Dave, just because you failed in open baffle, it does not mean its does not work or its a bad approach. I am fond of open baffle, thats what i use in main system. But in my ht system i simply use closed box for simplicity. Open baffle works but there are pros and cons. For some pros outweight cons, for others dont.
If it would not work, there would not be so many commercial offerings. Plus amateur builds here. Just have a look.
https://www.diyaudio.com/community/threads/ultimate-open-baffle-gallery.123512/
https://www.diyaudio.com/community/threads/all-open-baffle.400552/
https://www.linkwitzlab.com/LX521/Description.htm
Of course you can get an enjoyable system with no box.
There are so many compromises in loudspeaker designand so many listeners who hold some things more important than others, that 2 very valid loudspeaker designs can be viewed very differently by 2 different listeners.
OB compromises are something i cannot live with. There is a common factor with all i have listened to, that i could not live with.
dave
In the context of modern DSP capabilities and folks can actually do cardioid at home?……..yes……directivity is a pizza that can be sliced in many ways these days……but what an enclosed space behind a driver, the resonances and reflections?….not so much.
I'm not too sure about that. Also fs exists, as do edge diffractions which could be seen as a form of resonance.
Six 12" drivers will have a radiation area of around 3000cm2, I guess. A single 18" would have around 1250cm2. More is better right? The use of front and rear facing drivers also has the potential for cancellation of even order distortion. I like the Lyngdorf solution.
(Also, the dipole radiation pattern will be maintained higher, because the proportion of radiation area to baffle size is higher.)
(Also, the dipole radiation pattern will be maintained higher, because the proportion of radiation area to baffle size is higher.)
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More drivers, Sd and motor force helps to reduce distortion - yes
Using opposed motion direction with multiple drivers reduces distortion - yes but only microscopically compared to previous
Area proportion shifts dipole null - no
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Baffle width determines dipole range. Location and size of drivers has some effect to dipole peak and null sharpness.
Using opposed motion direction with multiple drivers reduces distortion - yes but only microscopically compared to previous
Area proportion shifts dipole null - no
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Baffle width determines dipole range. Location and size of drivers has some effect to dipole peak and null sharpness.
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Fair enough. But this makes me even more confused about why you said the woofer system is a waste of resources. (Well, looking with a broader view at the global allocation of resources, yes. But then almost everything on this site would qualify as a waste of resources.)
@mayhem13 In post #19 you were singing the praises of your 4 x 12" system, but in post #27 you say a single 18" would be better than the Model B's 6 x 12" system. I don't get it.
@mayhem13 In post #19 you were singing the praises of your 4 x 12" system, but in post #27 you say a single 18" would be better than the Model B's 6 x 12" system. I don't get it.
Here: https://sbacoustics.com/product/12-sb34nrx75-16-norex/
(The are also some Faital 12" woofers that come in 16 ohm versions. Not designed for OB but could be made to work, perhaps.)
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Microscopic?
Here are actual data measured at 10 watts. Please look at 50 Hz. With woofer facing same direction, 2nd harmonic is over 60 dB, 3rd over 70dB (not the same scale as fundamental).
In oposing direction, second graf, 2nd harmonic dropped from 60 to over 50 dB, thats ~10 dB reduction in 2nd harmonic distortion. 3rd dropped from 70 dB to 60 dB.
I would not call 10-20 dB distortion reduction microscopic.
Sorry about the slovak language there, but the picture is the story.
I am sure Dave will disagree, he always says 2nd harmonic reduction is not always a good thing. But to me 10-20 dB reduction in 2nd and 3rd harmonic distortion is a good thing...
Here are actual data measured at 10 watts. Please look at 50 Hz. With woofer facing same direction, 2nd harmonic is over 60 dB, 3rd over 70dB (not the same scale as fundamental).
In oposing direction, second graf, 2nd harmonic dropped from 60 to over 50 dB, thats ~10 dB reduction in 2nd harmonic distortion. 3rd dropped from 70 dB to 60 dB.
I would not call 10-20 dB distortion reduction microscopic.
Sorry about the slovak language there, but the picture is the story.
I am sure Dave will disagree, he always says 2nd harmonic reduction is not always a good thing. But to me 10-20 dB reduction in 2nd and 3rd harmonic distortion is a good thing...
Attachments
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Resources - using four woofers in a wide box vs. Two in a flat baffle. I would like to see comparative measurements of high spl distortion and directivity. The box blocks backside radiation, so effective Sd as dipole is equal to two open back drivers?
Microscopic - I would like to see comparative measurement of the other reversed vs. same diirection. Sorry I can't read the text in the attached paper. I have two 8" woofers available but no time for testing myself in near future
Microscopic - I would like to see comparative measurement of the other reversed vs. same diirection. Sorry I can't read the text in the attached paper. I have two 8" woofers available but no time for testing myself in near future
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For another test of push-pull distortion performance, see here: https://www.diyaudio.com/community/...rmal-distortion-compared.191833/#post-2624898
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I have push-pull OB woofers on my speakers and I have measured 2nd harmonic distortion compensation: https://www.diyaudio.com/community/...78t11-or-4x-purifi-ptt8-0.397228/post-7313301