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Old 2nd October 2012, 10:45 PM   #271
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What is it with cats and speakers? Mine love the ports on my Altecs. They love to reach in and pull out the fiberglass.
Yes the bond between cats and speakers is special, its propably ancient as cats got built in speakers, thats how they can do that purrr sound with the mouth shut.

Click the image to open in full size.

The thing with pulling out stuffing we handled by appointing her general manager over internal architecturals and damping distribution.


Click the image to open in full size.
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Old 3rd October 2012, 03:57 AM   #272
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Simple WinISD sim of Beyma 21L50 estimates 97.5 db/watt that is 3db down at 30Hz in a LARGE 16-17 cuft ported cabinet.

For comparison, my Lambda TD15S are about 93.5 db/watt with -3db down at 25Hz in a 11 cuft ported cabinet.

The Geddes multi-woofer strategy to reduce room bass modes is another form of building LARGE. Sealed box woofers with digital room equalization is often used in the Geddes strategy. The natural -6db/octave of a sealed box is closer to the room gain than the -12db/octave of a ported box woofer, and this match simplifies equalization.
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Old 3rd October 2012, 04:02 AM   #273
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Originally Posted by LineSource View Post
The natural -6db/octave of a sealed box is closer to the room gain than the -12db/octave of a ported box woofer, and this match simplifies equalization.
That should be 12 and 24dB/oct respectively.
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Old 3rd October 2012, 08:04 AM   #274
palmas is offline palmas  Portugal
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Ingvar, although I'm not commenting your posts I'm following all details from that huge project.

"Mind You! In normal domestic conditions they need adaptive active bass controll"

Why is that? too much bass? small room?
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Old 3rd October 2012, 10:46 AM   #275
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Default In search of something REALLY BIG

Morning one and all.

The original design of this thread has faded to nought due to my less than realistic ideas of what is achievable within my budgets.

I've appreciated your comments, info & pics, but the the thread seems to be wandering a little Seems we all like our boxes BIG around here and their gravity is pulling us off course


However, I would like to continue with a second line of inquiry into the 'REALLY BIG' by way of:- Horn & big box 2-way

The Onken - much lauded by Pano among many others
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Originally Posted by Pano View Post
Thanks for the parameters! That helps. 12 ft^3 is big and gives you lots of room to work.
Since you need to be near the wall, that leaves out Open Baffle.

Lot's of good designs and approaches to pick from. Given that size, I might go with a full size Onken (15") or the Petit Onken (12"). Just one of many good designs to choose from.
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Originally Posted by Pano View Post
I'll dig up the Onken specs when I get home, if you don't find them first. Search for 360 L Onken. I like the big Onken with the Altec 416 very much. It's very tight bass, never boomy. It can tickle you like a feather, or smack you in the face. Yes, it does very well at low levels - that's one of its strong points.

The Petit Onken doesn't dive up much to its bigger brother for a much more reasonable box size.
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Originally Posted by Pano View Post
But the enclosure can be adapted to other drivers. The "Petit" uses the Altec 414, IIRC.

Most of us are not used to a speaker with out overhang, resonances, slop, doubling. It can sound too clean for some tastes. Not the "clean bass" that comes from no fundamental/all harmonics, but clean from not having slop.

You'll find lots of photos on the interweb, take a look to see if you like its style or not. I think it's an impressive looking, as well as sounding cabinet.

Oh, I just remembered! Kevin, one of the mods, has a set of Onkens he dearly loves. I don't recall what driver he uses. We should ask.
I've found plenty of threads where people are trying them with non Altec drivers, some with success. I am struggling to identify what constitutes a good driver for the Onken. I can merrily punch T/S numbers into the Excel calculator but cant interpret the answer!

Is it worth trying to bend the Onken to a new driver or would I be better just design a suitable box for the driver?

Maybe this thread should have been called - 'In Search of Something REALLY BIG'
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Old 3rd October 2012, 10:47 AM   #276
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Originally Posted by palmas View Post
Ingvar, although I'm not commenting your posts I'm following all details from that huge project.

"Mind You! In normal domestic conditions they need adaptive active bass controll"

Why is that? too much bass? small room?
No, just a stupid old mans silly humour, refering to the cat in the port.
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Old 3rd October 2012, 08:09 PM   #277
Pano is offline Pano  United States
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Is it worth trying to bend the Onken to a new driver or would I be better just design a suitable box for the driver?
That, sir, is a very good question! Reading a lot about the Onken seems to show that it is basically a BR box. Port tuning is the hard part, as it's part of the box. Of course you can stuff the ports.

Forum members KevinK and GM should be able to tell you more about non-Altec drivers in the Onken alignment. Jensen Ultraflex is the original design.

FWIW, I've never gotten the Onken Calc spreadsheet to give me numbers that make sense.
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Old 3rd October 2012, 08:28 PM   #278
sippy is offline sippy  United Kingdom
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Port tuning is the hard part, as it's part of the box
I know how...... and I, he who knows not how to design a loudspeaker enclosure, posted pictures.
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Old 3rd October 2012, 08:28 PM   #279
tinitus is offline tinitus  Europe
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if I remember correctly, woofers with big Vas and lowish Qts

wasnt the original Onken a huge 500liter thing
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Old 3rd October 2012, 08:29 PM   #280
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Only applies to port/ vent Length though.
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