Woofer size and dispersion?

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Woofer size and dispersion?

Postby moray james » Wed Feb 16, 2011 11:39 pm

I am kicking around some woofer options for a Klipsch speaker. I have some Klipsch Forte ll speakers. I also have a set of Klipsch Quartet. Both these speakers use the identical mid and hi horns so from 650 Hz. up they are identical. The Quartet seems to integrate a little better or sooner (closer) than the Forte ll do. I am wondering if this has most to do with the woofer's dispersion at crossover to the mid horn. Would any here have polar response measurements that shor the woofers dispersion up to 700 Hz.? Klipsch have done several series of speakers which use dual ten inch woofers but I have hot heard them yet to compare. Any comments regarding woofer dispersion would be most welcome. The K61K mid horn in use in the Forte ll has a dispersion of 90 degrees and runs from 650 Hz. to 6KHz. Thanks for any assistance. Best regards Moray James.
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Re: Woofer size and dispersion?

Postby simon5 » Thu Feb 17, 2011 9:36 pm

Both use same horn, but do they use same driver behind the horn ?

Maybe the crossover design is different too.

Could be a dispersion problem also, but a small woofer at 700 Hz doesn't have much problems usually.
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Re: Woofer size and dispersion?

Postby moray james » Sat Feb 19, 2011 4:34 pm

Thank you Simon: the Forte ll and the Quartet use the same horns and compression drivers. My question was really as to what size woofer (a ten or a twelve) would have a closer dispersion match to the K61K mid horn at crossover of 650 Hz, which for the horn is stated as 90 degrees. I am wanting to upgrade the woofer to a higher efficiency AE driver but need to decide if I should go with a ten or a twelve inch driver. I had thought that twin tens might be a good way to go but would also like to have the output as high as possible. I am not 100% clear as to the difference between efficiency and sensitivity either so there is some confusion about that also. It is my impression the dual woofer designs by Klipsch while rated as similar efficiency seem to require more power to drive than do the single woofer designs of similar stated efficiency. This may have to do with the difference between efficiency and sensitivity.
The K61K has a base efficiency of 105 db and it would be interesting to know what woofers (probably a quad) could keep up to that as it would be nice to run the mid wide open with woofers which could keep up, there are many suitable tweeters which could match the mid. For right now I am most interested in finding a woofer size which can mate to the mid horn while matching the dispersion of the horn at crossover. Thanks for your assistance regarding this. Best regards Moray James.
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Re: Woofer size and dispersion?

Postby simon5 » Tue Feb 22, 2011 9:38 pm

At 650 Hz, both TD10 or TD12 are nearly omnidirectional, since the wavelength at 650 Hz is about 20 inches long, which is nearly twice the size of both woofers diameter. I wouldn't worry with either choice.

If you choose your impedance well, two 10s will take the same power and play roughly as loud as a single 12 of the same model (they will have similar efficiency/sensivity).

If your horn is really 105 dB/W/m, then you would need quad TD15M... a bit overkill if you ask me. Better to go active with separate amplifiers... especially because each TD15M can tolerate over 500W RMS, and your compression driver will blow up well before you reach that number.
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