Please, verify my math.

[ostie01]

Hi, I bought 2 Eminence Definimax 4015LF. I want to put them in a 5.5 cubic feet box with a vent that is 2'' X 15''. The vent is 6 in long right now. BassBox 6 pro calculate a F3 at 57Hz, Is this OK. I can't modify the dimension of the vent but can make it longer or shorter. Actualy, one woofer per box. 57 HZ is pretty high , would like it to be around 40. Please advise. Thanks for your time.


http://www.usspeaker.com/definimax4015lf-1.htm

http://www.eminence.com/pdf/cab-definimax-15lf.pdf

[roddyama]

An Isobaric arrangement in the same size box (~5.5cu.ft.) will get the f3 down to the 32Hz range with a relatively flat response, but it depends on what you want to listen to and what performance characteristics you want to optimize.

[ostie01]

Thanks for the reply. My boxes are already built, so would like to know how they will sound in those boxes. If it's better to make the port longer or shorter to get a good F3, not really the lower is better for me but to get a good bass. What will be the difference between a F3 of maybe 34Hz and one at 40Hz, any effect on the amplifier. Just forgot to mention that they are crossed over at 120 Hz at 24dB per octave.


This is for stereo use only, no movie.

[roddyama]

Do you have one box or two boxes?

Are you putting one driver in each of two boxes or are you putting two drivers in one box?

[ostie01]

Actually, this is one driver per box, each box is 5.5 cubic feet with a port 2 X 15 X 6 long. I think I will put them in the box and will measure the F3 with a Dayton woofer tester I bought last year. I can put a solid block of wood in each box to make it smaller if I need to. My goal is not to get a F3 of 25Hz but something between 35 and 40Hz.

[roddyama]

With one driver per box and a 12" port 15"X2" dimensions gets you pretty close to flat response with a tuning frequency of 42Hz f3 of about 39Hz. Thats not bad. Making the port longer tends to lower the f3 slightly but gives you a little bump in the bandpass. Either way it doesn't look bad on paper. All you have to do now is try and see if you like it.