95Honda

Thanks. Flash from the camera makes the lines look weird. The pictures don't do it justice, it looks bad as hell in person... I'm going to try and finish up everything by this weekend, I'll get some better pictures then... This shit is gonna be loud....

Well, good luck. I know the guys at FI know what they are doing when they design these drivers. Performance is usually pretty well optimized... I am also very skeptical of anyone's personal opinions of driver performance in relation to car audio without proper measurements. And I don't mean a Termlab... Everything sounds great 99% of the time to people...

Back from Line-X. They did a real good job, nice and even. The box is dusty in the pictures, I will get it cleaned up after I finish building all the wiring harnesses for the back and build the short RCA cables... She's all buisness boys...

I would, if I simply want a steeper roll-off at the same point by cascading the filters... I.e, 24db/oct HU + 24db/oct Amp = 48db/oct total, 12db/oct + 18db/oct = 30db/oct total, etc... And there is no reason to use either the HU or Amp in any particular preference as long as they fit your filter criteria...

Your going to have measure the gap and calculate clearance with your proposed WW. Are the stock BTL spiders progressive? If you were aiming SPL, I would stay away from linear spiders in fear of mechanical damage... Also, do you have the baskets yet? New 12 spokes are pretty cheap really...

Loudspeaker Design Cookbook by Vance Dickson If you are looking for more detail on ported enclosures, Bullock on boxes by Robert Bullock. A little more in-depth, but goes in to much greater detail on ported box behavior than Loudspeaker Design Cookbook... In fact, it is pretty much vented only...

^^Yes. Hemolitz resonation requires the volume of the enclosure and vent to be within certain parameters to work right. For instance a 1/2 cubic foot box attached to an 8" sonotube for a port will act more like a transmission line than a port. Conversley, if the port is too small you will get an aperiodic effect. Both of these are bad things..

Good luck, I hope you get this sorted out...

Clipping, Battery Voltage and gain settings have absolutely nothing in the remotest way to do with what happened... Something whacked into something and broke something...

When the coil hits the backplate it gets distorted and will run into al these types of problems. Also, for SPL you want high efficiency and the most flux you can get in the gap. This means a small gap with very tight, unforgiving tolerances. I have shimmed coils with 2 layers of manilla envelope on SPL subs... In other words, clank! Your done... Nature of the beast...

I would set it where you think you are going to burp, but again it is all relative. Whatever you end up doing, just be carefull and use your senses when you start wailing on it. Smell for things getting hot, feel parts of the drivers for excessive heat, listen to signs of driver and/or amplifier stress... Do these things and you should be OK. Rely on only one thing (like setting your gain by voltage) and prepare yourself for damage with that power on those subs... Everyone pretty much runs similar equipment in different enclosures/set-ups. What may be safe for someone in thier perspective application may not be the same for you. As we have beaten to death in this thread there are so many variations in impednace from design to design it is very hard to tell how how much is too much power... Like I said, use your senses...

Just do the conversions and acount for your wood thickness. If you were going to go 15" x 17" x 22" internal you would make the front/back 41.6cm x 56cm, the top/bottom 43cm x 56cm and the ends 41.6cm x 46.6cm... Just do the conversions and account for the 1.8cm MDF thickness. If you are worried about gaps, maybe you should pay to have the box built...

Did they say it was 18mm? Normally it is 19mm ( = to 3/4"). When I lived in Korea and Germany, it was always 19mm... Either way I wouldn't sweat it, your cut errors will more than likely be greater than 1mm... I also would do it in metric as mentioned. Just round up a mm to get an even #... A tad bigger won't hurt anything, it may actually help!

No they have rated the Q at 1500 watts, not 2000. 2000 is more than it was rated for. You still don't even understand how reactance plays a role in things here... Bro, I am not even going to respond to you anymore, you have no clue what is going on... This is like your "8 db more efficent T-Lines" garbage a while back... You spread missinformation and the wrong people listen and screw things up... OP- Set the gain so it doesn't sound bad. Be carefull, you can cook those subs with that amp no matter what you do...

OK, I will give you a scenario you can relate to. Take a FI Q 12. It handles 1500 watts and in dual 2 ohm we wire it up for a 4 ohm load. We use JL audio's tutorial for the 1500 watt amp we just bought. We set the voltage to the proper level for 4 ohms and 1500 watts. Now, that woofer will drop down to roughly 2.8-3 ohms at a minimum of 1 point in it's passband. You will be attempting to give it 2000 watts now, and the amp will almost do that. It will be heavily clipped, but still almost 2KW. All this while you safely set the voltage of your 4 ohm sub according to the safe charts JL provided. And on the flip side, you stay conservative at set the voltage threshold to your lowest measured impedance. You are trying to get all the volume you can for a competition and you wonder why your amp is nowhere near max output at your peak frequency. That is because your peak doesn't correspond to your system impedance minimum... Do you see the error in these tutorials now?

If the amp in your scenario is a 3200 watt amp you set if for a 2 ohm load (80V) you are in trouble when the system impedance dips below 2 ohms. That is the whole point here. And 2 ohm nominal subwoofers will drop below 2 ohms in the pass band at least at one resonance point... The whole thing here is Ohm's law is not up for debate. The merit of setting a gain threshold with no real values is what is up for debate. I say it is meaningless when you have tolerances that well exceed 50%, others do not. That is the debate.

Or you just don't waste any time and leave the DMM for something else. It just doesn't work as advertised and is a waste of time + gives false confidence. Additionally, everyone always touts the importantance of getting every last "unclipped" watt out of the amp on car audio forums. Set it to Re and you'll never see full power 99% of the time... You take a kid and give him a DMM and he will mentally masturbate himself for hours using these tutorials. And it won't do a thing for him.... Your missing the point that system efficiency is the link between system impedance and velocity (moreso displacement)... This is the whole exploitation of resonance... We'll never agree, that is OK.

Ugh... You need to make the correlation between system efficiency at resonance. Velocity drops as system efficiency increases. This is the whole point of exploiting resonance. Look, you still just need to understand one thing... Power changes with the same voltage drive when impedance changes. Ohms law. If you truly understood this, you would understand why adjusting power ouput via voltage reference with unknown impedance is not possible. Knowing this is true, why on earth would you set a gain voltage threshold into an unknown load? It is ridiculous if you think about it... I'm done with this. If you can't figure this out, I can't help...

I will try and help with a picture: Here is a plot from a medium dampened 4th order bandpass with a single 10" driver. Lets assume we are setting voltage threshold at 40V RMS. If we do this and set the gain a the 35Hz we will be running about 85 watts. If we don't change a thing, this same alignment will pull 145 watts at 50Hz because of the lower impedance. This is Ohm's law and the way it works. If you set your gain threshold with a certain voltage you most certainly will run into problems when the impedance drops. Not only due to the increased power to the driver, but do to the fact that almost all amplifiers do not act as perfect (they try and be) constant voltage sources into all rated loads. The rail voltage drops. You don't take this into consideration when setting to one voltage reference.

If you can't make the connection that you cannot derive power using voltage reference with unknown impedance than you don't get Ohm's law. That's it.

In response to O'scope: Sure. But then again, this only works at one frequency... As soon as you change frequency you change impedance and power changes. Then it is pointless...

Bro, I am not saying the same thing as you at all... I sited a reference. I am saying that JL is incorrect. There is no correction for this. Le is not interchangable with Re, completely different. I am not talking about what makes up RMS. I am pointing out the fact that you cannot use a voltage reference for deriving power when impedance is unknown... I'm saying the OP cannot set gain by voltage. That is the answer to his question. If somone tells him you can, they are wrong and will lead him to equipment damage. You either get this or you don't... Done beating the horse on this one...

Stopped into the local Line-X shop today. Thier work looks good and prices haven't increased much in the last few years. Will probably get it sprayed Friday...

Re has nothing to do with inductance, it is the DC resistance of the voicecoil. The Re doesn't change with frequency. "Re This is the DC resistance of the driver measured with an ohm meter and it is often referred to as the ‘DCR’. This measurement will almost always be less than the driver’s nominal impedance. Consumers sometimes get concerned the Re is less than the published impedance and fear that amplifiers will be overloaded. Due to the fact that the inductance of a speaker rises with a rise in frequency, it is unlikely that the amplifier will often see the DC resistance as its load." -Taken from Eminence "Understanding Loudspeaker Data", *Note the distinction between Re and Impedance (as impednace contains the reactive component) Impedance is the measurement of resistance that changes with frequency due to the reactance of the voicecoil. If you set anything by voltage level for power output and neglect a change in impedance you are making an error. This isn't my opinion, it's Ohm's law.

Look, I am not making this stuff up. Model any alignment you have built and look at the impedance. You will never (99.9% of the time) see less than at least 50% variation over the bandwith you operate in, much moreso in a vented alignment. It is just the way things are. How would I advise him to set the gain? No matter what he does he has enough power on tap to thermally cook those drivers. So no matter how he sets it he will have the ability to change something in the signal chain somewhere and get more power out of his amplifier than he expects. In other words, there is no bullet proof way to set the gain threshold on an amplifier that doesn't have some type of limiting circuit. You can arrive a setting that may be accurate, but only if you change nothing from then on, and that is impossible... So no, I nor anyone else, can tell him how to set his gain to get an exact maximum level from the amplifier and have it always remain excatly that way. I just doesn't happen. That is why these tutorials are bogus...