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Old 28th July 2010, 07:43 PM   #1
CCU is offline CCU  Denmark
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Default Redesigning open baffle sub

Hi fellow diy'er

Im doing some major upgrades and i have build an par of Jamo R909 look a likes and a pair of neeper perfection one look a likes. build both to se what speaker i liked better. but now my old sub look like crap compared.
Therefore i what to redesign my old open H baffle sub, i want to make the sides curved.

My problem is that i can't se what i will be doing to the performance. i can't find any research about it. can you help me guys? What do you think what will happen?

a picture to clarify what i mean
Click the image to open in full size.

hope you can help
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Old 28th July 2010, 07:53 PM   #2
badman is offline badman  United States
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Quote:
Originally Posted by CCU View Post
Hi fellow diy'er


a picture to clarify what i mean
Click the image to open in full size.

hope you can help
In all likelihood you'll get a small boost in the lower lows, and a little less ripple in higher freqs due to reduced standing waves and diffraction.

Take a look at the wraparound on these (they're not vaporware but the side panels have yet to be completed and attached) to get an idea of how to do this nicely. The wider you make the opening the less deep the H-frame needs to be but there are other considerations too.
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Old 29th July 2010, 11:54 AM   #3
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Quote:
Originally Posted by CCU View Post
...
What do you think what will happen?
...
a picture to clarify what i mean
Click the image to open in full size.

hope you can help

My guesses of what will happen:

- The mass reactance of the H-frame lowers.
Decrease in Fs and and rise in Q will be more moderate than
in the "straight" version, if those effects were present there.

- The first unwanted lambda/4 resonance will be shifted noticeably
to a higher frequency, which tends to widen the usable bandwith.

- The flare will cause stronger radiation toward upper bass and
midrange especially above the first quarterwave resonance.

- I can see only very little relative increase in dipole path length,
so i would not expect significantly better low frequency performance.

If all these effects can be dealt with due to driver TSP and the
lowpass filter applied, then it is fine.

If the effects are unwanted, i would prefer to maintain the
curved optics for aesthetics, but keep unflared paths inside.

Nicely formed, cool looking "wedge" in the middle, even rounded at
the "port" ?? Can be made replaceable for test purposes.

Other opinions - as always - welcome !


Kind Regards


P.S. i often thought about making the H-paths a little asymmetric maybe
just 20% to shift the quarterwave resonances between both
paths to make the system more "good natured" at higher frequencies.

Slight asymmetry introduced at low frequency dispersion may be tolerated well ?
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Last edited by LineArray; 29th July 2010 at 12:09 PM.
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Old 31st July 2010, 01:01 PM   #4
CCU is offline CCU  Denmark
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by what you guys are saying, i can only se it as a good thing.
So i must be time to experiment a little.

I'll mayby try making one asymmetrical.

By the way. the image is not drawn in arcurrate ratios.
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