HHR Ed

Just looked at the new dB Drag Class matrix. You cannot compete in Street tock with an 18" So you will be in Street Max

at finals top Street Stock B scores were in the 147s. With 1 18" you can certainly beat that with the right box.

New classes are still being defined so we will know more in a few days. But it greatly depends on your build. Where is your box located? How many batteries? If your box is in the trunk you could be in Street C. If your box is in the trunk or on the rear seat you could be in Street Max or SS-No Wall. So you have options. But this may change in a week.

in a daily type setup with the same power, you may not tell much of a difference, but the DC Lv4 will be louder on the meter. As long as the enclosure is correct.

I wouldnt wall a CRX. They excel in no wall and street type designs, so its kind of a waste of a good car. They have very little cargo room to make a proper wall, because of the loading effect of the hatch area in a street type system, a wall wouldnt necessarily be as loud as a street type box. So you would be adding weight and building a bigger box for a less loud of a system. The only plus I see is that its rare to see a walled CRX, but if you really want a wall trade in the CRX for a civic hatch.

GO EAGLES ! kickoff in 1 minute. Yay! Philly is jumpin today

Think ya mean Showtime SPL. But I agree with you. especially about carpet on the box. What about the kids just starting out and building their first boxes but they dont know how to carpet yet. Or they dont have access to a meter and want to test a few boxes before they finish their final version.

You'd have to know what organization you want to compete in. Classes are different in each organization. I can tell you what you would be in in dB Drag Racing. But there is also IASCA USACI MECA NSPL and small local comps. Db Drag The box being in the back seat will put you out of street class. So You will be in Street Max. dB Drag also has Bass Race, but there are no build related classes, just run what you brung. If you intend to compete, I suggest going to the various organizations websites and reading up on rules and such and take a look at schedules to see what is in your area.

please tell us some info. what organization? What equipment? What car? How many batteries? Pics will help. What is the build like? box location etc....

you could do that. Or sell 20 of them and use 20 in a wall.

I have just been informed by T3 Audio that they are trying to move 40) TS 10" single 4 ohm coil subs. They want to sell all 40) for $2000. Subs have never been used but were taken out of the box and mounted in the T3 Demo car, just never hooked up. They will ship direct from T3. JD said it was negotiable also. anyone interested e-mail him at [email protected] and let him know that Ed Lester sent you. Or contact me and I will pass you along. link to sub info http://www.t3audio.com/core.mdv/TS.html

I graduated from Mobile Dynamics Toronto in 1998. I loved it

yes exactly, thing of one of those huge air compressors with a 5hp motor, then look at the little tanks with a 1 hp motor. Same concept.

extreme cars like team Riprock are a whole different animal. The tolerances are so tight that any change in humidity or barometric pressure can effect frequency and score. But in daily type cars its negligeable. You are more likely to see a decrease in score due to the effect of temperature on electrical system and equipment than any acoustical change, Just have to keep in mind to change your burp frequency to compensate. my testing chart here says. 80 deg F cabin temp, 73 deg F enclosure temp. = 38hz, 153.4 dB 65 deg F cabin temp. 62 deg F enclosure temp. = 40hz, 153.4 dB 50 deg F cabin temp, 48 deg F enclosure temp. = 42hz. 153.4 dB 40 deg F cabin temp, 40 deg F enclosure temp. - 43hz. 153.4 dB

you gotta think about the energy it takes to drive a cone of a certain mass 4" in each direction. 500w is not enough energy to push any modern cone 4" each way but 5K is. But lets say 500w can with a new type of cone that has a fraction of the mass that the 5K sub has. Now think about the resistance of the air in the enclosure and in the vehicle. It takes alot of energy to compress all that air, so even if 500w can push the cone 4", it wont move 4" cause the force of the air pushing back on the cone will limit travel to the peak of what 500w can do, while the 5K sub can push alot more air mass. Basically, the 5K sub will be louder

BTW, what I just wrote is why I think its so funny that people put box tuning in there sigs and specs. Like 2.5 cubes tuned to 33 hz, lol What if you put in different subs, what if you add power, what if its cold, what if its hot, what if you put your AC on, what if its raining, what if you put the box in a different car? What your box is tuned to isnt really an important spec. Mine is tuned to 20-80hz.

sorry I left for a bit. Here are a few tidbits. Colder air can be more dense but is not always more dense than hot air, humidity and altitude also come into play here. Also, it isnt necessarily easier to get louder in more dense air. 30 deg F air to 80 deg F air will show very minimal differences in density, so any difference in SPL based soley on density is very minute. Also, the more dense the air is, the harder it will be to achieve the same SPL as with a lower density. This is because the air shows more resistance. Basically you have more air molecules to push so more energy is required. Now, we know that sound travels faster through dense materials like solids than it does through lesser dense materials like air. So basically the denser the air, the faster the wave can travel Changing the resonant frequency of the car and the enclosure. Based on that theory we can say that SPL will be lower in more dense colder air, but the change in density is too small. Also, with a higher frequency you can create more energy per time. So lets says 60hz is 60 full waves a second compared to 30hz 30 full waves a second. So it really effects frequency, and some systems are setup to play better at some frequencies than others, so if the temp drop changes your cars frequency, and you box doesnt matches it better than the hot air, then you score may go up. This can be predicted but it is extremely difficult. Now lets talk about box tuning. You can figure what size a box has to be for a given frequency based on the data of the sub. Cone mass, Motor strength, Moving force. Things like that can tell you how the woofer will move and react to a given power and air volume. Now the car. Just think of the car and box together as a big bandpass. So you have 2 chambers. The Larger chamber is more related to the length of the wave, so larger vehicles usually play lower, smaller vehicles usually play higher. If you tune a box to say 35hz, those formulas used to calculate that are based on infinite airspace around the box, and dont take into account a vehicle's internal volume. So when you shrink the infinite airspace down, you raise the tuning frequency of that enclosure. It is true that in most cases it will raise 5-10hz above what the box is tuned at but is hard to calculate exactly because of the various shapes and sizes of different cars. Sorry if I wasnt too clear, I have been drinking.

yeah most only think they do. Now your car and enclosure frequency response will change when air temp, density, and humidity changes. So most people dont change their frequency they play to compensate so they do a lower number. In stormy cold weather I play 42hz, in clear warm weather I play 46 hz, and do the same number

yes, less air volume will take less energy but also at a higher frequency. so if you have an enclosure and want to raise your tuning, you can simply reduce the internal volume. Think of it like this. Your buddys car broke down and he needs a push, so he steers and you get to shoven. Its flat ground and its only a CRX so its pretty easy to move and you can get it up to a pretty fast pace. Now your other buddy broke down too but he has a 1979 Chevy Suburban. How easy will it be to push that and how fast can you push it?

It does have to do with the physical length of a wave. 20hz is 56ft long and you can figure on wave portions. Like half and quarter. Also has to do with the volume of air sitting in the tube or port or whatever it is. and the impedance of the air mass. The more mass, the harder to move so with a given amount of energy, the mass will move slower than having less mass. Get what I am saying?