posted
so tune it exactly at the resonant freq. I have heard many different things now which includes tuning 10 hz below resonant freq and 8 hz below resonant freq.
anyone else able to offer any suggests?
Posts: 7 | From: Midwest, OH | Registered: Jun 2005
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posted
Depends on your vehicle, box locations, how you test, etc. Both can work very well. If you tune the box to the resonant frequency and don't give your self room, you could miss out on the opportunity to maximize all db's. For example, my car has a resonant frequency of 56Hz, but my best notes are 52 or 55 Hz depending upon what I am doing for testing at the moment. If you tune 7-10Hz below your resonant frequency, you have room to move if you need it. And you might be surprised at the additional SPL you could pick up at that level, especially if you have a parametric eq that is more precise.
But, like anything else in SPL, it's what works in your car for your setup, not what the rest of us are doing.
posted
You can certainly tune your enclosure below your vehicles resonant frequency, but you won't maximize SPL that way. And every vehicle will have a different resonant frequency, the only way to be completely accurate is to do the calculation on your vehicle, although general guidelines might be close.
posted
so can someone tell me what resonant frequency is? I'm not sure is that the peak hz for a vehicle? if it isnt, then how does resonant frequency and your peak hz compare?
peace-
-------------------- .................................................................. 2005 Bass Race 139.9 World Finals Champion 2006 Bass Race 149.9 World Finals Champion 2007 Bass Race 149.9 2nd Place Regionals + Nationals 3rd Place Worlds
posted
Here's one way of looking at it: Imagine blowing air accross the mouth of a bottle to make a sound. The less liquid there is in the bottle, the lower pitched your sound will be. Every enclosed (or semi-enclosed) space has a "native" sound, so to speak. Attempting to calculate it by measuring the cabin is essentially pointless as it is nearly impassible to accurately account for displacement of every internal object (including the driver) not to mention the air leaks.
Here's an easy and relatively accurate way of determining your cabin's peak resonance:
First, you need a rough idea of how large the actual subwoofer enclosure that you plan to build is gonna be (externally) and build a temporary test box which is sealed. Take the box some place not affected by any sort of room or cabin gain such as an open field and do a sine sweep to determine the response of the box. Then, do another sine sweep with the box in your car and compare the response graphs. You might actually notice several ripples in the response due to the cabin acoustics but just go with the highest one. Now, the test box does not have to be as large as the final box that you plan to build but if you make them the same size, that will help you determine the resonant frequency more accurately because you're accounting for the displacement that the box introduces into the cabin - the more displacement, the higher the resonant frequency.
posted
you guys don't take into account vehicle gains at all, just because on paper your box is tuned to 50.323423512 hz doesn't mean that when you put it in your car other factors could make it tuned alot higher or alot lower, thats why what your tuning is on paper means nothing
-------------------- Posts: 6879 | From: Russellville AL | Registered: Nov 2002
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posted
but pvc ports have more turbulance, aeroports are a good thing too, but even with that you have waves going UNDER the ports its all about efficiency
-------------------- Posts: 6879 | From: Russellville AL | Registered: Nov 2002
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posted
dbdraggers use winisd? say it ain't so. that bullcrap will just get you more lost. spl is a long never ending process, always has been, always will be. there is nobody that has this down to a science, those winisd users say that they are going to go out and dominate end up quitting after the first show...
you have to put forth the effort in order to get your desired results.
posted
well considering a 4'' pvc port is like 12 sq inches....if you do a standard crx box with 29 x 29 x 14 across the bottom of the box is 27.5 internal you can go 4-5'' on top and get over 125 sq inches of port vs 48 sq inches with 4 4'' ports =)
-------------------- Posts: 6879 | From: Russellville AL | Registered: Nov 2002
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