95Honda

I hear you. I'm going on my 11th year of active duty. Every single one of my mid east deployments have been extended. My 02' in Oman went from 90 to 190 days... Like 15 days before we were supposed to go home... And that was about 6 months after they ended that $100 a day for every day over 179... Remember that crap?? They'd go broke doing that now... LOL... Qatar was another good one, started out as a 120, turned into a 175... Just like a week short of short tour credit... Oh well... I have a really good job now, NATO at Ramstein... 2E173, Ground Radio since 97', BTW.. -Mike Edgar

I'll tell you what, that is some impressive packing from Mach 5. I really like the way the inside was put together, there is some time and $$ in that.... All that leaves me to say is DHL/UPS/FEDEX a-holes really suck... I have been shipping these types of drivers going on almost 10 years now and it never ceases to amaze me the damage that occurs.... And it really makes me angry when I hear all the excuses like "Do you know how many packages a day we have to move".... Blah Blah Blah... Bottom line is, they just don't gaive a crap about our stuff... LOL...

The only thing that will determain hom many of these ports you will need is what drivers you choose. If you are sticking a couple of 12s in there that don't have much displacement than a pair of 4" Areos would be fine. But I assume that this may be for an 18 or a few 15s because it will be 8 cubic feet... If that is the case, you may really need 4 4" Areos or a pair of 6" aeros... So, figure out what sub(s) you will be using, that will determain the amount of ports (port area) you will need, the box size doesn't have anything to do with it. Why doesn't everyone use Aeros? They are great until you need a port that is 40" long, then they aren't so great anymore and you end up building the port out of something more practical. But for short port lengths, say 18-20 inches or shorter, they work pretty damn good. I have used maybe 50 or so... Quick and easy....

Uggghh..... I'm sorry you guys from FI have to deal with these types of questions in your forum....

Honestly, the only thing that determains the minimum vent area needed is the amount of displacement your subwoofer will have. I always wonder who made up the ratio of box size to vent area, it is pretty meaningless. Ok, here goes. You want enough vent area to keep the vent velocity (how fast air moves through the port) down low enough that it doesn't introduce a noticable amount of compression. This compression is bad because it will begin to alter the box response. The vent velocity is determained by two things and two things only, #1 the amount of driver displacement (how much the air the sub is moving) and the area of the vent. Box size has nothing to due with this, hence recomended vent area has nothing to due with box size. So, how does this relate to your question? Will a pair of 4" Aeroports work for you, in short, No. BUT, this is only if you are going to be driving those subs to full displacement. At this point a single pair of 4" ports will probably introduce a fair amount of compression and begin to alter the box response, and probably give a signifigant drop in efficiency over what the ported alignment should give. BUT, if the drivers are only driven to say 1/2 of thier full displacment, than a pair of 4" ports would be fine, but that is likely not the (your) case. Either way, 100in2 would probably be a little overkill, but nothing wrong with it. The best solution would be for you to download a copy of WINISD and start looking at the predicted vent velocity for the different port configurations you would like to run. I think (IIRC) it will give a recomended maximum vent velocity and you can see where you end up. You will also notice that if you change power input or vent area that the velocity will change, but if you change the box volume it stays the same....

Don't forget that for the same tuning, if you don't change the port area and you make the box bigger, the port gets shorter. It's a big box..... So, that may be part of the confusion.... OT, but West Indies? If so cool.... One of my best friend grew up there....

I think you should sell me your Qs and put a dead dog in your trunk. I'll have a nice pair of subs and people will be like WTF IN YO TRUNK MAN!

Bwahahah.... Kiss my ass Mike!

What is the most efficient subwoofer you guys build in your standard lines? Please, only someone from FI on this one.... -Mike Edgar

LOL....

You do realize that if you put one watt into an SSD and a BTL, the BTL is louder, right? And at 10 watts, and at 100 and at 500? With the same enclosure alignment...... The efficiency rating the manufacturers gave the subs was at 1 watt, not the RMS power... Stiff spiders and all, the BTL is still the most efficient sub out there (from FI)... It is a db or so higher than all the others... But, like I said it is a dead horse at this point... I think I'm done attempting to explaining this...

If you have a computer, I would really suggest buying something like the Parts Express Woofer Tester. This can give you a real impedance curve, an impdeance curve of the whole she'bang..... The accuracy of a clamp meter can be sketchy with reactive load AC (back EMF pretty much f*cks the readings up on the cheap ones) and my not be the most accurate way, that and you have to make about 100 measurements, all the while double checking to make sure the drive voltage is EXACTLY the same EVERY time (when is the last time someone really did this right?)....

Sounds like a solid plan.

Yes, you can find a volume that resonates easily, and this is sometimes near driver Vas. If you get a chance, do some reading on RF tuned cavities, helped me understand resonance very well... It may happen that this resonance falls in line with all other factors increasing overall system efficiency, and sometimes it may not (like if it is at 20Hz, LOL!!) Really, there are so many factors, what works for one may not work for others, I guess if it was textbook easy all the time, it wouldn't be much of a competition then, would it?

I honestly think there are too many variables for a firm answer on this... There are so(!) many factors that can determain impedance (saying "rise" really isn't accurate, because it dips alot also) it would be tough to coorelate box size with impedance curves in some kind of repeatable manner. Impedance usually varies alot depending on how much an alignment can readily (or easily) achieve resonance, or how under-damped it is.... And this can be real serious with big boxes also.... Also, when we talk about impedance, DCR (what you read with a DMM) doesn't mean a whole lot... When a sub reads .7 on a DMM, there isn't an amplifier in the world that will ever, and I mean ever, see a .7 ohm load. This is impossible. As long as the coil has any sort of inductance at all (they all do, if they at least have over 1 turn of wire, so that's every single one) The impedance will ALWAYS be more than the DCR, I cannot stress this enough, and the higher the frequency, the higher the impedance will be (not factoring in system resonance wich makes it even higher) due to inductance. I think it is funny when I see people talkling about what a coil "really measures", because if you don't have an impedance bridge (or something similar), you are not really measuring anything that has to do with audio... I guess what I'm trying to say is don't get hung up with what your DMM says, it is good for checking shorts or consistency. But, for impedance, trust what the manufacturer specs out, they give you a much more accurate "average" of what the driver impedance will be. Thermal compression a big deal with 3 second burps? Maybe, maybe not.... But when you get into 1/10th of a db FTW, it's the small things that can make a difference...

could be. and i can't really argue with hoffman, but as i said, i've seen what would appear to be a direct contradiction. can't explain it, but the meter showed it. if i had ///M5's equipment, we could definitely find out what caused it. wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee -Word

Sometimes you may not realize it, but by going smaller you may have moved the box resonance closer to the vehicle resonance... Were as if you would have done the same by higher tuning in an even bigger box you would have also gained (possibly more) SPL... But honeslty, like I said earlier in this thread, there will be many examples people will have showing something different than what I stated... But as far as box alignments go, can't get around Hoffman....

There is no myth or mystery here. It's Hoffmans iron law of size, extension and efficiency. You change any one of the parameters and the others most change. The larger a box, the more efficient and the lower the extension. The smaller the box the lower the efficiency and the less low end extension. Any time you have to add more power because you have done something like make a box smaller, you have made the whole alignenment less efficient and due to thermal compression ( all else being equal) it cannot be as loud. There may be all kinds of examples people can give to say otherwise, but you can't cheat physics.. Many times if some goes with a smaller box and can get a higher SPL, it is do to another factor they aren't taking into consideration that they don't know about, and not becasue of the difference in box volume. Eventually you will get to diminishing returns with box size and a response that has too much ripple to listen to music with (in the case of ported). And with sealed alignments you can get a Q that is too low that most of us will find sounds lifeless with most music, even though we have gained a ton of low end efficiency. Finding the optimum size is a balancing act between this, extension and efficiency goals. Many times we disregaurd the efficiency goal because we have #1 a ton of power on tap and #2 drivers that can handle a ton of power.... 99.999999% of the time a (vented) subwoofer will gain peak output capability with an increase of enclosure size, all else being equal. Additionally a sealed subwoofer will gain low end efficiency and play as loud with less power with an increase in enlosure size as long as the Q isn't signifigantly lowered (like less than .5)

You know, I have been thinking about trying something different for the sub stage also.... It's not that I don't love the XXXs, I will never part with them... But I have had the same sub stage since 05' in there... My thoughts were some of the new Dayton 15HFs. I can get those shipped to me for under $100 each, I was think of doing 8 of them, two boxes with 2 pairs isobaric in each box. The boxes could be pretty small that way... Just a thought though..... I dunno....

Dude, I love watching that wall. That thing looks wicked... Makes me really miss how much fun the Durango wall was.... If me you and Marshoo lived near each other, we'd be in soo much trouble man... LOL... -MIke

Active can get expensive depending on the number of bands you choose to go with, espically of you end up go 4-way.... That is alot of amplifier channels... Or, it can be cheap... For my dad's truck I bought the 2XS off of JBLGeo who used to post on CSO for $40. I cleaned it up and made a bunch of plug in modules from parts on hand.... The more you plan, the cheaper the execution can be...

1/4" aluminum plate, cut on a CNC. Made them myself.

Correct, for achieving the "loudest" sound. You can always upgrade power if you want it louder...

I ended up going active in my dads truck using an Audio Control 2XS. SQ is awesome and I love the flexibilty. These have the plug in modules (you solder resistors onto little 16 pin chip holders) so you know your frequencies within a few %.... A little more complicated, but worth it if you see it through.

You know, thats funny, the pieces of mdf never looked big after cutting them up either (or when I designed this on paper), until they were all put togther... And I had to move them around... I'm 6'2" so you can kind of get an idea for size of the boxes....