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Multi-Way Conventional loudspeakers with crossovers

Acoustics of corners
Acoustics of corners
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Old 12th February 2018, 10:43 PM   #181
torgeirs is offline torgeirs  Norway
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http://www.swissaes.org/nl/aes_newsletter_135.pdf
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Old 12th February 2018, 11:01 PM   #182
torgeirs is offline torgeirs  Norway
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Experimental assessment of low-frequency electroacoustic absorbers for room modal... | Request PDF
I requested the article and got it. (Not AES member)
Looks like they also try other methods. Look at the article indexes of the authors.
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Old 12th February 2018, 11:06 PM   #183
scottjoplin is offline scottjoplin  Wales
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Nice one, thanks! Plenty there to keep me out of mischief
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Old 13th February 2018, 12:08 AM   #184
gedlee is offline gedlee  United States
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Torgeirs

Reading carefully, the "passive" paper has mixed results. It uses four large drivers, in a very small room with virtually no damping. So this is clearly a "best case" scenario. The measured results are taken very close to one of the dampers - not really fair. The global loss in one case was about 2 dB - in a very reverberate space - or about 1/2 dB per source. This isn't really very appealing.

Now active I would expect to be very effective if done right. That might be appealing, but not so low cost. I suppose in European rooms this might be appealing, but here, not so much.
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Old 13th February 2018, 01:04 PM   #185
torgeirs is offline torgeirs  Norway
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Yes, seems like small rooms with concrete/hard walls. And room dimentions creating problems/booming in the 70 to 100 hz region is best suited.
But, if that is the case, it may bee a cheap help both on noise and sound quality

Even if over all noise is not much dampened because of small bandwith. This is a region that is very annoying and not very well masked by other sound sources

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Old 14th February 2018, 07:48 PM   #186
Antoinel is offline Antoinel  United States
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Acoustics of corners
Quote:
Originally Posted by jlo View Post
Back to my first question :
I think that found one explanation after a nice discussion with somebody who was active in the development of the AVAA from PSI : this active absorber is a nice tool to understand some acoustics because you can easily compare and measure when switching it on/off.
My explanation : when you place this absorber or a passive resonator or absorbant in a corner (ie anything that has some acoustic inluence in low frequencies), this "absorber" can be considered as a re-radiating item. Generally its dimensions are smaller than the low frequencies wavelengths concerned. Due to the small dimensions, the directivity of the re-radiation is wide and so will influence and distord the original soundfield everywhere in the room.
Does this make sense ?
Hello jlo. The active absorber by psiaudio reminds me of that described by Nelson S. Pass [inventor] in his US patent 4,899,387. Are you aware of recent and pertinent patents by psiaudio; because they have to build upon the Pass patent?. I experimented with such absorbers. They remove bass energy out of the room. Readily discernible.

I sit in a room corner [acoustically filthy] and listen sequentially to the active absorber enabled and not. Its cleaning performance is readily discerned. Consider using the song for this test called Water under the bridge by Adele 25.

Any active absorber must not radiate energy back into the room as gedlee has already replied.

Thanks to the authors/participants of this interesting and educating thread.
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Old 18th February 2018, 12:26 AM   #187
WBS is offline WBS  United States
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Acoustics of corners
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Originally Posted by AllenB View Post
Another way to ask your question might be: can I equalise the bass to my listening position and ignore the modes..
The answer is, "yes" according to a detailed study undertaken by Todd Welti for Harman Int'l. One of the low frequency optimization goals was "Get lots of output, with flat frequency response over a defined listening area."

It seems to me that strategic placement of 2 or 4 woofers is much more practical for the average diyer than spending thousands of dollars acoustically isolating an extra layer of wallboard then taping and painting 2 opposing walls, especially if the result is close, equal to or better than the wall upgrade.

As a matter of fact, that option isn't even available to audiophiles like myself who have windows and sliding glass door along one side of the room, and no back wall because the room opens into the kitchen.

The first time I heard about this theory was reading about The Swarm Subwoofer System sold by Duke LeJune of Audio Kinesis.
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Old 21st February 2018, 09:47 AM   #188
DorinD is offline DorinD  Romania
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As an update from my part (mostly regarding usage of electroacoustic absorbers), I went beyond using only one method to get good bass in my room. I supplemented the existing two big Hofa's (functional bass trap type) with two EQ Acoustics panels (membrane bass trap type) and increase the number of multiple subwoofers from two to five. The improvement is so substantial that I can call for armistice and will resist spending more on either acoustic treatment or subwoofers because I want my room looks like a home, not a recording studio.
I tested all the hard bass tracks I knew or recommended by others and on neither one I found any trace of "instability", all sounded as they should (I'll come back with a waterfall I did on that occasion).
Regarding the effect of a passive electroacoustic absorber, I observed that it is so diminished after I increased the number of usual bass traps and subwoofers. To the level it becomes indiscernible. As long as my room was untreated it was quite discernible, not the case now.
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Last edited by DorinD; 21st February 2018 at 09:51 AM.
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Old 21st February 2018, 10:49 AM   #189
torgeirs is offline torgeirs  Norway
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Thanks for the update and summary. Nice to know.
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Old 21st February 2018, 06:09 PM   #190
scottjoplin is offline scottjoplin  Wales
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Quote:
Originally Posted by DorinD View Post
increase the number of multiple subwoofers from two to five.
How have you arranged them, mono, I presume, and have you EQd them?
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