Fusiondynamics

I have a WLaurent box and it seems the fiber glass back portion of the box seems rather thin? How thick should it be? I have a 8" Rockford Punch 2 in it right now with a bridged 200watt rms to it. Would adding polyester fill inside help it? It does not sound good at all right now. Is it because the box was made too thin??

Thanks in advance!

jwa4378

WLAURENT's boxes can handle much more than that sub and that amp can throw at it. I am not sure of the thickness, but I think the boxes can handle well over 400wrms. As long as no leaking / farting noises are present, its well sealed.

Adding polyfill will give the sub the illusion of a larger area. If your sub is designed for a larger area that you have available, go ahead....couldnt hurt. Subs will sound like crap if they are put in the wrong size box. Check your stats on the box and the sub, and match them. I think the V1 boxes are around .48CF and the V2 boxes are close to .6CF.

John

WLAURENT

That sub should work perfect in the enclosure without any polyfill - however a little would not hurt it.

The key is ensuring you are sealed between the sub and the enclosure. Does that sub have a rubber flange gasket or is it bare metal? You may need to use some weather strip material to seal it up if it is metal.

The enclosures are all 2 to 3 layers of matting - thicker around the corners and where the shell is bonded to the MDF. About 1/8" to 3/16" thick.

May also be tuning - make sure you are sending the proper frequencies to the sub. Cutoff should be around 80-120 hz. Frequencies above 120 Hz will usually make the sub sound muddy. Are you using the LowPass feature on the amp?

Also - what HU and Amp are you using?

Fusiondynamics

I have a Alpine HU (forgot the model but its the one with no pre-outs that most ppl use here) and a MTX 2 channel bridged (Don't know the model off-hand). I am not using the lowpass on the amp. I have it cut off with the HU at 80hz.
Maybe I need to learn and tune the HU. There's too many features I don't understand or the MTX is just not giving enough power to the sub. I opted for the mtx cuz it fits under the passenger seat. It's small so not enough power I assume?

WLAURENT

200Wrms should be fine for a Rockford Punch2 8" sub, maybe a little light, but it should not make it sound terrible.

I might be concerned that the MTX amp is really not giving 200W - they are typically over-rated on the power spec. On their road thunder amps they like to use terms like dynamic power and they rate all their amps at 14.4V power input.

May want to check to make sure your sub is in phase with the rest of the system.

jwa4378

Well, if you are not using the Low Pass Filter, you are probably running a full signal to the sub, which you do not want. When you crossed over the amp at 80 htz, that does nothing unless the LPF is selected.

Check in the FAQ section. It details how to tune the amp.

If there are no pre-amp outputs, I am assuming you are using a Line Level Converter for the RCA's? If not, that could also be your problem. LLC's generally do not sound that good anyways...when compared to a HU with preamp outs.

John

Fusiondynamics

Oops, the outputs are preamped, just no internal amp. I have the low pass filtered from the Head Unit. It's a Alpine CDA-7995. I've read somewhere else that it's better to use the low pass filter from the head unit instead of the amp itself. So should I use the low pass filter from the amp and not the head unit?

Also does anyone else know what the High pass filter should be set at? (It's currently set at FLAT)

I'm running Rockford components at the doors.

00S2K01S4

I was reading this thread and was going to post the same question. I have an Alpine with a pre-outs for a sub amp. I just got the Alphasonik amp from the sub groupbuy (thanks John), and it has built-in filters. Should I hook up the sub pre-out from the HU and use that to adjust the frequency or piggy back the signal from my Soundstream amp and use the Alphasonik filter?

WLAURENT

Do the Alpine amps have crossover freq control and gain control on the HU?

I usually start with the LP for the sub set at 80Hz and the HP for the components set at 80Hz. Depending on the components and the sub/amp combo you can get a better overlap and still have decent sound - like dropping the front component HP at 50Hz if they can handle the bass and you do not have rattles in the doors, etc..

Depending on the music I am listening to I will mod the crossover points from the HU. I use a Pioneer HU.

NFRs2000NYC

Not that I know of. If you plug an RCA into the Alpine's sub out ports, and leave the amp on full range (not LPF) your sub will play all frequencies, which is a no no. Turn the amp to LPF, and cut to 80-120. You should be good (assuming you are well sealed)