ok alot of you guys on here know I own two 6.5 inch tangband subwoofers in a abc box. Well long story short I sold the box to a friend with the subs in it. This box hit 128.6db at 51 hz on my 150 db capable digital meter on my buddies splash amp; a cheaper brand and is no longer manufactured anymore. Anyway at that time it was before he did any custom install work to the vehicle with wood panels made into nice slots for his amp to mount and a digital capacitor mounted in the same fashion on the other side wall and then he made a wood panel to cover the floor and level it out and then he covered all in nice blue fabric. This was in a older acura integra with a hatchback window and tha box was mounted firing straight up just like it was before the modifications (it fit right between the shock towers) The only other difference was there was a slight slotted gap beneathe the abc box before the custom install was done and later that was no longer there after the cutomizing. Well here comes the intresting part. he goes to our car club gathering and we meter it at the show with my same meter and he only hits 125.2 db! Now keep in mind the amps set the same, the same volume is played, the same frequency is used on the bass cd, and the battery and capacitor is fine as well and yet he looses 3.4 db. The seats were in the same position and everything as before the custom work was done only thing that changed was the custom work. So the next day I call him up and ask to come over and check things out the day after the show wanting to know why the 3.4 db loss happened; and guess what? His best hit frequency changed from 51 hz before the custom install to 42 hz at 126.2 db after the custom install. Intresting isnt it? It was bad for my friends fortune but a great learning experince for me. Anyone have any ideas why this happened? (I have some idea but i wanna hear your input.)
Ps....we also found out me sitting in the passenger seat raised his spl 1 full db with me in it but the readings I gave you in the story were with me out of the car and him in the drivers seat using the headunit volume)
what was the weather like, i remember zac davis saying something on how the weather can change the vehicles resonate hz, im not sure how but i do remember reading it.
A) Its a dual chambered box with two tuning points. The first chamber is .80 cubic feet net and houses the two 6.5 inch tangbands and is tuned to 32 hz. The second chamber is tuned to 45 hz and is empty at .40 cubic feet with a center port inside the box joining chamber one and chamber two. This is what is called a abc enclosure. My point for this example of my story is that the best hit frequency changed from 51 hz to 42 hz after the changes were made to customize the install and the score dropped 3.4 db just from those changes.
Q)"what was the weather like, i remember zac davis saying something on how the weather can change the vehicles resonate hz, im not sure how but i do remember reading it." I also know that what your refereing to dustin is true about temperature but usually it only changes 1 to 2 hz from temperature extremes not 9 hz like my example showed. I am trying to show proof here that theres more to spl then the subs size and power and even xmax limits. Ill leave it to you all to find the clues I have yet to mention outright.
My guess would be the difference in the resonance frequency of the two different vehicles. If everything else is the same like you said, the vehicle is the only variable.
Q)My guess would be the difference in the resonance frequency of the two different vehicles. If everything else is the same like you said, the vehicle is the only variable.
A) No in this example im giving it was always in the acura integra. It was never in any other vehicle in my story.
The batteries were low on the meter the second time? You were at a higher altitude? It was a El Minyo? The car was facing north as opposed to west misalinging natural harmonic and magnetic waves? A bigfoot was in the back seat?
"The only other difference was there was a slight slotted gap beneathe the abc box before the custom install was done and later that was no longer there after the cutomizing"
-Wouldn't that somehow affect his output. It seems thats the only thing that changed.
Q) "The only other difference was there was a slight slotted gap beneathe the abc box before the custom install was done and later that was no longer there after the cutomizing"
-Wouldn't that somehow affect his output. It seems thats the only thing that changed.
Yes I do think that had a small part in it but I also think the materials used in the install had an effect as well as the change in demensions from the custom work in comparrision to the stock layout demensionally speaking. The fact that the stock layout was matal as opposed to wood that covered up the metal caused absorbsion rather than reflective properties but thats a guess on my part. Simply realizing that some materials cause reflection while others absorb opens the door to my conclusion. Then realizing that sound happends in waves and happens in wavelengths opens the door to the actual best hit frequency of the vehicle changing and thats without considering cancellation which is different than reflection or absorbtion properties I mentioned earlier.
