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Post by mazeroth on Oct 24, 2005 21:01:51 GMT -7
Monte Kay is a very knowledgable speaker builder and is one of the guys that gets to test new PE speakers. Check out the new link I just found on his site: www.mfk-projects.com/subwoofer.htmIf what he's saying is true, then needing more woofers for an IB, opposed to a sealed, wouldn't matter. However, that is not the case, which has been proven time and time again by many IB owners. Discuss
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Post by jman on Oct 25, 2005 3:31:33 GMT -7
"Keep this one thought in mind, Infinite Baffle is better than sealed box. Infinite baffle has always been better than sealed box and it will always be better than sealed box. What is a smaller box doing? Moving farther away from infinite baffle!"
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brady
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Post by brady on Oct 25, 2005 5:08:03 GMT -7
Remember IB configuration throws away/vents half the output.
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Post by ThomasW on Oct 25, 2005 11:35:12 GMT -7
Because?
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brady
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Post by brady on Oct 25, 2005 16:22:06 GMT -7
Because the rear wave is separated from the front wave? There is also less cancellation but thats in favor of the IB. I think I may have gone a little over my head here! Please correct my thinking if you will.
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Post by Pete Mazz on Oct 25, 2005 17:07:58 GMT -7
I can't tell you how many times I hear this mistake made....
Good article.
Pete
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Post by ThomasW on Oct 25, 2005 17:39:30 GMT -7
There is no front wave/rear wave cancellation in any sub design other than a dipole. In a ported sub the rear wave augments the output from the driver.
An IB is just a huge sealed box and functions the same as any sealed box.
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ryans
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Post by ryans on Oct 25, 2005 21:00:56 GMT -7
If what he's saying is true, then needing more woofers for an IB, opposed to a sealed, wouldn't matter. However, that is not the case, which has been proven time and time again by many IB owners. He is absolutely right. It takes just as much displacement in a sealed box as in an IB to reach a given sound level at a given frequency. But remember that the typical sealed box is tuned to 30-40Hz. Therefore the cone excursion and frequency response start to roll off before the woofer reaches its limits. In other words, sealed box subs typically forgo a fair amount of extension in exchange for high SPL in the 40-120Hz region. In an IB, the tuning point is much lower - typically near 20Hz. So IB's don't forgo the low end extension and they have to pay for it with massive amounts of cone displacement.
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brady
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Post by brady on Oct 26, 2005 5:05:32 GMT -7
There is no front wave/rear wave cancellation in any sub design other than a dipole. In a ported sub the rear wave augments the output from the driver. An IB is just a huge sealed box and functions the same as any sealed box.[/quote] Now I remember you saying this, got confused in a sea of info. What effect if any does the rear wave have in a small sealed box, or is a sealed box a sealed box?
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Post by jgilvey on Oct 26, 2005 6:50:23 GMT -7
Good article, I've corrected the misconceptions he mentions ("cone control", "power handling") countless times.
"So if all the above is true how do we stop a woofer from bottoming? Well, we stop driving it in such a way as to bottom it! The question is, what is the woofer capable of based on its excursion limits. Once we know this, we can determine what HP filtering can resolve the problem. It could be that this woofer just can not produce 20 Hz at 115 db like you might want it to. That might require several times the excursion limit of the driver depending on what driver you are using. So, if you don't want it to bottom you just can't try to make it do something it can't do. "
Indeed!
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Post by ThomasW on Oct 26, 2005 7:58:15 GMT -7
A sealed box is a sealed box as far as the rear wave/front wave interaction is concerned.
In either design the rear wave has no impact on the output levels. But the lack of rear wave interaction with the box, is one reason an IB sounds better than a small sealed box.
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Post by mazeroth on Oct 28, 2005 15:50:53 GMT -7
With what Monte is saying, an Avalanche 18 in an IB should have just as much output as an Avelanche 18 in a sealed box, but it doesn't. This is what I don't understand. I can understand how an IB is basically playing with little air "compliance?" behind it, so pushing an Ave18 in and out 27mm is much easier to do than if it were in a sealed box. However, if the Ave18 is moving in and out 27mm, shouldn't it "move" just as much air as a sealed box moving the same woofer in and out 27mm, even though the sealed box takes roughly 2-3x more power to do so?
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ryans
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Post by ryans on Oct 28, 2005 18:30:38 GMT -7
With what Monte is saying, an Avalanche 18 in an IB should have just as much output as an Avelanche 18 in a sealed box, but it doesn't. This is what I don't understand. I can understand how an IB is basically playing with little air "compliance?" behind it, so pushing an Ave18 in and out 27mm is much easier to do than if it were in a sealed box. However, if the Ave18 is moving in and out 27mm, shouldn't it "move" just as much air as a sealed box moving the same woofer in and out 27mm, even though the sealed box takes roughly 2-3x more power to do so? We talk a lot about maximum SPL in the very low frequency range, where excursion is king. But remember that there's plenty of bass up in the 40-80Hz region where you aren't likely to bottom out. In other words, you have to consider the whole frequency response. Not just 20Hz. IB frequency response is naturally going to be very different from the average sealed box. But with enough EQ you could make one sound like the other. And then they would have similar max SPL ... though the IB would require less power to get there.
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Post by jgilvey on Oct 28, 2005 20:06:14 GMT -7
It doesn't? Based on...?
Yes...it's all about displacement...hence my question above.
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Post by Pete Mazz on Oct 29, 2005 15:06:43 GMT -7
From the article:
Pete
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