Pendulum H-Frame Woofer - diyAudio
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Old 8th August 2011, 10:40 PM   #1
OllBoll is offline OllBoll  Sweden
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Default Pendulum H-Frame Woofer

I've thought some about open baffle woofers, the most recent one is a single driver 15'' H-frame woofer to handle up to 200-300 hz. The preliminary driver is the Dipole15.

I wish to eliminate vibration though... so the idea is to suspend the speaker cone like a pendulum on a square baffle inside a H-frame:

Click the image to open in full size.

The big question now is would would work well as a normal H-frame? Would the small gap at the bottom and sides be a problem or is it negligible?

I thought about suspending without the surrounding H-frame but according to Rudolf's nice PDF (no-baffle simulations in the end) would simply waste SPL, which if true I'd rather not do

// Olle
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Old 9th August 2011, 12:00 AM   #2
bbggg is offline bbggg  United States
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Think Newton's Third Law. A suspended woofer frame will recoil just as guns recoil when they fire. This is called dynamic compression. And if your hinge does not behave linearly with frequency, you will also have added distortion. In other words, the woofer maker's endeavors to linearize its spider and surround behavior will have gone to waste. You had best think of other solutions, like making the frame heavier, using a W-frame with two horizontal drivers, anchoring the frame to the floor, etc.
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Old 9th August 2011, 12:07 AM   #3
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How about this.
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Old 9th August 2011, 02:24 AM   #4
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The last idea is something to try, maybe you can found some rubber with a kind of "X" profile, normally intended to car doors.

The general idea of decoupling is nor bad too, because there is a real problem. For years I had H frames with 15", EQ flat till 25Hz. At these frequencies, they were emitting a noise that was "obviously" aerodynamic perturbations caused by the basket. Long time after, I discovered that this noise was simply suppressed with thick rubber pads under the cabinets (heavy ones, close to 40 kg). BIG surprise !

This means also that just decoupling the cabinet can be enough and far easier.
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Old 9th August 2011, 02:33 AM   #5
OllBoll is offline OllBoll  Sweden
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Hmm, interesting.

Since eliminating vibration of an H-frame without losing SQ seems to be as reachable as utopia I'm instead leaning towards the classic Phoenix W-frame instead.

Thanks for the input!
// Olle
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