bkolfo4

Thanks. I will find out what he is using now.

My 13 yr old is trying to learn about video editing. . . He has a HD PVR that he is using to capture XBox360 and I recently won a HD video camera from a "stacker" machine in a Walmart that he is using too. He has software to edit the videos, but the only program he has to add music to the video will not save the file in HD format (only AVI or MP4). Even at the highest quality setting, it is nothing like the original HD format. Can anyone recommend a good software to do this that will not cost an arm and a leg??? He did this video yesterday: Brian

Need to know what amp to answer correctly. Is it 1 ohm stable? Is it truely 5000 watts? Can those subs handle 2500 each? I would worry that is a lot of power to be playing with if you are asking this question. . .

^^^^this!! By the time you get the correct size slot port in that box and account for driver displacement, I bet you are around 5 cuft. Might want to look at aeros instead of a slot.

Ask PSI. If you think you have too much power, ease into it a little more each day and watch the excursion (can be controlled with SSF) and the burning coil smell.

The one from RE is crap. I have corrected at least 10 L-shaped ports for people who have used it. . .

I don't see what type of 12" subs they are, but 2 4" areos will work with a pair of 12's. Ever see the great 12" challenge a few years ago? They were doing crazy numbers with a 12" BTL on a few thousand watts and a single 4" aero. PSI ran a pair of MT 15" with 4 4" aeros and did mid 150's playing music. . .

Run 4 of these per tower: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-1020

No.

What does it look like if you cut the port width down to 9" wide? If it was mine, I would take 81 sqin of port and whatever gain in Net volume that gave me.

If it was me, I would want the tunIng around 34 for daily. I have had a couple of boxes at 38-40 and they do lack a little on songs with really low bass. If you stick with 38, just make sure your subsonic filter is set correctly to keep the mechanical excursion under control (you did not mention how much power you are running).

Since port area is not determined by box volume, don't stress too much. Edit - I missed the entire title (on my phone). Eighty sqin is definitely not too much port for a NS 18. I would go up to 100 sqin. Very seldom would you ever have too much port area in a car enclosure, so as long as you can get the length you need for the tuning you want, you will be fine.

"peaky" means a big hump in the frequency response just above the F3 point. A box being peaky is not caused by the port size (unless it is undersized and has too much compression), the tuning frequency vs. the box size vs. the driver parameters will determine the frequency response. High Q designs will have more peak. Usually works out great in a car where cabin gain boosts the lower frequencies. That is why you see car subs tuned 30-35 Hz, but home subs tuned down around 20 with drivers that have different t/s parameters (or amps with EQ on the lower end).

In a car, 30 Hz is low enough. You also need to look at the design vs. the woofer parameters. Tune too low, and you could end up with a dip in the response just above the port tuning frequency.

Only way to know your impedance is to measure it at each frequency and plot the results. There are several ways to measure it. If you have a DMM and clamp, use ohms law. If you only have a DMM, you can add a series non-inductive resistor and look at voltage at the amp vs. the voltage across the known resistor. The difference is the voltage dropped across the sub. Current can be calculated by the voltage across the resistor / value of the resistor. Once you know the current and the voltage across the sub, you can calculate the impedance at that frequency.

Edit - double post

Does not matter for daily. Competitors can use the impedance info at the frequency they are competing with so they can maximize the power on the subs.

No on the bigger magnet comment. A subwoofer is a magnetic coil with an inductance. When you input AC current, the resistance (actually called impedance) varies depending on the frequecncy of the AC signal. A woofer has its own impedance rise at the Fs of the woofer. A 4 ohm woofer is WAY above 4 ohms at Fs. Many people do not realize this and understand that the impendance they are calling "impedance rise" is actually there with the woofer out of the box. But that being said, putting the woofer in a box also creates additional impedance spikes due to the box resonance and the port tuning. Impedance of a subwoofer is based on an average as long as it is a certain percentage over the minimum impedance (a google search can explain how driver nominal impedance is calculated), but it is not a flat X ohms, and like I said, it rises well above the nominal rated impedance at Fs. Impedance rise without a box

I left mine on and built around it. Was a little more work, but was nice opening an closing the door.

That video made me laugh. The heat example was a little off. . . Current will generate more heat with a given load but if the load changes, you still have to look at the actual power. Example - which will generate more heat: 50 amps across a one ohm load, or 2 amps across a 50 ohm load? If you know the answer, you will see what I am saying. I have no doubt the parallel coils were louder, but the sub it self has several parameters that change when you change coils that will contribute to the difference. A better test would be the same sub with a X amount of power with the coils in series and then the same amount of power on the same sun with the coils in parallel.

In parallel, the voltage across each coil is the same, and any slight differences in the coils would cause the current to be different. In series, the current through each coil would always be the same, and any slight differences in the coils would cause the voltage across each coil to be slightly different. Unless the sub has an issue, these 'differences' are too small to notice and do not hurt anything either way. Wiring in series or parallel will be determined by what is available with the woofer you want to purchase vs. the load required to maximize your amp's output.

I came up with a different volume than both of the above, so I modeled it in ProE and let Pro determine the volume. It is 2.6 cuft (or 2.599336516) as it is drawn and dimensioned above. If you use an aero, can it be placed in one end, or is there interference in the vehicle? Length will be an issue with 32 Hz tuning if you only want 1.5 cuft. What you have there could work great with a single 12" or dual 10" at the volume you have.

There are not enough dimensions there to calculate the volume. Need one additional horizontal dimension across the bottom piece, or the angle of that lower angled piece to calculate the volume. Any volume calculations from that drawing would have to make assumptions, or measure that angle as close as possible with a protractor. Brian

Edit - I just noticed this post is 3 months old! The Massive Nano N2 is $169 shipped. I have used them in multiple installs, and own 3 of them myself. One is in my wife's car on a 12" Q in a sealed box. Very nice setup. Ebay item number - 200618986270

Also check with PTC to see what they can do. They built the transmission and torque converter in my big block silverado. Awesome guys that have been in the business for many years. http://www.ptcrace.com/