12 inch woofer dispersion pattern

[krzys]

Guys measuring spatial dispersion of a woofer is very hard task in home environment . Is there any any mathematical way or even a rule of thumb to know the dispersion pattern of a woofer vs the frequency? Specifically I'm looking for information for a 12 inch woofer like the Altec 414.
Chris

[aditya]

Hi...

Yes, you are right about the measurment process in the home environment.
And also..... yes, there are generic datas available.

But the fact is that the mesurments truly hold ground when, only when, they are measured at the site that they are going to be used, ie., your home ...!

If you google....you will find many free softwares ready to do the job. Actually there are many.

Ofcourse you will need a microphone and a computer with a sound card.....but it is not a headache. A Panasonic W60/61 will do the job, and any of today's PC setups will suffice. It will be a good learning curve if you want to keep at it. Otherwise depending on generic reports will definitely make one reach the right ball park but without any predictability.

Aditya

[bfish]

Hi Chris,

Here's Altec's published method;

http://alteclansingunofficial.nlenet...ers/TL_237.pdf

[nullspace]

Here are measurements of some 12" drivers, including the GPA 414: DriverVault.

I think, generically, 12" drivers are ~6db down @ 45deg off-axis @ ~1400Hz if I I recall correctly -- or that's the 'book' value, anyway. Though, as others have stated, it's no substitute for measuring them yourself. I've found that I can get pretty decent measurements in my small-ish room up to 35deg off-axis down to about 500hz, which is good enough for crossover designs for anything I'd consider building.

Regards,
John