InfraSub driver parameters?

[Hara]

Does anyone have the Sd for this driver?

Dayton RSS390HF-4 15"
http://www.partsexpress.com/pe/showd...number=295-468

The T/S parameters they post there lacks them.

I'm thinking of using this driver for an infrasonic subwoofer <30 hz in a TL. (I can always reuse the driver for other subwoofer designs as I have lots of scrap wood. Also this needs to be a infrasonic subwoofer because the >30 hz will eventually be taken care of by dual dipole subs). Any advice or critique? I just started running simulations so I have nothing to post yet though. I am looking for somewhat flat response incorporating room gain down to maybe 5hz (not looking for high spl levels, just audible/feelable levels)

[GM]

Greets!

If you download the sample response pdf, it lists measured specs and the diameter as 320 mm, ergo Sd = (32^2*pi)/4 = ~804.248 cm^2.

Anyway, even with room gain, you're looking at a huge corner loaded cab and probably more than one sub driver to generate 5 Hz you can feel.

GM

[Hara]

Heh... for some reason I was thinking it was 3.2 cm and thus thinking that was the diameter of the dustcap (although I realize now thats way to small).

5 hz is REALLY low... but even if you can barelyl feel it... that would be awesome.

IIRC, 1-5hz is earthquake range and 13hz is around a helicopter.

The room I'm in is small so I believe the room gain should be pretty good, however, due to price, I'm not going multiple drivers. Again, this is more proof of concept than for hifi.

[Volenti]

I had a little play with mathcad;

250'' (635cm) long un-tapered TL, driver offset 85'' (216cm) from closed end, with a line area of 470''^2 (1200cm^2) internal volume ~27cuft (760L)

[Hara]

Thats actually really nice. I kinda wish the the models showed the response below 10hz. I'm still trying to learn how to use the models. Which worksheet are you using?

[SteveCallas]

Unless I'm missing something, you're not getting too much from such a large TL. Take a look at 325 liters using a 6" diameter port that is 26" in length (~14.8hz tune) with 200 watts per driver. With these drivers, you'll typically want to get two, as they aren't output monsters.

[Hara]

Thanks for the suggestion, if messing around with the worksheets gives me nothing I'll try that (or try both, I have LOTS of scrap plywood).

I think I'm getting the hang of using the TL worksheets, just a matter of following the directions.

[preiter]

Check out this project:

http://sound.westhost.com/project48.htm

It's a subwoofer designed to operate below the resonant frequency. Since your high end requirements are so low this may be perfect for you. And it keeps the box size reasonable.

[BassAwdyO]

I think that dayton isnt a bad sub to try out on an infrasound project, but remember displacement is key when it comes to putting out low bass.

So two will definately be better than one, but by all means you can add a second later instead of buying them both at once(and if you really are satisfied with one... well I wouldnt think you were sane, but you could just keep it that way)

I'd suggest going with a sealed/ported box. Now if you're going for 5hz sealed is the only way to go, and you're never going to get there with less than 4 of these drivers and serious EQ. Ported boxes would require extremely long and large ports. PRs are an expensive option. TLs arent meant to go that far below a driver's resonance(18hz Fs here I believe).

If you just want to get infrasonic(what i reccomend) build a large ported box tuned to ~16hz. I wouldnt go any lower than 15hz because you're going to loose so much efficiency that the port wont really make a huge difference. I wouldnt go higher than 18hz because this is considered audible and can be at high levels.

The port should be reasonable for 16hz tune unless your enclosure is under ~6.5 cubic feet

[Hara]

Great feedback. I'm not really concerned about box size so WAF is not an issue. Still single anyways

The Sub-Woofer Controller project may not work out in my application simply because its sealed. I'm trying to maximize the low frequency output using as little drivers as possible, afterall, anyone can go as low as they want given any amount of drivers.

Using the xmax, frequency, listening distance, spl equation, a sealed sub of 805 cm^2 at 14 mm travel will give a spl of 91 db at 7hz with a listening distance of 2 meters. By adding output from a port and adding roomgain, I don't see this project being too farfetched.

Its interesting how both BassAwdyO and SteveCallas both recommend a BR. I thought a TL was the best way to gain extension, no matter how ugly the response.

The way I see it, I'm trying to minimize driver displacement relative to an infinite baffle design while keeping spl as high as possible, than equalize room response to reasonably flat.