How does Fs com into play when designing an enclosure?

[noobslayer77]

hey, just wondering about how the free air resonance of a woofer comes into play when designing an enclosure. Do subs with lower Fs play lower than subs with a higher Fs? Assuming motor force and cone area are the same. Also, what goes into the Fs of a woofer, like what parts of the sub go into the Fs number?

I noticed the Fs on the re xxx 18 is around 15 hz, but most box designs i've seen are tuned between 28 and 32. That seems like a lot of space between the free air resonance and the port tuning of the box.

[DylanBunch]

I could be wrong, but from what I've experienced in sealed boxes and 4th orders, lower the FS the lower it plays. But only when sealed boxes come into play, and like I said I could be wrong but it's just seemed that way with my experiences. A friend of mine had 2 skar zvx 15s (fs of like 39hz) in a 4th and they didn't dig below 30. I've had a Fi sp4 15 (fs of 27-28) and it played down to 24-25hz in a box almost identical spec wise as the skar box.

[Miguels]

if the Fs are too high you need a bigger sealed side to lower the F's

thats what i was told by builders.. im talking about bandpass boxes

[noobslayer77]

I had 2 zvx 15's on a sk 3500 in a 6 cube box tuned at 34 and they didn't go below 30. now i got a w7 tuned at 30 hz that goes to about 20 hz, and the subsonic is set at 30. I've got the 2 zvxs and the sk3500 just layin around. not sure what to do with them lol. i was thinkin about takin them apart and making a frankenwoofer. I like the motor on them, but the spider is like 6 inches, i'd like to run a sundown x15 basket and soft parts.

[noobslayer77]

so for ported, the fs doesnt make a difference? its all about tuning freq? I don't have room for a bandpass

[Miguels]

just because you have the x15 frame and softparts it doesnt mean it will work. the motor has to have clearance for the amount of travel or the sub will bottom out. you can get them to play low on a regular 12 spoke basket

[Swordlordboy1234]

EBP > FS when figuring out what enclosure to run with your subs.

[TRON]

Fs is the frequency where the momentum of the cone, combined with the suspension's stiffness makes the cone move the most.

How tuning the port to the Fs affects output, I don't know. Google it though, I've seen articles the size of the bible on this topic.

[noobslayer77]

Ok. thats good to know about Fs. What is EBP?

[DylanBunch]

What I was talking about has nothing to do with ported boxes or determining what box to put them in, strictly my experience with how subs react depending on FS in specifically 4th order bandpasses and sealed boxes. I do agree with going by ebp to determine what box to put a sub in