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I am wanting to know the effects of ported boxes and the Fs of a sub. Do you want to tune the box below, at, or above the Fs of a sub. I’ve always wanted to know more about how the two relate to each other so any help would be appreciated. I’ve always tuned my boxes from 27-35 and had good luck.
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-1 pioneer AVH-P6500-DVD -1 PBX 6.5 Evolution Components -1 alpine MRP-F450 -2 EU-700's in the doors with the components (reg cab ford ranger) Posts: 321 | From: Ladysmith, VA | Registered: Apr 2004
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from my understanding of the Fs value is the natural frequency that the sub resonates at in free air. So my sugestion would be not to tune your box below the Fs value in turn would prevent any unwanted distortion from your woofer or damage
-------------------- ------------------------ + ------------------------ Team WTF we'll never forget 1993 geo storm: world record A/C Posts: 23 | From: weatherford | Registered: Oct 2003
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well that's kinda my understanding also but i guess i'm looking for a more technical answer you know the type of answer you get when people on here try to prove that their product is better then the other persons. lol i like to learn !
-------------------- I'm a Newb tell me how to win !
-1 pioneer AVH-P6500-DVD -1 PBX 6.5 Evolution Components -1 alpine MRP-F450 -2 EU-700's in the doors with the components (reg cab ford ranger) Posts: 321 | From: Ladysmith, VA | Registered: Apr 2004
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how do you mean more technical answer. what ever sub you have will not reproduce sounds below its FS value. So tuning your box below that will just cause distorsion in the sub below its FS value.
-------------------- ------------------------ + ------------------------ Team WTF we'll never forget 1993 geo storm: world record A/C Posts: 23 | From: weatherford | Registered: Oct 2003
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Of course a sub will produce sounds below its resonance. The resonance (Fs) is simply the point, in free-air, where the subwoofer's impedance curve is at a maximum. This is related to the drivers electromechanical parameters and the environment in which it is driven. The port in the chamber will have an effect on the environment that the sub is driven in, so, it will affect the resonance (that is, point of highest impedance) of the system (sub + box)
The Fs of the woofer is only distantly related to the tuning of the box (that is, where the box should be tuned!) For SQ purposes, the transfer function of the vehicle (the cabin gain profile) is as important or more important than the Fs Ported boxes can give you low frequency extension, which is basically headroom for sound. Sealed boxes typically match up better with your average transfer function to sum flat from a response perspective. For SPL purposes you take basically the same profile into consideration but you're looking to maximize your efficiency in energy transfer from sub to mic, which usually occurs at higher frequencies.
Does winISD provide impedance plots? If so, you can design a box, vary the tuning, and see what it does to your box impedance.
quote:Originally posted by Conner: I am wanting to know the effects of ported boxes and the Fs of a sub. Do you want to tune the box below, at, or above the Fs of a sub. I’ve always wanted to know more about how the two relate to each other so any help would be appreciated. I’ve always tuned my boxes from 27-35 and had good luck.
Win ISD alpha have impedance plot. But it is a little more tricky to input data for own driver(s) than Beta version.
When you checking at impedance and SPL, check also excursion on graph.
It is possible to tune belov Fs, but power handling is much lower than with tuning higher than Fs. You also need stiff speaker suspension to have any result and not damage speaker.
IMO if you can tune box 25-30 in car (with big transfer function gain) it is more than enough to cover low frequencies.
Posts: 1820 | From: Ljubljana, Slovenia | Registered: Jan 2000
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For the reasons Shadowstar mentioned, IB, or sealed generally works better in a car for SQ purposes. You are working to minimize the effect of the transfer function. Which a ported box typically won't do, though I have wanted to experiment for a long time with a super low tuning and some crossover fiddling...
If you are looking to maximize SPL, (correct me if I'm wrong, it's not my forte)you are going to look at what the car peaks at first, then design the box to peak at that same freq. The FS of the sub could contribute to higher numbers in this endeavor, but its not going to be what you base your design on. It could be however affect which sub you want to use for a particular application.
Posts: 2276 | From: East | Registered: Jan 2003
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