loudspeakers with unknown features

mastermosfet · 18th February 2007, 07:47 PM

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

Ron E · 18th February 2007, 11:55 PM

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

mastermosfet · 19th February 2007, 11:48 AM

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?

Ron E · 19th February 2007, 05:11 PM

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

mastermosfet · 19th February 2007, 08:22 PM

Quote:

Still, to get a good design, you should measure the parameters

That's true. But the question is:

How to perform these measurements?

Ron E · 19th February 2007, 09:54 PM

http://www.epanorama.net/documents/a...arameters.html

breizheau · 20th February 2007, 01:09 AM

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

Icelade · 20th February 2007, 10:02 AM

Vous ici, but what are you doing here, shoudn't you be at work

breizheau · 20th February 2007, 11:06 AM

Anywhere we go, we meet the same people !!! And i am very interested by his job....

Geek · 20th February 2007, 11:13 AM

Here's another:
http://www.mhsoft.nl/messen_en.asp

18th February 2007, 07:47 PM	#1
mastermosfet diyAudio Member Join Date: Feb 2007 Location: Italy	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

18th February 2007, 11:55 PM	#2
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	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 - 1717/20 = 14.4 21cm ----------- 2121/20 = 22 25cm ----------- 2525/20 = 31 30cm ----------- 3030/20 = 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 __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

19th February 2007, 05:11 PM	#4
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	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 __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

19th February 2007, 09:54 PM	#6
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	http://www.epanorama.net/documents/a...arameters.html __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

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19th February 2007, 11:48 AM	#3
mastermosfet diyAudio Member Join Date: Feb 2007 Location: Italy	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?

20th February 2007, 01:09 AM	#7
breizheau diyAudio Member Join Date: Aug 2006 Location: 42 - ROANNE	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

20th February 2007, 10:02 AM	#8
Icelade diyAudio Member Join Date: Oct 2006	Vous ici, but what are you doing here, shoudn't you be at work

20th February 2007, 11:06 AM	#9
breizheau diyAudio Member Join Date: Aug 2006 Location: 42 - ROANNE	Anywhere we go, we meet the same people !!! And i am very interested by his job....

20th February 2007, 11:13 AM	#10
Geek diyAudio Member Join Date: Sep 2004	Here's another: http://www.mhsoft.nl/messen_en.asp

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