95Honda

That's the thing, your not using re with test tones, you are using impedance. It doesn't change .000001 percent, it changes 100%-1000% over the range the enclosure is designed to operate. So if you use any methods that simply assume an impedance, you aren't a little wrong, you are a lot wrong... I am stunned JL even publishes that info. The only way this method will work is into a non-reactive load. There isn't a subwoofer made that is non-reactive.

^^That and the fact that a DD-1 (or any test equipment for that matter short of a servo system) will not keep you from mechanically damaging a driver...

None of those methods are reliable...

There is a difference. 4th order has nothing to do with being a bandpass. It has to do with the enclosure roll-off. I haven't built a blow through before, but if you design the enclosure right, it shouldn't make a huge difference in output regarding how you route the vent into the cab. One thing to remember, the less turns the air has to make to get through the vent the better.... I have however built about 20-30 4th order bandpass boxes, so I know a thing or two about them...

Bandpass or conventional 4th order vented?

Hey, try and check those Crowns out at a music store before you buy one, just see how loud the fan is... They can get annoying... As far as using a pro audio amp, the input line voltage is the same (120V AC). They normally have balanced audio inputs, which isn't a problem for most home audio gear to drive as the input impedance is still faily high. If that Crown only has XLR inputs, you just need to make adapter cables (pin 2 connects to the center of the RCA plug and pins 1+3 are tied to the shield/outer conductor of the RCA plug) The amp will have adjustable gain, you will be able to drive it to full output with just about anything. Unless your current system has a low-level sub out, you'll want to get an AVR that does. Most new ones do. Most also have an LFE channel that has a crossover and EQ built in, so you just run it into the amp and go... That is the easiest way. If what you have doesn't have any processing/crosover, you can also buy a dedicated sub amp that has crossovers and EQ built in. Partsexpress sells a 1000 watt unit that has no fan, corssovers, eq and auto turn on. I think they are around $400. I have used about 10 of them and have been happy. If Thilo designed those boxes, I would stick with them. Hope this helps.

If a sub bottoms out it is your fault. You will more than likely will end up breaking any sub you buy. Good luck!

Most new factory headunits begin to roll-off the lower frequencies as you increase volume. This why LOCs like the Audio Control LC2i have EQ that counter this... I have just never had good luck with PACs in the past...-

Hmm, something sounds funny then... Couldn't tell you more unless they changed the design somewhat...

Hey, just looked and I couln't find an option for a dual 4 SP4. So if you are truly reading 2+ ohms DCR per coil, something is funky... I know you have done this already, but are you sure you are reading one coil at a time? If you read both coils in series, you may end up over 2 ohms..

Did you set up the LC2i according to the manual? I have one but haven't set it up yet...

I used to swear by a mirror smooth finish inside, but the more research I have done over the last decade has lead me to the conlusion that a smooth surface is actually more turbulent overall inside the cabinet than a slightly rough one because of the small turbulant boundry of air right on the surface that keeps everything else flowing smoothly... Look up Laminar/Turbulent/Seperation and maybe this will help... Just a little food for though I guess...

lol. You broke 158 with a pair of 18s and roughly 3 times the rated thermal power and want to get rid of them now... A recone(s) is going to be a fraction of the price of new sub(s).

Impedance comes from the reactance to an AC signal. It changes with frequency. DCR is a measure of DC resistance. Not impedance. The impedance rating given by a manufactuer is an average. You cannot measure impednace with a DMM because it will only measure DCR, unless you use it in conjunction with other test equipment. Impedance is also heavily affected by your alignment, actually moreso than the driver's average impedance on it's own...

Sounds like you have a dual 4 ohm coil SP4. **EDIT didn't realize this wasn't an option** Just remember, you cannot measure voice coil impedance with a single DMM. You are measuring DCR, which is much different...

Doesn't smell so bad now... Whatever solvent is in that stuff is nasty... Doesn't really help that there is a gallon in there also... I like this look and have been doing it for some time now. It makes for a clean and tough enclosure... I tend to do this design for removable installs, which I do more than permanent really...

BTW, that VBX-1 smells like shit. It has been about 12 hrs since I sprayed it, it is 90 degrees out todat with 10% humidity and it is still outgassing like a motherfucker, lol...

Assembled and ready for Line-X... The grill is just sitting there on some paint can caps, my hardware order still hasn't shown up. I sprayed 1 gallon of deadener inside. I sprayed it during different stages of assembly, so every internal part is coated, even the inside of the vent on all portions. You can see some of the braces, the vent is also braced, it is actually 2 vents. The box is heavy, but not super heavy. I am glad I dado'd the baffle in, that Mayhem is heavy and will be moving around alot... This box should never come apart... So, I ended up using 1 and 1/2 sheets od MDF, 1 gallon of VBX-1 deadener, 1 pint of polyurethane glue, some bondo and a ton of T10 torx deck screws, maybe about 150. Every joint is screwed heavily. All joints turned out real nice. When the Line-X goes on it will make everything flawless, looking forward to getting it done...

Most of the pieces before assembly... Tough to see on the bottom piece, (the rear piece) but it has all the recesses for the rubber vibration isolators. There are T-nuts behind and the isolators thread in and mount the electronics perfect, about 1/4" off the box...

The RMS rating has absolutely nothing to do with how much a driver can handle in any particular alignment. It also has nothing to do with how much power you should have/need. A little food for thought...

Man, I know right... I better do some research next time...

Please don't follow any of the advice in the last 2 pages besides BKLOFO4s.... Enclosure size effects efficiency, the smaller the enclosure the less the efficiency. Port size doesn't effect "Back Pressure" if it is acting as a port... Nobody runs 3X RMS power continuosly. They think they do, but they don't. If you bottom out a driver it is due to reaching the power limits of the alignment, there is nothing wrong with this. If you make the box smaller and it handles more power, it won't be any louder than the larger box with less power. You are just turning more power into heat instead of acoustic output.

I also made a $40 order to Fastenal. All hardware will be black oxide, including the washers. I ordered specific fasters for each application so it will look real nice when finished... I am heading to San Diego for work next week, will get more done when I get back...

OK, started cutting some wood today. Got the basic parts done, the bracing will take another 1/2 day or so to cut. I decided on a 1.5" thick baffle that will be dado'd into the top/bottom/sides for extra strength. All wall will be effectively braced and there will also be a large center partition brace. I will also brace the vent. So, here is the baffle being bonded before being cut to size, siting under about 500lbs of Zombie Prep materials: Here is the cabinet just sitting there to get an idea of how it will look. The grill is jst sitting there with some wood shims holding it in place. There is a 1/4" gap around the edge that will be less than 1/8" once the Line-X is sprayed. Also, the grill isn't exactly flat as it isn't bolted down to the stand-offs I am building. To give you an idea of size, that is a 18" x 28" grill. It will sit flush with the front, the baffle will be 2" behind it with the woofer countersunk flush...