Quentin Jarrell

That is fantastic that you have all that knowledge on t/l enclosures. Instead of just saying my facts and figures are wrong use your extensive knowlege to add some helpful information Duke can use to build his enclosure.

Most of my basic knowledge comes from diyaudio.com, quarter-wave.com, loudspeaker cookbook, and a few other sites and books. My db figures are from actually metering different enclosures. And your right about it not being easy for Alan to hit those type of numbers. I totaly agree, he didn't just throw a box in his truck and hit a 180. It took him years to get where he is at. But he has one woofer and Scott had 13 woofers. Going by the normal guidelines in order for Alan to be as loud as Scott his woofer would have to have the same excursion as Scott's 13 woofers. And the normal power rule is out the window because Alan is running around 40,000 watts and Scott had 156,000. So considering that, we would have to assume that there is a way to get extreme amounts of db increase from an enclosure.

I may have missed it but what type of vehicle do you have?

You got a pic of the doll lets do a side by side comparison

what a load of I did not mean it would make your car 10 db louder. Normal ported enclosures are less than 5% efficient. t/l and horn loaded enclosures can be upwards of 75% efficient. The free air response is 8-12 db louder than a ported enclosure. If you don't think it is true take a meter and put it a few feet in front of a ported box. Then take the same woofer and put it in a T/l and measure it. People are getting upwards of 10and 12 Db boosts with bandpass enclosures. So why would this not be capible with an encosure like the t/l. If it is not possible to get that much gain out of an enclosure please explain how Alan Dante hit over 180 with ONE WOOFER and it took Scott Owens 13 woofers to get close to 180. You have all the right to say that it is all bull, but please add a little helpful information with your remarks that will help this guy out with his enclosure.

NO I knew you were joking.

For the moment don't worry about a compression chamber. For the most part any woofer in the car audio market should not need a compression chamber. Unless you are using a 8 inch woofer or a base level woofer you won't need one. The three thing to remember is: throat area: (port area at the sub) should be around 1.5-1.7 to 1 ratio of the subs sd. mouth area: (port area at the end of the port) should be equal to the subs SD port length: should be tuned to the FS of the woofer. And yes most t-lines are so efficient they are normally 8-12 DB louder than a normal ported enclosure.

No not a blow up doll. Here's a pic of my woman

Correct you don't need acompression chamber. It just helps woofer stay "tight" at high excursion by creating back pressure. Calculating the chamber is complicated. There is a lot of Trig and calculus involved. Normally, volume equal to the Qts of the sub is sufficent. But if you have a decent sub it is not needed. What I attempted to explain about the length is: the port is equal the time is takes the desired sound wave to travel to the end of the port (or mounth). Not equal to the hertz itself. So for 35 hertz it would be: 1108 feet/second divided by 35 cycles/second = 31.657 feet And because you will not fit a 31 foot long port in you house, or car for that matter you can divide it by 4 which will make the rear wave 90 degrees in phase with the woofer's front wave. It's not as efficient as a full transmission line but it will result in a lot more output thana regular ported enclosure. I don't know everything about t-lines but I have built at least a hundred of them. And have figured most of it out by trial and error.

Remember this was back in late 2002 early 2003. I was 18, had never seen something like this done so I figured I would do it.

The vehicle was mine . It was my very first fiberglass job. I learned a lot of what not to deo when working with fiberglass. Everything in the interior was fiberglass even the floorboards. The woman is actually a mold of my girlfriend that was made by using medical plaster bandages. The same thing doctors use to make a cast when you an arm. MA audio was supposed to use the car as a demo vehicle and paint it but the deal fell through. However they gave all the product in the car for free and paid for all the install materials. So I gutted it sold all the product and paid the car off. It stills sits at my house gutted. I am just waitting until I figure out what I want to do with it.

You'll be twice as loud as the comp. The 187's cannot be beat for the price. I would highly recomend doing it ported.

I told ya'll, I do some crazy a$$ installs.

For those who have not seen a Death Penlty 21 here is a few pics of a 21, a 12, and a 2 liter pepsi bottle.

I meant as you dropped the sub in to the mounting hole a little slack was caught between the sub and the baffle.

I missunderstood I thought you meant the wiring was stuck between the sub and the baffle.

Was your wiring backwards? Was the wire chaffed from rubbing on the basket? It should have read higher on the meter if the wire was contacting the sub.

You might have the coils out of phase like you stated but how do know how it is hooked up if you don't know how to remove it from the enclosure? If the coils are out of phase the sub should not move much if tested with a battery.

Here's two videos of a DP 21 in 10 cubes tuned to 32 hertz powered by a Hifonics 2000 watt amp. As soon as I can find my software cd for my termlab I will meter it. video of woofer flex Video of 2007 CrewMax Tundra flexing

She's got the ghetto red interior too.

Just a simple trunk install wrapped in carpet. We still have to put in the plexi and do the trunk lid.

This is a side view of a quartewave transmission line enclosure. It has a compression chamber equal to the drivers' dispalcement to help flatten the response curve below the tuning of the enclosure. Normally a compression chamber is only used when the woofer has a weak motor and supension compared to the moving mass of the woofer. The throat is 1.5 the effective piston area of the woofers to get a db boost around the tuning frequency. Most home systems use a ratio of 1.7 to get a flatter curve. The line itself is 1/4 of (the speed of sound divided by the desired tuning frequency). Not 1/4 the wavelength of the desired tuning frequency itself. So if you wanted the box tuned to 35 hertz the line would need to be 8 feet not 8.75 feet. This is done so the rear sound from the sub is time aligned with the sound coming from the front of woofer at the desired tuning frequency. And yes there are many types of hybrid transmission line enclosures because would be nearly impossible to stick a 8 to 10 foot long pipe in most people's living rooms. That is why we have folded designs.

I don't know about anyone else here but I wouldn't want to mess with the dude that is able to steal a 21 in a ported box by himself. LOL here's a pic of a range I did back in 2003

nice .... but there is not much to see ... sorry (your camera sucks ) ... do lower tones or on music The camera does suck. It's a little Kodak with a video function. The track played was a 60 second sweep 40hz to 0hz. I looked around but I couldn't find anything lower than that. LOL