Fs in SPL applications

[sandt38]

does Fs have anything to do in a pure SPL enclosure... For instance, let's say I have an FS of 45, a resonant frequency of the vehicle at 45Hz, and an enclosure tuned to 45... Will I benefit? It seems the similar free air, port tuning, and resonant frequencies would compliment each other... Am I right?

I guess why I am asking is, do I need to consider the FS as well as vehicle resonance when tuning the enclosure, or do I just go close to vehicle resonance?

[geolemon]

If your vehicle resonance is 45Hz, and your enclosure is going to be built to exploit that 45Hz tone, that means two things:
1) you might not tune the enclosure TO 45Hz, you want to tune it to whatever frequency causes a big peak just above 45Hz... bearing in mind that your car's transfer function (cabin gain) will cause that peak to move lower by a few Hz..
2) you don't necessarily want a sub that has an Fs AT 45Hz... you want one that is high enough to cause it to yield a frequency response that has a big spike in it near 45Hz..

But I think your reasonings are right, just don't get hung up on the numbers..
Model things out, using WinISD, if you are modeling a sub (any sub), and click the "PARAMETERS" button on the lower left corner of each sub's window, you can change the specs on the fly.
Try tweaking the Fs, and see how raising or lowering the Fs affects the response plot, whether that's something that you want or not..

Talked to my friend with the stroker 18, btw...
He's still got it, he wasn't necessarily thinking of selling it, but he has a Massive 15" that he's anxious to play with, and said he'd part with it for $200 if you are interested.

[sandt38]

Originally posted by geolemon@Nov 25 2002, 11:52 PM
If your vehicle resonance is 45Hz, and your enclosure is going to be built to exploit that 45Hz tone, that means two things:
1) you might not tune the enclosure TO 45Hz, you want to tune it to whatever frequency causes a big peak just above 45Hz... bearing in mind that your car's transfer function (cabin gain) will cause that peak to move lower by a few Hz..
2) you don't necessarily want a sub that has an Fs AT 45Hz... you want one that is high enough to cause it to yield a frequency response that has a big spike in it near 45Hz..

But I think your reasonings are right, just don't get hung up on the numbers..
Model things out, using WinISD, if you are modeling a sub (any sub), and click the "PARAMETERS" button on the lower left corner of each sub's window, you can change the specs on the fly.
Try tweaking the Fs, and see how raising or lowering the Fs affects the response plot, whether that's something that you want or not..

Talked to my friend with the stroker 18, btw...
He's still got it, he wasn't necessarily thinking of selling it, but he has a Massive 15" that he's anxious to play with, and said he'd part with it for $200 if you are interested.

Yeah, I understand tuning lower than resonance, I was just simplifying the whole concept...

That's cool. The 18 would have been too difficult to peak in my enclosure. I was leaning towards regals 15, but I am considering other options...

I may look into the Massive... got a link?

Good idea on the changeup, I will have to try that.

[geolemon]

hehe.. no, I mean he'd part with the Stroker 18" for $200!

He's anxious to play with the Massive, see what it can do... but it's no stroker.
He's somewhat easily coaxed out of his gear, since he usually ends up getting stuff free (or rather, in exchange for building boxes or something), or by trading... he likes to play, dabble with new stuff!

He's not a serious competitor, in that he's challanged to exceed others..
He's more (like me) the sort who is able to appreciate what he can do with some particular piece of gear, if hitting 140 with a pair of eights were a challange in a given class, he'd be stoked to do it, even if he was getting spanked left and right by 12"s... Just fun to see what you can do, at little local "bass off's"

Anyways, speaking of competition, I don't think the Stroker would be difficult at all... to the contrary... have you modelled it up?
No kidding, that's why I made my original statement about the Stroker and sound quality...
Stoker 18" (EBP 158!!), 6, 7, 8 cu.ft. (or whatever you can spare), tuned to 50Hz.. give it a try, models up like an SPL box!

[sandt38]

Originally posted by geolemon@Nov 26 2002, 08:58 PM
hehe.. no, I mean he'd part with the Stroker 18" for $200!

He's anxious to play with the Massive, see what it can do... but it's no stroker.
He's somewhat easily coaxed out of his gear, since he usually ends up getting stuff free (or rather, in exchange for building boxes or something), or by trading... he likes to play, dabble with new stuff!

He's not a serious competitor, in that he's challanged to exceed others..
He's more (like me) the sort who is able to appreciate what he can do with some particular piece of gear, if hitting 140 with a pair of eights were a challange in a given class, he'd be stoked to do it, even if he was getting spanked left and right by 12"s... Just fun to see what you can do, at little local "bass off's"

THE STROKER?!?!?! disbelief...

I may just have to think about that

Damn, what a deal...

Lemme consider

[geolemon]

Originally posted by geolemon@Nov 27 2002, 01:58 AM
Stoker 18" (EBP 158!!), 6, 7, 8 cu.ft. (or whatever you can spare), tuned to 50Hz.. give it a try, models up like an SPL box!

Actually, if you want some boost...

Try this one...

Stroker 18"... 6th order bandpass box...
Rear chamber 4 cu.ft. tuned to 45Hz...
Front chamber 2 cu.ft. tuned to 65Hz...

Hell, use WinISD and overlay that over the ported box curve for the 6 cu.ft ported box...