NUCKIN FUTS Posted August 10, 2011 Report Share Posted August 10, 2011 Easiet way to find reso of car is to do compleete build of wall or box then a 10 inch woofer in a 1cu. ft. box then do a sweep then quarter wave ive always went to the mic spot on the dash. has nothing to do with door to door or roof to floor imo. Super charged you guys have my number if you want me to go into further detail give me a call i dont mind helping. Quote Link to comment Share on other sites More sharing options...
bcpballer64 Posted August 10, 2011 Report Share Posted August 10, 2011 Also, with the sealed box, I believe ( someone correct me if I'm wrong ) that you have to make it so it sees the same amount of cabin space as it would in your finished application. So if you're building a wall, you would want to have your sub in a sealed box, with a big giant trim panel around it. I coul e wrong but it makes sense to me because with the larger cabin area it drops the resonant frequency ( maybe it raises it? ) can't remember which. If I may chime in... I know I am still technically a forum "noob" but I do know about 1/4 wave. I am a Radio Frequency Technician in the Air Force and this is one of the many things we have to learn about. Next time I am home I will look for my training books that explain everything, and try to post stuff that is relivent to the car audio world, but for now I will let you know some of the stuff I know that would be somewhat easy to explain. 1/4 wave is actually 1/4 of the waveformat to be examined. When talking about your car radio, your antenna is ~1/4 wavelenth of the radio station frequency your listening to (it is known as a marconni antenna). Its not perfect, because there is more than one station that your radio can tune to. So, they come up with the average frequency of the entire bandwidth, figure out how long one wavelenth of the average frequency is, and divide it by 4. There are also many other types of antennas too, such as half-wave dipoles, full-wave and even 2 wave. All of these propogate differently. When dealing with fractional waves, you have to understand that they are always in refrence to the original format (it sounds weird but I will touch that in a bit). When some thing is 1/4 wave it could be said that it is 90 degrees (1 full wave lenth = 360 degrees). This also relates to your phase. From my understanding the perfect box, is one that has an infinate baffle and infinate volume. This makes the sound waves from the front of the woofer not interact with the sound waves from the back. (they are 180 degrees out of phase(they cancel each other out)) This would allow for the waves off the front to move through space uninterupted. BUT, as we all know this is completely impossible. SO, the sealed box was conceaved. Now, when you start to add a port you kick it up a notch. Tuning the port to 1/4 wavelenth, actually takes the sound wave and slows it by 90 degrees. So at this frequency you have now brought a canceling wave into one that now complements the one from the front of the woofer. Which is why you see better gains, and why you see that "peak" frequency. Now some might argue that it has to do with the speakers resonant frequency, the vehicals frequency..... It does! What I just described was with a theoretical woofer that is perfect in every way. When you put woofers in a car you have so many reflected waves and resonance it is just crazy. This is why you can see differences with seats up, down, forward, back.... everything matters. Now with what was said by people before me, you can find the "perfect" position for everything by finding 1/4 wavelenth of your desired frequency and tune towards it. So, I hope I helped in answering some questions you may or may not have had and I hope it was easy to follow. I know I am not a professional builder, but this information is just stuff I learned about. Hope you get the answers your looking for, and if you need clarification on anything I said, send me a PM and I will try to get you the best answers that I can. To dustin: The bigger volume of area around the box would lower resonant freq. To Loud Burp: Good shit To OP Read what Loud Burp Said lol. Quote "The strongest reason for people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government." -- (Thomas Jefferson) Link to comment Share on other sites More sharing options...
Supercharged DCs Posted August 10, 2011 Author Report Share Posted August 10, 2011 Can't quote you all on mobile, but thanks for that LoudBurp! Easy to follow and very informative. And thanks Murph, that sounds easy enough (I will have to do it when my current wall is gone). And I will definitely give you a call if I have any other questions, and we can possibly talk about this at Siknic (if Im able to make it ) Quote Bassless once again. Can't seem to keep a system for more than a few weeks Saving for a '06 Nissan 350z, look for build around June 2012. Link to comment Share on other sites More sharing options...
Ric Thornton Posted November 11, 2011 Report Share Posted November 11, 2011 (edited) I get asked this all the time... Honestly I'd love to share all my secrets with you... however that is how I make a living. lol I will give a few hints... well... one. probably the biggest hint I can give you. I've only told this to one other person (not saying others may not have figured this out) and that is Ed Hobby from TDH. My number one rule on all of my enclosures is simple and you can check all of them and find this true. if you measure from the "face" of the enclosure to the opposite loading wall (back panel, ceiling, windshield, etc) and measure from the "face" of the enclosure to the inside back wall of the port... they should be the same. (or very very very close) (obviously this doesn't apply to some BP enclosures) Edited November 11, 2011 by PULSE CAR AUDIO Quote Link to comment Share on other sites More sharing options...
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