need advice on enclosure for rf shallow mount subs

[apexhomeinstallations]

Hello all!

I have an aquaintance that is quite young and naive, i say naive because none of his equipment matches not because im bagging on the brands , but anyway...went out and bought a set

of rockford prime r2sd2 subs in the 12" variety and slapped them in a pre fab

sealed enclosure at about .75 cubes per sub with a crunch px1000.2 amp ...obviously

running 4 ohm to each channel because that amp wont do 1/2 ohm.

I have explained to him he is lucky if he is getting 50-100 watts to each sub, but

now that all that is aside.

His enclosure got wet and blew apart somehow , i dont know how i only met him

because a friend referred him to me to build an enclosure for these as i guess im the most experienced person he knows and im not THAT experienced. I got excited

at first but then....

I did the usual, looked at the manufacturers specs and manufacturers

recommendations and then i ran several scenarios through winisd only to find that

the ebp was super low on these subs and then i read the description finding

rockford actually says in the print that these are optimized for sealed enclosures.
 

SO....

*He has plenty of room to work with in the extended cab of a 2000 model chevrolet

s10.

*I much prefer vented enclosures with as flat of a response as possible but just

not sure with these subs. Best i have modeled is a 4 cube box tuned to 32hz.

*he is a typical teenager which wants boom-however i wont let him be a one note

wonder so overly peaky boxes i wont build.

*I read somewhere that these subs hate ported boxes, however this person possibly

had other issues.

Can someone give me some advice on this one? Possibly someone that has used the

subs in a vented enclosure or even ext cab s10 owners that know the best

positioning for ports/subs etc.

I know these subs are made to go under truck seats in tiny sealed boxes, i know this is not at all optimal given the situation. But i want to give the young man more bang for the buck -pun intended.

Thank you in advance.

specs below.

 

 

 

 

Size:     12"
Nominal Impedance:     Dual 2-Ohm
Power Handling (Watts RMS):     250 Watts RMS
500 Watts Max
Voice Coil Diameter:     2" (50 mm)
Magnet Weight (oz):     51 oz. (1.45 kg.)
Speaker Connector:     Dual 12 AWG compression
Fs (Hz):     29.7
Re (Ohms):     3.80
Le (mH):     4.2
Qms:     9.00
Qes:     0.71
Qts:     0.66
Vas (Liters):     65.4
Sd (cm2):     534.8
SPL (dB @ 1w/1m):     85
Xmax (mm):     10
Woofer Displacement:     0.039 cu. ft. (1.1 Liters)
Cutout Diameter:     11.25 in. (285 mm)

[reedal]

You do not have those subs wired at 4ohm if they're D2. I'm assuming there are only two subs because you didn't say how many. Just "a set". You can either wire them at .5ohm, 2ohm, or 8ohm. Assuming you had them wired series-parallel, then 2ohm is the magic number. 

Second, those subs really are better suited for sealed.

[apexhomeinstallations]

each of 2 subs is wired for 4 ohm with each sub wired individually to the 2 channels of the amp. stereo. not bridged. This particular amp only does 4 ohm stereo 2 ohm stereo or 4 ohm bridged.

Thanks for the input on the box sir.

[reedal]

My bad, misread what amp it was. Carry on  

the issue with running a ported dual 12" enclosure that I can see is that you likely won't have enough space. Even though they're shallow mount subs, they still need to have the appropriate net volume and the appropriate amount of port area. You could probably squeeze out the net volume, but not with enough port area. Or you'd have enough port area and not enough volume. 

 

If you post up the dimensions that are available available to work with (don't forget to account for the trans hump in the floor if it has one), then someone should be able to give it a shot at trying to design one. Earliest I'll be able to plug some numbers for you is tomorrow some time.

[SGTSKIP]

Is he trying to mount the subs under the seat or build a box to sit on the rear seat?

Me

 

[apexhomeinstallations]

we have the entire extended cab portion to work with, seats removed, gonna build a platform to flatten things out back there which will rise about 2".....he doesnt care if it gets walled or not.


i have already figured out i can go 16x16x46 easily, which will allow me to flip the box around in 8 different locations (port up sub up,port forward sub forward, port downfired sub downfired, port rear sub rear loading off back wall..and swap sides by flipping the enclosure  using a supposedly proven design borrowed from spl competitors in an ext cab s10 of 2 subs as far to passenger side as possible and port as far to driver side as possible.) and give me in excess of 5.5 cubic feet internal volume i believe. And 5.5 cubic feet is for starters since the rear windshield sits at 24" height there is a lot of volume to be had back there.

manufacture spec says .90 sealed, 1.79 ported but we all know the f3 on that is not ideal neither is the group delay.

without sounding like a know it all id like to say im more here asking if anyone has experience porting this particular subwoofer, i know how to use modeling software for enclosures i just dont have experience with this shallow rf sub, nor any shallow sub.

 

[reedal]

I was unable to find any topics on this forum that have those subs in a ported enclosure.

[apexhomeinstallations]

4 minutes ago, reedal said:

I was unable to find any topics on this forum that have those subs in a ported enclosure.

google unfortunately is pretty well the same result lol.

[06RTCharger]

Could u talk ur aqaintence into selling those shallow mounts and picking up some regular subs? 

[apexhomeinstallations]

For anyone that comes along later wondering how these sound in a ported enclosure.....

 

I went ahead with what winisd was telling me, going by the parameters everything looked good on all the graphs and i guess i should have just not questioned what it said because those teeny tiny little shallow mount primes surprised my near middle aged ears.

 

in the proper ported enclosure those little subs are BANGIN (for what they are)
 

4.06 cubic ft tuned to 30.15hz slot ported....i was surprised, the look on the kids face on the first low bass note PRICELESS.