95Honda

Nothing to do with either. The length determains the cutoff, that's it... Read up on Martin Kings (www.quarter-wave.com) white papers, you'll save yourself alot of time and headache. Additionally, diysubwoofers.org has a short, yet to the point explanation of a T-line. To be honest, most "T-lines" you see here, or any car audio site for that matter, aren't T-lines at all....

The speaker cabinet carpet (non-latex backed) like Partsexpress sells lets you hide the seams flawlessly. If regular automotive carpet is used, no matter who installs it, you will always see the seam because of the directionality of the carpet fibers, where as the speaker carpet has a random fiber that goes all over the place and can blend together. Super 77 is OK, but if you want carpet that will not come up, regular DAP Weldwood liquid is best (unless you have a gun that sprays the industrial stuff). I use alot of this, roughly a gallon for a 8-10 cubic foot box, you need to be liberal. And it won't soak through the speaker carpet even applied this liberal. I use a paint roller. Put at least 2 coats whereever there is MDF endgrain, as it will soak up the first coat. I have carpeted at least 100 boxes this way. I have seen some of mine from 15 years ago, to this day the carpet stays on strong and the seams don't show...

You can do alot with them, really... The last 8s project I did as with 8 RE8s. They did 143db on the termlab with 150watts total.... Most people don't do that with 1000 watts it seems... So I guess what I am trying to say is, you can get really loud with 8s if you build the box right... The getting low part has pretty much nothing to do with the size of the driver, it is much more dependant on the box and T/S parameters... Aditionally, 12 8s will give you a ton of thermal power handling... Much more than most pairs of 15s so you won't have to worry so much in that department... With a 3000d, all else being equal you'll have roughly 250 watts a woofer, should be plenty but not so much to get you in trouble....

Class Ds have similar efficiency, at least close enough to not matter (we are talking with 10% or so). Bottom line is, the more power the amp, the more power your electrical needs to supply, regaurdless of amplifier type or make. And what is to the max? Until they blow? Nobody can answer this for you without enclosure details.... A BTL could reach full output with far less power than you are talking in the right box. Additionally, there is no such thing as underpowering these (or any) subs. If you have 2 BTL 18s and only 4-500 watts each, they will still be louder than just about anything else.... If you have a few thousand watts each they will be louder, of couse, but this isn't mandatory. Additionally, once you get to a point where thermal and mechanical compression sets in (not much over 1000 watts) your returns on adding power exponentially decrease.... To the point of equalibrium at thermal failure....

Yes, it is from induction (inductance) and it becomes a problem when you take a 10" driver with a huge, long coil with tons of Le to get massive stroke and handle tons of power like Bob Carver did with his little sub. With XBl2, Underhung and other low Le, linear drivers, it isn't hardly an issue... Additionally, the subs like the BTLs are very efficient and don't need a lot of voltage to make bass... Drivers like a Solo-X and other purely over-hung motors with tons of X-max and huge, long heavy voicecoils have tons of Le and back EMF can become a considration... Back EMF also isn't an issue if you don't put your driver in a box so small and innefficient that it takes 2,700 watts to get it moving to full stroke....

There isn't much you can do about the group delay. Does your program show it? If it does, see how bad it is and if you can manipulate it much with tuning variations... If you look, you'll probably have 2 huge spikes in group delay at the lower and higher tuning points, with a trough (of still high group delay) in the middle.... The lower end tuning will probably have more group delay, but it isn't as audible down there. Where it gets annoying is 40Hz on up... Near the upper end of your pass band (drums, bass guitar, and such) you may get the results of muddy or sloppy sounding bass...

I have tested the following P/E plate amps into 4 ohm resistive loads- 250 watt plate amp, (the $135 one) 271 watts @ 4 ohms before visible clipping... I have used maybe 10 of these... Talnlanky's amp was the last one I tested... 1000 watt plate amp, 1003 watts @ 4 ohms before visible clipping 500 watt Bash, don't have anything written down, but I know it made its rated power before the onset of visible clipping... I can't vouge for any of the others.... I think sometimes people say they don't make rated power because of #1 sagging or low AC mains or #2 innacurate output measuring technique... All the P/E amps except the Bash (IIRC) have linear power supplies, if you don't have at least 120V of AC, they won't meet specifications.... I use a 2.5Kw variac with all my bench testing and set it for exactly 120V.

Then it should be fine. What most people don't realize is that there are literally millions of drivers being used this way right now. For those of us around during the single pasive sub and sattelite craze of the 80's and 90's (before power subs became popular) we have seen this before... In this application you often had a single dual voice coil driver having each coil driven by the left and right side of a 2 channel power amp. This would be two different, often very different signals. There has never been a driver that was destroyed because of this. Seriously, I think that everytime someone says the signals have to matched has no idea that this has been common place for so long....

It is the difference in time the different frequencies get produced (arrive) by the alignment, the more group delay you have, the worse things sound. Some people would call this transient response, it technically isn't, but you could describe it that way.... Group delay tends to be worse right above and around tuning, so thats two strikes against a 6th order right off the bat....

6th order vented tend to have pretty bad group delay.... One reason why Bose subwoofers sound so horrible... It would (could) be very, very loud though... You could use some FMODS, or even a passive high pass filter if bottoming out really became a problem... I have built a few 6th order BP boxes for home audio, I like 4th order better.... I copied that stupid Bose bazooka 12" sub, it sounded like ass but was loud...

I pulled them out of my rear-end.... Just as all peak ratings are....

I won't hurt anything. You just have to make sure they run out gas at the same time. If you have one that say starts running into clipping at 1/2 volume on your headunit, and one that does at 3/4, then it will start sounding like ass at 1/2 even though the other amps has some left in it. This is where you would want to match voltage if you could.... Now additionally, remember how I said the phase differences cause cancellation? Since those 2 amps are completely different, they may have signal processing (boost, X-over, etc) That introduces phase changes. If you have enough phase differential, your losses from cancellation could be greater than what you are getting with your power gains. So, unless you Really, Really, Really know what you are doing, it might not give you the results you are looking for...

I think most of it has do with the IXL's larger Vas, everyhting else being somewhat equal, this is where your efficiency boost is coming from...

What standard? I know they are at least 10,000 peak at 125ms, 20,000 peak at 62.5ms....

There isn't much too it really. There is a magnetic field generated by the coil. The more the current flows in the same direction through the wire in the coil, the greater the magnetic field. The greater the magnetic field, the more the cone moves. You could break the coil into infinite sections (like dual or quad coils for example) and feed each section current, as long as the current is going in the same direction (amplitude does not apply in this equation) it builds the magnetic field, it builds it additively. That's about it really... The voice coil windings can't "fight each other" because there is only one magnetic field generated, not two or more fields... If there are different phase relationships you will have cancellation, that is it. But that isn't ever the issue with matching different drive levels... The cancellation only lowers efficiency anyway. It doesn't cause overheating (we are talking only a few degrees of phase here) or anything wierd.... You won't ever have serious phase issues anyway, unless your equipment is broken. Even then, it still won't cause any damage unless you seriously try to.... People have made this up. Nobody has ever blown a subwoofer any faster because of different driver levels to individual coils.

This is 100% a myth. The outputs never have to be matched when running seperate coils with seperate channels or seperate amps. Either way you want to do this is fine.

What voltage and current did you measure right before clipping?

If it isn't an impedance matching issue, strapping two amplifiers together will never give you the same performance as running them unstrapped. Any time you bridge (strap) two channels (amplifiers) together you cut the amplifier's dampening ability in half.... Other small, but noticable performance reductions may happen. The ONLY time you should ever strap amplifiers is if your loudspeaker impedance is too high to get the power you want from the amplifiers when operated independantly... I think alot of people missunderstand this....

Yes, yes and ...... yes....

Actually, you can put "oversize" wire of any gauge into most loudspeaker terminals. You can buy solder/crimp-on ferrules that will reduce the end of the wire to a usable size. They make these so you can fit a 4 awg wire into a 10 awg terminal, for example... No, I don't have any links...

You can't hurt a BTL with a home reciever, at least not one that I have ever heard of. You may hurt the home reciever if the BTL impednace is lower (very likely) than the minimum of your reciever (usually 6-8 ohms) I don't know why you would do this unless you are running a passive crossover and running the highpass to your mains and the lowpass to the BTL voice coils..... Again, beware of minimum impedance.... If you had say a dual 4 ohm BTL (do they even make these?) and a reciever capable of 4 ohms, you could build a killer sub/satellite passive system with a BTL in a big box... Would probably be louder than anything passive you could buy sans a horn-loaded sub of some kind....

You could never run 8 gauge to the coil directly, you would trash the spiders, ruin the wire and have lead slap like crazy. It is just way to heavy and not flexible enough... If you want 8 gauge to the tinsel leads, like DD does, just solder them on yourself. It is a waste if you can get 8 gauge into the terminals anyway, you could't hear or measure a diference between soldering them on or a proper terminal application....

Welcome! And hello from the Pfalz...

#1, it doesn't matter what your gain setting is, you can always get full power out of that or any amp #2, you can ruin any sub talked about here with that amp #3, every signgle 18 on this site can handle that amp if you are carefull So the moral is, there is no correct answer to your question. Nobody knows how much power that amp will put out in your particular application. Buy your sub, build your box and use your head and you will be fine.

I guess I don't understand the connection you are trying to make. His white paper has little to do with the bulk of high the efficiency, large motor subwoofers discussed on this site (BTL, Havoc, etc). You also know that Bob has a way with words, right?