ocool_15]

If you want to make more air move you can increase the tuning frequency and risk port noise.... They only have a 3.5mm xmax so im not sure how much air your expecting to move....

[simon5]

These drivers are not designed to play 20 Hz efficiently.

Try tuning them higher by shortening the port.
Try 11 inches long, then 5.5 inches long if not enough bass again.

It will be less than good, but you'll have more bass that 100% sure.

[tade]

excellent, this is just the advice i was hoping for. The port is another piece of wood close to the bottom. I suppose i will just drill some holes in it.
As to how much air? hmm, I figured more than a bit because of the large surface area.
thanks

Let me do a little epxperimenting and ill come back with results.

[simon5]

Would be better to remove the piece of wood, cut to the required length and replace. But do what you have to do hehe!

You could also put a bigger port or a second one, that would do the same effect as using a shorter port.

[boydon_lepasci]

If I've read this correctly, you have a ratio on your port of 22:1? I have always heard that the maximum should be 7:1 because unpredictable port action can occur beyond that. Anybody have real-world experience with this?

[tade]

do you mean width to height? I had thought about this, the high surface area of the port may lead to undue friction.

I believe i may have real life experience with this...

I plan on shortening the port to eleven inches and giving that a listen.

[planet10]

With a Qts of 1.19 these should not work at all in a ported box. The Q is indicative of an open baffle, but a big aperiodic box would likely be better given th elimited excursion.

dave

[boydon_lepasci]

Yes, the ratio I was referring to is height and width. Your surface area would not change by keeping within the 7:1 geometry. It would though if you used multiple ports to get a desired total area. I'm still waiting for further opinion on the ratio issue in non-circular ports. Anyone...?

[tade]

Guys, i did some drilling and it is now tuned to about 27 hz, up from 18. Now it works and it sounds about as great as a fourty dollar sub should! i am quite happy, and not at all worried about blowing out the thirty dollars worth of drivers. Ill post pics, but only for a laugh, I really shouldnt be proud about this project...

Thanks for the help guys!
Thaddeus