posted
I would like to know how to find the Qtc for my self but I will give you the info. 8" OEM Woofer fs 60, SPL 94, vas .80 cuft, qms 3.69, qes 1.29, qts 0.95, xmax 3.5mm There are 4 of them total That is all the info I have. Thanx Duk
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[This message has been edited by Rafmeer (edited 08-31-99).]
Posts: 30 | From: Charleston, MS | Registered: Jun 1999
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posted
Ok, let's see if I can make this look right so you can use the formula in the future...
QTC=QMS*square root of[(Vas/Vb)+1]
Where Vb=volume of box (in cubic feet) To derive QTS from QMS and QES, we use the formula QTS=[(QMS*QES)/(QMS+QES)]
So first to find QTS for the formula, we have QTS=[(1.29*3.69)/(1.29+3.69)], which gives us a QTS of (.9558) .
Just for the heck of it, I wanted to check the EBP (Efficiency Bandwidth Product) of your speaker to see what kind of box it would like. That formula is EBP=(Fs/Qes) So, EBP=(60/1.29)=46.511. A sealed box likes less than 50, so good call
Ok now for the good stuff.. Formula for QTC is: QTC=QMS*square root of[(Vas/Vb)+1]. So, QTC=.9558*sq. root of[(.8/1.87)+1] =.9558*sq.rt. of 1.427 QTC=.9558*1.194 So, QTC=1.14
Factoring in the polyfill, which supposedly gives you an apparent increase in volume of up to 20% for each pound per cubic foot, we will have a net box volume of 2.244 cubic feet. Plugging that into the formula, it changes QTC to 1.11, which is a little better. Anyway, I hope I havent confused you, but this is the best I can do on this keyboard. Hope that helps
posted
I agree completely, Dukk. The QTC is on the very high side and will not sound great, as you stated. It will probably sound boomy and peaky with diminished low frequency response..And I was myself when I figured it. wondering about the extremely high QTS Maybe freeair might sound better with that woofer?
Anyway, I didn't want you to have to lower yourself to answer a sealed box question, Oh Port Lord J/K
posted
Thanx guys I really appreciate your answer. The woofer's that I have told you about are for a friend of mine, he wanted the cheapest speakers he could get a still make some noise. SO I got hime 4 JCW cheapo depot speakers, they Only cost him $4.98 a piece. And you are right they are VERY boomy, but that is exactly what he wanted and couldn't be happier. Thanks again.
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Posts: 30 | From: Charleston, MS | Registered: Jun 1999
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posted
LOL!!! I just told that to my roommate. He seems to think that that driver could be used for perpetual motion b/c the cone would never come to a rest. HAHA!
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