Formula to figure out the QTC of an enclosure?

My question is, what is the ideal QTC in a sealed enclosure for 100% SQ with SPL not being a factor. Some say .707, others say .5. Also, are there any formulas to figure out the QTC of my enclosure. I don't want to use a box building program since they are not accurate. I am pretty sure I seen a formula to figure out the QTC, but can't remember where.

Thanks, Dave



Last edited by FaintReality at Sep 21 2002, 03:20 PM

 

I used this formula: You substitute any Qtc between 0.50 and 1.50 in place of 0.70 in both equations (both must have same value) to experiment with enclosure size. For Vas, use ft^3 not liters.

Find alpha: X = (0.70 / Qts)^2 - 1

Then calculate enclosure volume: Vb = Vas / X

After reading and speaking with Dan, I have decided to go with a QTC of .577 to achieve the best transient response, and it will make the best of my 500w rms to each Brahma (JL 500/1 amp for each 10" Brahma).

With all this stated, I substituted the .70 with .577 in the equation. I got a final Vb value of .69ft^3 to achieve a QTC of .577. Is this correct?

10" Brahma QTS=0.41
10" Brahma Vas=.678ft^3

 

I found an online calculator which gave me an enclosure volume of .691ft^3 to achieve a QTC of .577, so the formula I posted above was correct. With this in mind, I am assuming I would have to subtract 3L (0.1059ft^3) for driver displacement and for any bracing correct? The .691ft^3 is what I want to achieve once the speaker and all bracing is enclosed in the enclosure?

So, for example, if I didn't use any bracing, I would want an internal volume of .80ft^3 so that once the speaker is mounted in the enclosure I would have an internal volume of .69ft^3?

Thanks, Dave



Last edited by FaintReality at Sep 19 2002, 02:07 AM