95Honda

Yes, a true T-line should at least have the line equal to Sd at the termination point. It isn't practicale to start with Sd because unless you are using a tube, it is impossible. This is why they are tapered to a point, usually they start out at 1.25X Sd and terminate right around Sd. T-lines don't have tuning, in fact they are very non-resonant. They have a cutoff frequency that is determained by line length and stuffing density. 6 feet of length gets you roughly around 30Hz or a little lower. The stuffing supposedly manipulates air velocity in the line and dampens resonance, usually you stuff heavily at the beginning of the line (1lb per ft3) and gradually taper to little or no stuffing the last foot or so. You stuff accordingly to smooth the impednace plot. I have built maybe 10 T-lines, all have been stuffed with Dacron or Acustastuff, every one I have seen is also stuffed. Most modeling uses stuffing. A port calculation has nothing to do with a T-line. T-lines are not for SPL. If someone has a T-line for SPL, 99% it isn't a T-line. They are non-peaky (little ripple) by nature and will not exploit the driver with huge Fr peaks if done correctly. A perfect texbook T-line would be you woofer attached to the end of a 6-8' piece of 15" diameter sonotube with about 6-7 pillows worth of stuffing inside, maybe this will help you visualize what a T-line really is, and why they are impractical in a car if they are true T-lines... Hope this helps...

Actually, you didn't built a transmission line. With the size of that rear chamber and the the size of the line, you ended up with a very low tuned ported box. The line needs to be roughly the Sd of the driver. The rear chamber needs to be as small as possible, idealy it should just be the begining of the line. Most TLs use stuffing to flatten the impedance/behave appropriately.

What didn't you like about the Alpines?

I never noticed that any of thier wire was copper clad aluminum, if that is the case, you can't even compare it. Aluminum (the cladding doesn't really amount for anything as far as DC current carrying capability) wire is much less efficient at current transfer than copper, especially at the amperages we use in car audio. Copper has roughly 1.6 times the current carring capability vs the identical cross sectional area of aluminum. So your 0 gauge Aluminum is equal to roughly 1 gauge copper..... Think about that... Aluminum is cheap, light, strong and deals with heat well, but as far as wire performance, it's way down on the list... If you are getting all copper stuff for around the same price as welding cable, then that is a decent deal. It will never have the same performance (insulation), but amp for amp will carry current just fine. I guess what really makes me go WTF is when I see things like pre-packaged Stinger 1/0 for $140 for 25'..... I just don't get that at all... The purity of copper is thrown around alot (like 99.9999 or "6-9s") but for power wire everything made we can buy is pure enough to do the job well... As far as signal goes, there can be audible, even measurable, differences. But for most of us, these differences aren't worth the extra money they cost.... The extra "grounds" you are talking about are shields on some cables. They can cut down on noise. But watch it, alot of them are used for looks/marketing ploys, so buyer beware!

The outer shell of EVERY RCA connector is signal ground. It is either tied to the chassis/earth ground OR to circuit ground (floating) at the equipment.

This is exactly why I always say it is in the install and very subjective.

Have you ever used welding cable? You can tie Suplaflex 4/0 into a knot that is about 4" in diameter, do you understand how flexible that is? The 1/0 is a few thousand strands. This type of welding cable is more flexible that most "car audio" cable.... I am not sure where you aren't understanding that this is the best (most constructive) advice there is for power cable, unless you want to pay for looks... People tend to have negative opinions about things that are a rip-off. It is probably easier to buy welding cable, from a computer, with a credit card than most car audio sites....

How long is your line? Did you use any stuffing? Did you measure impedance? What cross-area did you terminate with?

If you are trying to build a box to handle the maximum (mechanical) amount of power then that is easy, 1ft3 sealed for each driver. They will handle 10,000 watts. If you want to design a box to be the loudest, then you design the most efficent box you can make in your targeted bandwidth (sounds like 30-40Hz in your case) within your size limitations and apply all the power you can until you reach the mechanical limits of the drivers, and hopefully this is before you reach the thermal limits, at least on an intermittent basis. It sounds like you already have enough power to take those drivers to thier mechical limits in just about any ported box, so this should be pretty easy. The logic of the OP was backwards, the question should have been: "What is the most efficient enclosure for 4 BTL 18s that is within XxXxX dimensions, I plan on playing music with this, and will 24Kw be enough for it"?

I don't care what anyone says, a smaller box will never be louder than a larger box unless you are talking a much higher frequency (seriously higher), it's impossible. I know a bunch of people may argue this, but it is plain hoffman's iron law. Many times people make the mistake of saying the smaller box was louder simply because they changed something else irrelevant (like the amplifier being more happy with a new impedance curve) or they have just moved the alignment peak closer to the vehicle's resonance. Additionally, if you have a smaller box and tune it drastically higher, than it will peak higher than the larger box tuned lower. BUT if you tune the large box as high as the small box, it's peak will always be higher. Period. Model any sub, make the box bigger and watch the peak... The whole port area vs box size is completely faulty logic. Port area is soley dependant on driver displacement, tuning frequency and power used... In the big scheme of things, box size plays a very minute role in this... The only reason many companies do (publish) this is because they know people will put their BIG subs in BIG boxes and will need BIG ports to keep compression to a minimum. As far as which one will be louder? Model them and look at the peak in Fr, more than likely, which ever one has the highest peak will be loudest, assuming the peak is around the vehicle resonance...

If you buy anything other than Supraflex Welding Cable for power wire, you are pretty much just throwning away money... And buying wire that isn't as high of quality. People are smoking crack if they think getting 20 odd feet of 1/0 power cable and a few accesories for $140 is a good deal... I can get 20 feet of 4/0 (0000) for that price and ring terminals.... I prefer Dayton speaker cable from PartsExpress, I don't think you can beat the price, they go all the way down to 10 gauge. Pretty much all the car audio speaker cable is way overpriced, especially the ones that are twisted and have an additional PVC outter jacker or tube (Stinger). Again, I would be willing to bet that no car audio company could come close to the Dayton line of interconnects. They have some of the best quality connectors and wire I have seen below a few hundred dollars. You just can't get real short stubby RCAs from them, and I know sometimes you need that. As a side note, if you are buying interconnects, and they are RCA type, and the word "balanced" is anywhere in the description, you are paying for 100% BS. There is no such thing.... But, if buying from Kicker, Knu, etc makes you feel better better, do it, because the good feeling is all your gonna get....

The sound is 99% in execution. You could easily make any of those subs sound terrible. And you could easily make them all sound great. It is all your enclosure, install and vehicle. That is THE answer. You will hear all kinds of opinions on the subjective sound quality of the listed subs. But you also need to understand that the right person could make the worst "sounding" sub in that group (worst Fr, highest Le, worst Bl curve, etc) sound better than the average shop could make any of the others sound....

The help will reflect the quailty of your post.... So don't expect too much....

Max- I am using a pair of the XX18s in my home setup. You can really do good with these types of drivers in home audio due to lack of space problems for the box. Another nice thing about home applications is you can go big and efficient, so you don't need a ton of power... I was running about 5,600 watts RMS on my 18s, and am now only running 800, and they still sound really good. The Q's would probably work great, there are really a ton of options out there for H/T applications though. I have built at least 50 subwoofer systems for home audio, many using "car audio" drivers... http://i304.photobucket.com/albums/nn183/M...lEdgar/2ch1.jpg I am in Obermohr, about 15 Kilometers from you. -Mike

I think he should get the 18!

Absolutely correct.

You know the cone never makes an immediate stop, at least not the majority of it. As far as swept air, I'd be willing to bet that, beyond the scope of reason, this could never be shown to increase cooling effectiveness, at least say above a few Hz or so. The cone still moves back and forth the exact same amount with a square or sine wave, maybe even more with a square wave giving even more effective cooling. I wouldn't be able to say if this makes a mechanical difference or not. Many voice coils are rated at 1khz anyway..... I think clipping is used as a reason for failure, it seems logical at least. My test took 20+ drivers and proved this, I have the knowledge and had the proper test equipment at the time. An HP Distortion analyzer, a $2K current probe, etc.... I still think the effects of clipping are way over touted, there are literally 100s of 1000s of guitar amps to back this up... Honestly though, I would never expect anyone that sells drivers to say clipping was a good thing, I certainly would not....

That is where many people get confused. When you look at normalized voltage, of course there is more power, this has never been a debate. But if you look at the watt per watt failures between square and sine, there are almost identical. This is because power is power, the sub doesn't care if it is a square or sine. If the sub will handle 500 watts, it will handle 500 watts of anything you put in, as long is it isn't long term DC and have no cooling from cone movement.... Clipping has never blown (thermal) a driver. To much power does, that's it. A driver will blow just as fast with a 1000 watt square wave as it will with a 1000 watt sine wave. You could have your headunit totally clipping, say full THD, as loud as it will go, just raping it..... As long as the amplifier never puts out more power than the sub is rated for, this will never cause damage. The same is true for running an amp into hard clipping, as long as it isn't putting out more power than the speaker is rated for, than it will not harm the speaker, unless the manufacturers are exxagerating the power handling claims. You have to think about guitar amplifiers to help understand this. They can run upwards of 30-40% THD to get the sound they want.... And the drivers last 10,20 even 30 years..... With a decent amount of power running through them. If you listen to any electric guitar music on your system, and there is any type of distortion/overdrive being used, then clipping (severe clipping) is being played through your system.... If you have your system so tapped that you are continually blowing subs due to what you believe is inaudible clipping, than you have serious problems. When clipping becomes severe enough to raise your amplifier output to a level that can cause damage because of power increases, and you can't tell by listening, you should find a better way to spend your money... Some people will get this, some won't...

Clipping doesn't hurt anything. Please read this before you respond to this statement: http://forum.carstereos.org/clipping-test-...41.html?t=47441 Yes, I suggested the 18 because he would more than likely ask too much from the 15, and blow it.......

There aren't any "sound" differences between a 15" and an 18". The differences are in the box alignment and loudspeaker parameters. Use an 18, you'll probably just blow the 15....

If the signal comes from the front speakers, you won't get the feedback anymore, but you'll loose fader control if that matters to you... An alternative is to place a high-pass filter on the rear speakers, and make sure the LOC is taking signal before the filter. A 50mfd cap would be probably fine, just put it in sereis with the speakers as close to the terminals as possible. This will add attenuation to the driver near the feedback frequency and will more than likely help get rid of the loop. I have had this happen to me twice, both with subs in the trunk and the LOC hooked up to the rear-deck speakers. On one system, if the trunk was closed it howled like mad. I tapped of the front speakers instead. On the other system, it would get feedback occasionally, so the highpass filter worked fine for the guy.....

but a Vifa ring radiator and midbass are a lot less expensive at Madisound and you don't get passive Xovers that'll be useless to you. I completely agree. I have been putting together component sets for car audio maybe for, I dunno, at least 15 years. I spent the 1st 10 years designing really, really nice passive crossovers, but it took alot of work. But, they always sounded much better than anything you could by at several times the price. I remember putting many sets of components that used the 90K Focal Kevlar tweeters when they were $40 a pop at Zalytron and mating them with Focal or Scan Speak mids.... For a few hundred bucksthey were awesome... I probably designed 20 or 30 sets over the years.... About 5 or 6 years ago I started playing alot more with active setups, mostly because decent 4 channel amps have gotten alot easier to find and pay for. Really like outboard crossovers that have exact frequency selection, like the older Audio Control stuff with plug in modules, I mean I could find these for $25-$50 used on e-bay. I know there are a ton of outboard processors out there, just look for decent filter control, not just a dial with a vague idea of where it actually is set. I would really shy away from using any built in crossovers inside the amp unless you are using it as a highpass for the midbass low-cut. As for drivers, you would be amazed what you can get for the money, I say it often, but the hands down some of the best drivers you can get for this application are the Parts Express Dayton reference 4ohm drivers. These sound, and measure better, than almost anything at 3-4X thier price. They are pretty cheap, only around $40 each. Mate these with a decent tweeter like one of Ring-radiators Jim talked about and you would have a serious kick-ass set of components. The last set I put together was in my Dad's F-150 and this used a set of the 6" Dayton references combined with the 1" Vifa Neodium tweeters. He is running a 2XS and an older 100wx4 Rockford Punch Power series amps, it absolutely screams, sounds really, really good and was fairly easy to set up right. He lets it eat, and I mean LOUD, on a daily basis and they have stood up no problem over the last year. The really nice thing about active is you don't have to worry about driver impedance/filter network interaction. This is a HUGE help. No Zobels, no traps, no EQ, no L-pads.... It really makes things nice, especially if you are a novice with this stuff. I really think you would be very, very happy with an amp like a 100.4 you are looking at and a set of decent midbasses and tweeters like Jim and I are reccomending. I would be happy to help off line with driver selection and frequency selection. -Mike

If this is for your backpack, I would try something really cheap for an amp. Just pick up a $50 legacy/pyramid. If you mess something up then it will be no big deal, or if it gets stolen, etc.... You can easily get an honest 50 watts or so out of these amps and that would be plenty for your backpack. If one of those batteries isn't enough, just add another. Honestly though, the Tangbands are pretty inefficient drivers. I would look into maybe a single 8" driver with a little more efficiency and I wouldn't worry about the stroke of the driver so much. Look maybe at some of the Parts Express DVC 8 subs, I think they are about $20 or so and will work in a pretty small box, or even easier maybe a 10-12" section of 8" PVC/Sonotube.....

3 4" Aeros aren't choking it, you probably wouldn't notice much difference if you added 1 or 2 more, you didn't do anything wrong here. Honestly, I wouldn't beat around around the bush if an 18" sub isn't enough, I would go with at least 2 15s or another 18 if possible. Like others have said, a little higher tune may help also...

Actually, power handling may be much more affected by the alignment you choose, rather than the "BP" option. If you choose an alignment that will get full stroke out of your driver with most of the music you listen to with a given amount of power, well, then adding more power is stupid. Saying a driver "Needs to get it's RMS" is really a dumb thing also, since the RMS power handling and power requirements have absolutely nothing to do with each other. 1000 watts is more than enough for any subwoofer to perform well, especially if you know what you are doing.