Lord Huggington

iTrader: (1)

I used to think anything below 1000W wasn't much but it's just not true. My friend has two inefficient sealed 12's in his ext. cab getting 150W each (670 rms each lol) from a very old n' crappy amp and they vibrate the hell out of everything.

sx4life

iTrader: (1)

upgraded alt is last on my list, I have ran 3k amps for past 4 years never done one its not necessary.
Battery I keep a good battery in my vehicles and its worth the money spent.
BIG 3 is a MUST I have nt done it in my civic but it needs to be done, its the most cost effective thing I do with my stereo I think.
gl on the system keep us informed with your results

sheptard

iTrader: (2)

Bigger battery is pointless if the system can't keep it charged.

Find out how many Amps your stock alternator actually puts out. The number supplied (Say, 105A) is only going to be at 3k engine rpm. at idle, you are looking at a more realistic number of 45A-60A, 60 being really high. You will see quickly that you really don't have a lot of power to play with.

However, at 650W RMS it's not as big of an issue if you were running say, 1200+W RMS. Also it depends on how loud you're going to have your system.

Bigger battery only makes sense if you're going to be listening to the system when it's off, and if so, you are much better off installing a battery isolator with a second battery. It'll make sure your starting battery will always have juice.

I personally like caps, They are a great buffer system which helps smooth out power delivery to the amp. Since the power draw for music isn't constant, you can run into issues where the alternator isn't able to immediately supply the amperage your amp needs to hit those low bass notes, which means you start running into voltage drop as the system needs to look to the battery for that power, so your amp gets less efficient.

However, again at 650W RMS, this isn't as big of a deal, haha.

Finally, as everyone else here has said, for the love of god please do the big 3 or at a minimum, the big 2. It's probably the single most effective thing you can do to help your cars electrical system and is a fun afternoon project.

gtabmx

Thanks for all the replies guys. Today I bought and cut all the wood I need after drawing it up in AutoCAD and testing many many design, volumes, and tuning frequencies on winISD. Tomorrow I will be assembling the enclosure and hopefully lining the interior with foam wave cones. I might be able to get some for free is some specialty product packaging, and they look similar to these sheets, except they are smooth spherical cones as opposed to triangle ones

Link here

My enclosure will be a ~70L (after subtracting the tube and sub displacement, but not subtracting the foam i don't have yet) ported box, tuned to about 41Hz with a theoretical SPL of 119.9 dB @ 49Hz @ 200W rms. The variable parameters I have to work with once the box is complete is the Low Pass Cutof, the 50Hz-cenetered Bass-EQ Boost (0 - 12dB), and the Gain (I can go up to 400W rms on this sub), not to mention the actual HU volume. However, only certain tunings will work since any changes of one parameter without compensating for another will cause over-excursion at around 50Hz. With certain tunings, I can get theoretical SPL at higher frequencies, but I hear 120dB is the threshold of pain...

Saturday is the big wiring and setup day. Can't wait to press play...

-Mike

Oh, and it's not that I am skeptical that the Big 3 is essential and worth it, it's just that at the moment, I can't justify the price on a system of a max rms of 600W that I have yet to hear. Maybe dimming lights will convince me to just do it.

godzilla1978

130db is the threshold of pain for most people. If your sub and box only gets to 120 on 600rms there's something wrong. I get 138db on music and 140+ on test tones with the same power!

Dukk

The computer predicted 120db is free field. The transfer function of the car will add significantly to that figure.

gtabmx

m

My entire system is 600W rms, but the sub alone is just 400W rms. The reason its "just 120dB" is because of what was said above and because I did my tunnings to an input of 200W rms, which is going to be where I'll be listening to mos. Sure I'll try full volume now & then, but often listening to music like that is not the case.

At 200W rms I tuned it to that the point at which the sub unloads and causes cone excursion to go past the Xmax is at 30Hz. The next peak of cone excursion happens at around 55 Hz and peaks at the Xmax. This also gives me some good freq response at 35Hz to 60Hz. If I wanted to go for SPL and general loudness, I could just tune it so the unloading point is at around 35Hz and the input being 400W rms. With this I could hit 130dB in the 50 to 60Hz range. Anyway, I still haven't finished the tuning.

One this I wanted to know is what port cross sectional area I should use and what port velocity am I supposed to shoot for?

Thanks,
Mike

Dukk

Try to keep your port velocity below 100feet/second

gtabmx

Thanks, I'll try to keep it below 30 m/s.

Also, I got a hold of some different material to line the inside of the box, two different types. Which should I use and how do I go about calculating the new apparent volume of the box to tune it properly?

I attached the pictures at different angles of the two materials. One is basically interleaved hemisphere peaks and valleys in a corrugated pattern, while the other is deep sinusoidal peaks and valleys in a corrugated pattern. I have enough of the hemisphere material to do the entire inside of the box, while I only have enough of the tall peak material to do two walls, and then the rest with the other. Or else I can get regular felt.

I feel the tall peaks will have much better acoustics.

Also, what exactly is the rule for computing the new apparent volume of the enclosure when lining with different types of material? I've heard of ADDING 10%-15% to the total volume or actually calculating the displacement and SUBTRACTING that or getting some expensive acoustic software to calculate. My enclosure right now will be 74.79L total, 72.63 L when taking into account sub displacement, and then less when taking into account port volume.

What should I do?

Thanks,
mike

gtabmx

Normally I don't bump, but I am about to stick this egg crate stuff in the box and I'm interested in some opinions.

Thanks,
Mike