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Old 18th February 2007, 07:47 PM   #1
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Default loudspeakers with unknown features

Hello,

Wondering if it is possible to build acceptable quality enclosures for loudspeakers with unknown features:
I mean if diameter, magnet dimensions,power and other "visual" or electrical features could be useful for the purpose.

Alternately, having a good enclosure how to choice suitable loudspeakers (if possible)?

Thanks for any useful feedback

Sincerely
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Old 18th February 2007, 11:55 PM   #2
Ron E is offline Ron E  United States
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That all depends on your definition of acceptable.

Take the advertised diameter of the woofer in cm, square it and divide by 20 - there is your box volume in liters.

17 cm woofer - 17*17/20 = 14.4
21cm ----------- 21*21/20 = 22
25cm ----------- 25*25/20 = 31
30cm ----------- 30*30/20 = 45

If you want a vented box, double this box size and tune to 600/Dia
17cm woofer => 28.8L tuned to 600/17=35

Now try this with some woofers you know the parameters for and see how it works. It works well for some and not so well for others
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Old 19th February 2007, 11:48 AM   #3
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Thanks for your useful post!

What do you mean for vented box? A bass-reflex enclosure?

And, where these calculations come from? Do you have a book, tutorial, or something like that?
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Old 19th February 2007, 05:11 PM   #4
Ron E is offline Ron E  United States
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Just experience, and a bit of a sense of humor. That said, the sealed box recommendation probably won't steer you too wrong.

Still, to get a good design, you should measure the parameters. The rule of thumb I posted is VERY rough and only suitable for cases where you don't know and don't want to go to the trouble of measuring.

Designing a vented box this way is sure to get you in trouble if you were to use a driver with a Q greater than 0.5 or so or with a really low or high resonance. Since many drivers with no parameters are likely to have a Q in the 0.8-1.5 range, I wouldn't generally design a vented box without parameters - so that is the "sense of humor" part.

Even so, try the method out using software simulations on some real drivers for which you know the parameters, you should quickly discover the limitations of such a simple rule.....but I bet you'll find it works fairly well on drivers with "average" (whatever that is) parameters
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Old 19th February 2007, 08:22 PM   #5
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Quote:
Still, to get a good design, you should measure the parameters
That's true. But the question is:

How to perform these measurements?
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Old 19th February 2007, 09:54 PM   #6
Ron E is offline Ron E  United States
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http://www.epanorama.net/documents/a...arameters.html
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Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan
Armaments, universal debt, and planned obsolescence--those are the three pillars of Western prosperity. Aldous Huxley
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Old 20th February 2007, 01:09 AM   #7
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As required, this is the link where wue "speak" about you. There is not only you but some "crazy guys" who build speakers that we don't think about, even in dreams !!!!
The topic is named :"Encore un nid de fous" and the meaning is "Again a nest of "crazys".
Check HERE and enjoy !!!!!

Olivier
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Old 20th February 2007, 10:02 AM   #8
Icelade is offline Icelade  France
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Vous ici, but what are you doing here, shoudn't you be at work
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Old 20th February 2007, 11:06 AM   #9
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Anywhere we go, we meet the same people !!! And i am very interested by his job....
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Old 20th February 2007, 11:13 AM   #10
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Here's another:
http://www.mhsoft.nl/messen_en.asp
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