So I've got an Alpine Type R 12" and i decided that i am going to make my own sealed box. It says recommended volume is .85 so i am going to go with that but then there were two other columns in the spec sheet that said:
recommended: F3 49hz Qtc .719
What the hell are F3 and Qtc? and do i need to take those into consideration when i build my box?
Qtc refers to the relationship between the box and the subsequent amount of dampening it will provide the rear area of the cone. As the box size increases, dampening (control) decreases, because of the increased air space (volume). Higher Qtc values increase the dampening effect and decrease volume. Generally values between 0.4 and 1.2 should give adequate results. .7= flat response.
It wouldn't be better to make one with 1CuFt. Make one of the correct volume (that recommended by the manufacturers) or the sound will not be as good as it could be. It will sound "flat" if the box is too big.
frkkevin
Unregistered guest
Posted on
You might take into consideration the displacement by the speaker. The box might be made .85 but after you put the speaker in it will drop. The spec sheet should show the displacement of the speaker so just add that to your original .85.
oh yeah i never even thought about how the speaker would be taking up some of the internal volume. WEll i am making my box with a 1CuFt internal volume(which is the recommended maximum for the internal volume for a sealed box so it should be okay) b/c that was the only way i could make the box big enough to fit the speaker in with some room to spare. anyways when the i do put the speaker in then the volume should drop to about .90-.95 which will be still be within the recommened range for the interman volume. so it all works out.
but i did use one of those online calculator things that they have on the net, so do you think that it took that into considerationg when it gave me my internal volume? probably not right?
another question. i am trying to finish up my box before my sub comes,i have the diameter i need to make the speaker hole and all that, but do you think it would be safer to wait and get the template and all the specs to double check?
i did already call Alpine to make sure my specs were right, so i guess it doesnt matter unless there is something that i do now know about?