EuroDriver

iTrader: (21)

I'll start by saying I can figure out a motor or suspension like the back of my hand, but when it comes to electronics and audio technical stuff, I'm among the most pathetic of morons. So basically, any help in this area will have to be spoon-fed for me to understand.

That being said, I'm looking for advice on what to do (if anything) about a sub box that I purchased, which has too much air volume for my subs. The box is a dual-chamber, with 1.25 ft^3 per chamber. (This is the box: http://www.zenclosures.com/Nissan-Ma...x-p/max5th.htm).

My subs are Fosgate P2D210, which call for either 0.59 ft^3 sealed, or 1.4 ft^3 ported.

Here's the specs on the subs:
Size 10" Nominal Impedance Dual 2-Ohm Power Handling 250 Watts RMS 500 Watts Max Voice Coil Diameter 2.0" 4-Layer (5.08 cm) Magnet Weight 62 oz. Double Stacked Speaker Connector Dual 10 AWG compression Fs (Hz)29 Re (Ohms)3.00 Le (mH)3.6 Qms 9.90 Qes 0.50 Qts 0.48 Vas (Liters)32.6 Sd (cm2)340 SPL (dB @ 1w/1m)84 Xmax (mm)13.2 Woofer Displacement 0.052 cu. ft. (1.47 Liters)

For one, I'm breaking my head debating whether to keep the box sealed, or to port it. My stereo shop is practically screaming at me to go ported, but I'm not sure whether that's the best for me, since I'm not looking to be shaking the ground from a block away - my system is rather modest, which I built for SQ more than for booming along, although I do like some boom here and there. The shop's rationale is, that since my subs are in the trunk, I need the extra loudness, and I'm not going to appreciate (or even like) the sound effect of a sealed box, since it's not inside the passenger compartment. Rather than arguing with them, I just purchased my box from the above site (and it was cheaper, anyways).

I would like to at least try it out as a sealed enclosure, and the box is right in between the dimensions needed to run it ported, if I ultimately opt for it.

My main question is, whether it's a bad idea to run it sealed with that much additional air volume. I'd imagine I would get a deeper sound, but IDK if the sound quality would be terrible, or if I would be risking damaging the subs. I could reduce the airpace with wooden slabs (I read stuffing it with polyfil is not a good idea). In the alternative, would my best option be to take advantage of the box size and port it, even though it does not have the ideal volume for my subs? (correct with polyfil?)

Just to give you some background, here's the info on my current setup:
HU: Kenwood DNX9990HD
Fronts: Fosgate T1652-S (6.5" components)
Rears: Fosgate R1653 (6.5" full range - running off HU rear channels)
Amp: Fosgate T400-4 (rear channels bridged to power sub)
Sub: Fosgate Punch P2D210 - 10"
Box: Generic ported box (since shop insisted, but I don't like the sound - often too weak or too hollow)

Once I install the new sub box, I will be adding a second 10" sub, and I plan to power the subs with either a Fosgate Punch 500-2, or the T600-2.

What would be my best options? Sealed as-is or reduce air space? Ported as-is or with polyfil? Other options?
All suggestions appreciated!

EuroDriver

iTrader: (21)

73 views & no one can help me where's all the audiophilez?

AznRyan

iTrader: (1)

I didn't answer, b/c I don't know enough to give you the best answer. djfreestyl is one of the audio guru's, and helpful with things like this. If it was me, I'd send him a pm.

He also makes some well-built spare tire covers that replace the flimsy piece that Nissan uses in the trunk. I got one to support additional weight from a box, and I'd recommend anyone else to do the same.

Good luck with your dilemma, I hope you can get an answer!!

AscendantMax

iTrader: (7)

The increased air space will lower your sub's power handling, so it'll be easier to push them to their mechanical limits with lower power. Be careful on how much power you're sending the subs when they're in a large box. It'll also allow them to play the low stuff a bit easier as well, since there's more "slack" in the acoustical suspension in the box. It shouldn't affect the quality of the sound though, so I wouldn't be concerned in that regard.

Porting a box is a bit more involved than just adding a port to a box. The length of the port, port area, as well as the internal air volume of the box will dictate the port's tuning frequency. If you're not looking for a ton of output, just go sealed and call it a day.

EuroDriver

iTrader: (21)

Thanks for the replies. I'm thinking I might run one sealed and one ported. My box arrives next week. I already studied up on the porting requirements, so when the box gets here, I can start measuring up.

Since I have to buy a second sub, any recommendations on a quality sub that can take advantage of the box's air volume?

AscendantMax

iTrader: (7)

wait....so you're going to run both a sealed and ported box at the same time...?

EuroDriver

iTrader: (21)

Sure, why not. Seems to me it would provide the fullest sound possible. Isn't that the concept of those plexiglass enclosures?

AscendantMax

iTrader: (7)

no, those "plexiglass enclosures" operates on a totally different principle. they're known as bandpass enclosures. one chamber is sealed, and the other chamber is ported, BOTH working in unison to produce a very distinct and often loud frequency range. you can't just put a sub in a ported box, and another sub in a sealed box and expect the same performance.

you'll face the issue of having two speakers that will handle two different power levels due to the two enclosure types. if i were you, i would just put both of the speakers in a sealed box and call it a day.

Hillsboromax

A sealed box no bigger than 1.5 cubic ft will do u just fine.. It don't have to b built like a coffin but it does need to b sealed properly.. Even a ported box da same size or a lil more for 2-10" will b just fine.. Too much airspace will make them flutter or sound like u wasted ur $$ when all u need is a GOOD box...

EuroDriver

iTrader: (21)

I did some research on this and you are right - I'll probably stick to the sealed enclosure.

That's what I'm worried about, because my subs call for 0.59 ft^3 for a sealed enclosure, but my box has 1.25 ft^3 per chamber.

maxgtr2000

iTrader: (29)

You can try the subs in that box that you have now to see how it sounds. If it sounds good you know what to do. The more airspace will allow them to play lower bass as has been said before. If you don't like the sound you can sell the box, buy a more specific box, or fix the box you have. A friend that owns a shop would always build his personal boxes sealed closer to the ported specs.

EuroDriver

iTrader: (21)

Yeah, that's my plan for now, to "test" it as-is, like you suggested. My worry though, is that apparently (from what I have read), I risk destroying the subs if the box is too big, because too much airspace does not give it enough suspension, which can cuase the coils to bottom out, or something like that. Like I said before, I'm planning to run them kind of mild - 250-300w RMS and I don't really crank it to the max.

If they sound too hollow, I'm just going to put wooden boards in the box until I achieve the desired airspace.

I have also been looking at some alternate 10" subs that call for that much airspace, but haven't found much, especially in the price range.

maxgtr2000

iTrader: (29)

Just check the excursion measurement in the specs and at max volume you would play try to determine if it is reaching that measurement, as you said playing them with a safe power you should be fine.

AscendantMax

iTrader: (7)

Not true, large boxes wont make your sub flutter. It will, however, lower your power handling and help augment lower bass notes. But yes a good box is very important!

EuroDriver

iTrader: (21)

Well, just thought I'd let you all know what I ended up doing. I left the box sealed, at 1.25 ft^3 per chamber, running two Fosgate 10" (P2D2). I'm powering them with a Fosgate T600-2.

They sound very good, but sometimes the upper lows are a beat weak, whereas the low notes hit very strong - close to the sound of a ported box. After fiddling with the equalizer & crossover, I like the end result, although I'm still pondering whether to reduce the box volume a little; maybe closer to 1 ft^3. I might do a temporary reduction with some 2X4's, just to see what the difference would be.

Here's some pics...

The Box & Subs:



Amp Setup:

AscendantMax

iTrader: (7)

yeah just try to reduce the airspace a bit...it'll help out with the upper bass response. what's your low pass crossover set at?