Ideas for an existing driver...T/S inside

[Warrant]

So i have a couple of drivers lying around for a few years and really don't know what to do with them. My beloved herd of teenagers asked if they would work in the Hobomobile (minivan) as they would like a little more base for that stuff they listen to...hip hop, rap(ish), death metal, etc. I think they might ahve a better use but the opinions here count.

Fs 2.5
Re 6.5
Qes .2
Qms 7.3
Vas 88
Sd 210
Xmax 6.0

Approximately 8" using my built in measuring device. Anything I missed?

[ClosetSciFiGeek]

I think the Thiele-Small measurements you have are suspect. The Fs of 2.5hz is extremely low for any driver. An 8" should have an Fs in the range of say 25 to 55 for woofer use. How did you get the parameters? Do you have a model number?

[Warrant]

Ah yes, the fat fingered typo, the Fs is 25, not 2.5.

These are Fostex Fw200s and the specs are from here, a pdf

[ClosetSciFiGeek]

The response curves for your FW200's look a lot more like an extended response midrange than a subwoofer. This would fit since they are made by Fostex, who are known for building full range drivers. Based on the low Qes that speaker looks better in a ported enclosure most likely. The Vas is pretty big so it might be a pretty big enclosure. I am at work and can't run numbers in Winisd, but you could try downloading it. It's free and you could plug some numbers in and see what you come up with. Try the vented enclosure first, but it will probably be larger than you are looking for. I would then try a simulation with it in a sealed enclosure in Winisd and then based on the enclosure volume that Winisd comes up with run the numbers with a smaller enclosure than is listed to boost the 50-150hz range(this will be the passband your kids will want to hear). Put a cheap solid core inductor on the (+) input terminal for a low pass crossover at about 100 to 150hz and see what it sounds like. By the way with your handle as warrant, are you in the service?

[Warrant]

The response curves for your FW200's look a lot more like an extended response midrange than a subwoofer. This would fit since they are made by Fostex, who are known for building full range drivers. Based on the low Qes that speaker looks better in a ported enclosure most likely. The Vas is pretty big so it might be a pretty big enclosure. I am at work and can't run numbers in Winisd, but you could try downloading it. It's free and you could plug some numbers in and see what you come up with. Try the vented enclosure first, but it will probably be larger than you are looking for. I would then try a simulation with it in a sealed enclosure in Winisd and then based on the enclosure volume that Winisd comes up with run the numbers with a smaller enclosure than is listed to boost the 50-150hz range(this will be the passband your kids will want to hear). Put a cheap solid core inductor on the (+) input terminal for a low pass crossover at about 100 to 150hz and see what it sounds like. By the way with your handle as warrant, are you in the service?

Thanks for the response, I'll try downloading and running Winisd then see what happens.

And yes I spent a few days wearing an ugly green suit, its also the name of my company, ironically a bad choice as everyone wants to spell it warrent.

[ClosetSciFiGeek]

Ran some numbers in Winisd. Try a 0.5ft3 enclosure with a 2.65" diameter x 5.75" long port. This looks like a way to extend the response down to about 58hz(-3db down point). In forcing this driver into this response you will not be able to put as much power into as you would like to. Your kids can have fun with it though. They probably won't care about overdriving it a bit. Good luck.

[Paul Spencer]

Cars have a lot of cabin gain. If you can get a driver in a sealed box down to 60 - 80 Hz (depending on the car), then it can go all the way down with 12 db/octave cabin gain. So a quick guess. Your driver in a Q0.707 sealed box should get to 50 Hz as a rough guess. That will get plenty of bass. The xmax isn't huge but that's probably a good thing with teenagers! A few 8" woofers sealed in a car can make a lot of bass.

There are plenty of tutes on making fibreglass boxes for cars. They might find it fun.

[Warrant]

Thanks guys.