95Honda

#1 The morre power you get, the louder you can play until you blow the sub #2 You don't need electrical upgrades to run any amplifier, you need an electrical upgrade if you will be consuming more wattage than your stock electrical system can produce.... And this has nothing to do with the type of amplifier or how large it is, it depends on how much power you ask the amplifier(s) to produce.. #3 There is no such thing as underpowering.... Ever... Some tool made this up... #4 You get what you pay for.....

You'll blow the sub.....

If you can't find something that is 2 ohm, just try and find something efficient...

How could you ever blame anyone but the guy controling the volume knob? LOL.... Seriously......

Looks good! Man I bet it's a bitch getting those top 2 in.... I broke a toe on my right foot mounting a XXX18 in a nissan sentra while trying to get it in to an angle like that... LOL... Also nice to see panels actually fit together nice in some place other than the Fisher customs section... LOL...

Is the amp running out of gas? If the answer is no, you can keep turning up the gain until it does, then don't go any higher than that.... If you can't tell when the amp runs out of gas, set the gain wherever you want.... And buy an extra woofer... It is that simple... Seriously.... You've wasted a bunch of your time already... Quit and enjoy your music...

Funny thing is, port area has nothing to do with box size... At all... This rule of thumb was made up to keep stupid people from putting 2 18" subs in a box with a single 3" port... So in other words, you are probably fine.... If you are worried about it, run your alignment in a modeling program with your amount of power and see what the vent velocity is, if it is too high, then yes, you may need more port... But again, relating port area to box volume is horse s*it....

There is nothing wrong with them there, as long as you force air through with some fans. That location (with forced air cooling) would be better for the amps than mounting them on any of the walls of the enclosure...

If you are on a budget and want a battery, go to walmart and buy the biggest one they have. They have some that are over 1000CCA for around $100. You can take it back as many times as you want also, LOL!... And honestly, most people could never tell the difference in performance vs a $2-300 "car audio" battery.... They are just big and weigh a ton, that is the biggest downside I've found......

Every car (and home) audio amp made has some Chinese in it..... No way around that for the last 40 or 50 years....

Clipping has never blown a speaker. Only too much power has. That is it, as simple as it gets. Unless you have done an objective test with this, like I have here: http://www.forceaudio.com/showthread.php?t=15 You probably don't understand what is really going on..... If you aren't sure how to tell if you have too much power, either a) get less power -or- b) buy extra woofers..... Setting your "gain properly" is a load of BS, IMO.... Using an O'scope is a complete waste of time and gives you nothing but a false sense of security.... Bottom line is, if you can't tell when you are blowing subs, and you actually care, then you need to have less power on tap or find a different hobby.... You can't blow a 1000rms speaker with a 500 watt amp (within the general realm of sanity) unless either of the manufacturers have lied about the specs...

There is no such thing as "underpowering". There never has been and will never be. It is one of the biggest missconceptions in audio....

I have built tons of boxes without any screws. I mostly use biscuits though, it you are only doing butt joints they are the quickest and strongest. I only use polyurethane with MDF. Mostly Elmers. I haven't used titebond or others for years. It takes alot longer for poly to dry, but I think it is a real step up in performance. If you are going to have it sprayed with liner, prep it like you are going to paint it. I have done about 50 or so boxes sprayed with line-x that last few years. You can see a finish nail hole if you look close enough.... This box is line-X'd. It is also completely done with biscuits. All 1.25" MDF.

You don't need anything special for the car. A 1/4 wave t-line is the same for either home or car. The only difference is you may not need such a long line (low cut-off) in the car due to cabin gain. A 6' line will do fine in a car, reach well into the low 30Hz range. I have built a few for car audio, none over 6' long. There are a few things you need to understand about 1/4 wave t-lines: They won't be any more (average) efficient than a 4th order vented alignment, the only efficiency gain will be way on the bottom end... They are usually less efficient than a 4th order vented above the F3 of the vented alignment. T-lines are large. If you build a 6' line for a single 15" woofer, the line itself will displace around 6.5 ft3. This doesn't account for any wood, unused cabinet space, etc. This no matter what shape you make the line..... T-lines are not peaky if built correctly and are one of the last alignments that would be practical (especially given the size) for SPL. T-lines are intended to be non-resonant, as opposed to a vented alignment. They are supposed to have a flat response. They will have a flat response if built correctly. They should be stuffed. With something other than Dacron. Dacron works, but I don't find it works as good as acousta stuff. If you don't stuff the line, it will not be well dampened and will need to be much longer. Like a few feet longer for the same cut-off. A majority of the line is stuffed. It is not stuffed for the same reason a sealed or vented box is. It is stuffed primarily to increace the effective length of the line by slowing down the speed of sound inside the line. T-lines should be tuned. This is done by generating an impedance plot and adjusting stuffing to get a flat impedance curve. This is easy in a sonotube. It isn't in a box. On all my t-lines I would leave one side of the cabinet only attached with biscuits, no glue. So I could take it off, adjust stuffing, and put it back (smacking it with a rubber mallet to get it to fit snug) and measure impedance. When I got what I figured was a decent curve, I put it on one last time with glue and clamped it in place. This worked well for me. So, for a short answer.... Build a 5-6' line that starts out around or a little more than the Sd of the driver, taper the line to terminate at Sd, stuff it with acousta stuff and measure it for impedance if you can. If you can't measure, just use some of the stuffing density reccomondations from Martin King, even Mahogany sound (makers of acousta stuff) have guidlines, but I haven't seen them for years. If you want something that is peaky and loud and not so big, don't build a 1/4 wave T-line, build somehing else. If you are looking for high efficiency, complicated designs, check out Decware or something like that....

This is the most ridiculous thing I have ever heard. If this was actually measured this way, whomever measured it had no idea what they were doing, did not understand average efficiency, or they had one (or more) driver(s) that were severly miss-aligned.

Additionally, the last thing a traditional 1/4 wave T-line is known for is being super super efficient. In fact, a properly built 1/4 wave T-line is well dampened, with a flat response curve and efficiency at or just below a average 4th order vented aligment. It just has a much a shallower roll-off with a more efficiency in the last octave..... This is why most "car audio T-lines" aren't... Alot of them are peaky 4th order vented alignments, some have horn loading mixed in, some even are acting as a banpas filter. Some (most) are undamped lines that people think are behaving like a T-line, but in fact if they even were, the cutoff would be an octave higher than they think. I have been building speakers, alot of speakers, since the early 90s. I have build a lot of succesfull 1/4 wave lines. I have built a lot of unsuccessfull 1/4 wave lines. Some of them turned out to be low tuned, ported aligments when the Sd of the line became to small, there was too much airspace and not a proper feedpoint to the line, they were undamped or they were to short. I have measured many of these, I even have a buddy who used to own MLSSA in the mid 90s, I did some tuning with him on one of his t-lines and saw first hand how these things work. 1/4 wave lines must be dampened, especially at the lengths you guys are using, to be effective. How many of these lines actually get the proper dampening?

LOL.... OK, now this poop is really getting thick... How many of you guys have actually built a stuffed 1/4 wave T-line and tuned (impedance curve) it?

A T-line assumes there is no chamber behind the driver, that is why round T-lines behave most predicably. If you have a chamber, and then a hemolitz resonator attached to the chamber, it is a ported box. T-line gets thrown around in car audio all the time. Just about everything described is in fact not though.... Don't get bent over it, it's just the way it is. Call it something else if you want, just don't call it a T-line, because it isn't one....

A T-line is exactly that. It is a line. Not a box, not a chamber, not a port. It is a line.

None of the boxes in this thread are remotely close to a T-line...

Please do your homework before you pass on missinformation like this...

Those amps would be louder with those BTLs than any other 15" subs made by FI, or most companies for that matter...

Let me get this right, you are comparing the output of a pair of L7 12s to a single BTL 12, right? With the same power, right?

T/S parameters are the single most important indicator on 1) how a driver will (should) sound and 2) the required alignment... You can put any sub in a ported box and make it loud, that doesn't make it right.....

You can't really say for sure the resistance. If the load of the radio changes, the voltage dropped across it will change also. So if you figure out the resistance needed to drop to 5V under full load, it will not work when the radio is idling or not pulling as much current, in this case the volatge might be to high. The only time a resistor will work is when the load stays the same resistance (because you are building a voltage divider)... Most audio equipment doesn't work this way. Buy a small DC-DC converter, they make them that plug into the cigarette lighter for around $10-15.