ok i have a RF P210S4 atm its in a sealed .6ft^3 box bc well that's what it's in. It saves me trunk space i my 07 Fusion(grocery/family wagon) it's hooked up to an Ultimate T1200amp running 200rms on 4ohms. It's entry level I know but money being what it is I want to make the most out of what I have. I have all the T/S#'s from it's spec sheet. It's performed well for me but as i mentioned in a previous thread it seems to be missing some of the lower tones when rap/hip-hop is on. I aim to do this over the summer I have access to all the needed tools and supplies for carpentry. thx in advance. Oh space is still at a premium HUGE is not an option.

 

1) VAS (volume of air that offers the same degree of restoring force on the cone as that of the cone's suspension)
2) QTS (the total quality factor of the speaker at Fs)
3) Fs (the resonant frequency in free space)

A loud speaker and it's box have there own Q (quality) factor (Qpb=Q of ported box , Qts=Q of speaker)and together they form what is known as the system Q. A system Q of 0.7 gives the smoothest roll off in the low frequency response of the system. Above 0.7 causes a hump in the bass response and below this causes the bass to fall off at a higher frequency.

Now if the volume of the box is Vb, rearanging the following equation,

VAS/Vb=(Qpb/Qts)^2-1,
Vb=VAS(Qts/Qpb)^2+1

eg.
Vb=2.88(0.42331/0.7)^2+1
Vb=2.05 cuft

A Q of .7 usually makes for the best sounding enclosures. Now for SPL, a higher Q is usually favoured giving a bump in the response curve.

HTH

p.s. all this changes as soon as your sub is broken in though, lol Thats why it's usually trial and error. I just play with WinISD and/or BB6P until it models well. Then I build it and tune from there.

 

Some stuff to make your head hurt... lol

Incase that wasn't enough...

 

Ok how does one get the Qpb of the enclosure, from the programs?

 

.7 is ideal for a gentle slope (no peak). Unfortunately I only really try to use .7 for sealed enclosures. Otherwise, your going to want a higher Q #. Just model different enclosures in a user friendly app like WinISD and go from there. If you can get it to accept your subs T/S it's always a bonus.

 

ah man those sights made me do algebra again got some interesting numbers from the second sight(easier to read imo), i'll have to give it a go with the programs when i get home from work. I appreciate the input...what the hell is your tag name? some form of 'leet speak?

 

lol, no... my laptop is a VGN-N130G. Thats were is comes from. I'm thinking of changing it to my team name.

 

That's alot easier to give kudo's to deadly.
I used WinISD, still scratching my dang head a bit, it gave me the needed cub.ft but no specific measurements...does that mean that as long as I meet the vol. needs, the dimensions are negotiable

Be patient with me, the street I grew up on had a sign on it that read "Slow Children at Play"

 

lol, I've been meaning to change it. Just had to come up with a name that noone else had first.

Yes, just design around the internal volume and port area you've come up with. Just remember that the port and sub displacement are subtracted from the box area to yield your final internal Vb(volume).

ie. if you've come up with a box thats 1cu... you have to add the space that the port will take up (if using one) and the amount of space that the sub displaces.

So it might be something like this:

1 cu internal
.14 cu for sub displacement
.5 for port displacement

Therefor your overall internal volume should be 1.65.

If your going sealed, use this to help.

If your going to try ported. This will get you close and is a good visual aid. Just fill in the red areas with your own info and adjust it till you get numbers similar to what you liked in WinISD. ie. internal volume and tuning frequency.