Omnipole vs Bipole ?

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soundaatma

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#1
Having made dipoles I have come to like the ambient sound which sounds more natural in nearfield listening in moderate sized rooms. The dipoles can only be shrunk so much though.

So perhaps a omnipole or bipole can be as good in providing the same ambient effect in a smaller package than a dipole. Indeed SL also compares the Pluto very favourably to the Orion for the ambience at closer listening distances. Unfortunately omnipoles need very small drivers and narrow to non-existent baffles to be omnipolar, thus limiting high SPL applications. Also simple omnipoles like the Pluto have omnipolar radiation to about 2000 hz only.

So it seems that bipoles would be the best solution for an ambient soundfield with good dispersion to more than 15KHz, at high SPL in a smaller than dipole package. Does anyone have experience with comparing omnis to bipoles ? Thanks.🙂
 
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#5
dewardh said:
Why do you want "high SPL" in "moderate sized rooms"?

PLUTO is effectively omnipolar to something closer to 4kHz . . . it is not like there's some "brick wall" at 2000 hz where the pattern abruptly changes. And, should you feel the need, you could always add a "rear tweeter" to PLUTO. You might also consider this:

Trevor Marshall - Ground Effect Omnidirectional HiFi Loudspeakers
Click to expand...

Thanks for the link dewardh 🙂
However I really doubt if Trevor is having HF omni radiation from this driver Peerless Tymphany 830893 as its polar response becomes quite narrow after 4KHz and pointing it upwards will likely have no focus of the auditory image😕

Actually I am not after higher SPL but rather lower extension which would also mean more displacement than a 5" woofer could manage. without running out of xmax 😱
 
#6
planet10 said:
Most bipoles will be closer to omnipoles than Pluto.

dave
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Yes Dave, I too have the same suspicion 😉
at least based on theoretical reasoning. Just wanted to have somebody support my ideas with practical experience 😛 while I continue to experiment 😀 with wider than deeper bipoles.

Only thing bothering me is the inevitable edge diffraction effects on a wide baffled bipole compared to a minimal baffled omnipole like the Pluto.
 
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#10
soundaatma said:
Thanks for the link dewardh 🙂
However I really doubt if Trevor is having HF omni radiation from this driver Peerless Tymphany 830893 as its polar response becomes quite narrow after 4KHz
Click to expand...
Actually it stays quite broad well above 4kHz, and used with the placement as Trevor uses it (at floor level) one could easily stay in the "omni cone" to well above that frequency. I haven't duplicated his specific design, but I have experimented with that driver, and even in a box (on a baffle) its dispersion is surprisingly broad. One of the problems with "bipole" (apart from the beaming from generally larger drivers) is that because of diffraction related to box geometry you do not get the desired smooth (omni) summation off axis.

soundaatma said:
Actually I am not after higher SPL but rather lower extension which would also mean more displacement than a 5" woofer could manage. without running out of xmax 😱
Click to expand...
That's going to be true of anything, "bipole" included. The L16RN-SL has a lot more linear stroke than most (even a pair of) drivers its size, and by design its surface area is more comparable to 7" or even 8" drivers. That translates to more bass capability (and extension) than a quick glance would suggest. If you want lower add a sub . . . they are all "omni" anyway. I've heard PLUTO demonstrated in rather large (25x40 ft.) rooms, and bass was not an issue (at reasonable listening levels and "acoustic" source material). As far as the polar goes there is absolutely no "sweet spot", and the "sweet area" covers very close to all the room. And again, if your tastes run to bulging the car windows you're going to want a sub regardless.
 
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