PPI power class subs (PC.124) Small ported enclosure @1500 watts

[mooresound]

So I want to change the sub stage in my wifes ride and have been on a PPI kick with their phantom amps. Plus, I also have a couple of power class amps in that vehicle for the mids and tweets.

Anyways,
I took a look at their power class subs and have an idea on a setup. but to ensure I'm not crazy and to gather user experience I would like some input.

*** this is more of an SQ design.... Id like to keep enclosure size down and limit needed EQ....

Sub:

PC.124

QTS: .45
QMS: 5.82
VAS: 1.271
QES: .49
FS: 29.53
SPL: 84.4
RE: 7.20 (Series is assumed)
PE: 800
BL: 26.6
XMAX: 15MM
XMECH: 22.5MM
SD 73.07 INCH


Enclosure design:

2.25 CU FT
FB: 30Hz
F3: 30Hz

Model:

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[Joe X]

A couple of things, WinISD does not account for cabin gain so that plot is not what you will get, then what will be the vehicle and the exact amp? 1500 RMS may be a little too much heat for that sub.

[mooresound]

Joe, Im tracking on the cabiin gain.... minus JBL's graphs of various vehivels, cabin gain is an art not science. Assumidly F3 will go down.

As far as heat.... that two subs modeled. RMS for each is 800 (prolly a tad high) so 1500 should be fine for two. It prolly would have helped that I put that in my thread though, huh? lol

What took me was that two 12's modeled well (minimal gain, low F3) in a nice 10's enclosure. 2.25 cubes is not a lot of airspace for two 12's ported... its mor along the sealed enlcosure size. So i made this thread to get some opinions adn double check my work.

[bbeljefe]

At first I got a completely different plot, until I looked up the manufacturer's website and realized Vas was in square feet rather than liters...

But once I got it right... looks like you'd be better off with only one of those drivers if all you have is 2 ¼ cu ft feet to work with. One driver tuned to 35hz in that cabinet yields a 3db boost at 40hz, is flat at 30hz and goes 3db down about 5hz lower than your configuration.

If you're looking for SQ and you already have the 1500 watt amp, I'd consider running it gains down on one woofer or, perhaps, finding a couple of eight or ten inch drivers that could handle the power while also performing well in a small enclosure. Although from the looks of it, PPI isn't much in the business of high powered, small diameter subwoofers.

That's a pity too because I've always been a fan of PPI. I only ever owned one of their amps and that was a 2030 (60w two channel) back in the mid eighties, running two Petra 15s in a bandpass blow through in a Nissan truck. Imagine that... 30 watts on a fifteen and nowdays we're running 300 watts to mids.

Sorry for the nostalgia. :-)

[Joe X]

Joe, Im tracking on the cabiin gain.... minus JBL's graphs of various vehivels, cabin gain is an art not science. Assumidly F3 will go down.

As far as heat.... that two subs modeled. RMS for each is 800 (prolly a tad high) so 1500 should be fine for two. It prolly would have helped that I put that in my thread though, huh? lol

What took me was that two 12's modeled well (minimal gain, low F3) in a nice 10's enclosure. 2.25 cubes is not a lot of airspace for two 12's ported... its mor along the sealed enlcosure size. So i made this thread to get some opinions adn double check my work.

So it was two subs sorry about that, 1500 RMS will be fine.

When you do these plots is never a question if those are or not going to be off, the question is by how far, just adding a generic cabin gain you get this:

Sealed on blue ported on red tuned to 30Hz both 1.25 cubes net (actually that's big for the sealed):

F3 of course goes down but cabin gain has an effect elsewhere in the bandwidth of the sub as well.

Group delay:

Group delay related to transient response looks really worse than sealed.

So these's some feedback.

[mooresound]

Hey guys thx for the input.

bbeljefe: Unless I am going for output, that 3 DB gain that is so common place and destroys imaging. I prefer to lose the gain and maintain a more linear response.. cabin gain will add to it. As well, I love PPI. I think they are putting out a great product at a good price point and they have come along with the times(budget equipment and small box sizes rules the world). See my sig for my truck set-up

JoeX: Nice point on the transient response. I forget what is said to be acceptable, but transient response is directly proportional to port length and with small enclosure port length gets long.... its the nature of a compact car, lol. I may go looking elsewhere for a sub to meet my needs. I am trying to pick up a FIQ 12 used on caraudio.com.. 1.75 @ 32HZ if the price gets right