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Post by ThomasW on Jul 25, 2006 8:23:58 GMT -7
Again, these things have the exact same dip at 20 hz that my 15's did, and my 15's have an FS of 23.5. I don't know why that is. Maybe my meter? It's the effect of the room placement.
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Post by eeyore on Jul 25, 2006 8:42:25 GMT -7
Osuhog! Are your 15's AE IB15's? I have been looking for four of the 8 ohm version. I wonder if yours and mine are different. Mine are last year's model without the chrome phase plug. Appearance doesn't matter as long as performance is the same. I'm unaware if the specs changed from one year to the next. I assume that you are in Oklahoma. I wonder what shipping is like to the Chicago area.
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Post by Darren on Jul 25, 2006 8:44:47 GMT -7
Hey Eeyore,
I'd assume if you are going to use two different manifolds it wouldn't be a big deal if they had slight differences.
This is mighty convenient for you if it works out!
I'll be shipping your amp this morning!
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Post by osuhog on Jul 25, 2006 9:04:16 GMT -7
Osuhog! Are your 15's AE IB15's?( Sorry eeyore, nope they're not. I guess I haven't really mentioned what I was using. I have four Crossfire BMF1528's. These are high end car audio speakers that have been world record holders in SPL competitions. I have mentioned that I work part time at my local A/V store so I get a substantial discount on many things, including these woofers. They retail at about $400 each and are very comparable to JL Audio W6 or W7 woofers, which we sell also. fs - 23.5 xmax - 14mm one way qts - .69 displacement - 4.4 L These are a high quality woofer and they work very well in IB, but not as good as these 18's. My four 15's are about the same as far as how loud and low they go, but they don't sound as good. Just not as tight, punchy, & chest thumping (qts maybe?). My original IB with two of the Crossfire 15's can't touch these two 18's.
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Post by osuhog on Jul 25, 2006 9:46:08 GMT -7
Okay, here is a side by side comparison of my old 15’s and the 18’s in case anyone is interested. That said, this isn’t a completely accurate test. I have moved my couch about 12 inches further away from the manifold since the testing of the 15’s because of some re-decorating that my wife has done. As you can see, my peak at 36 hz or so changes fairly rapidly as my couch is further away. When I move my mic up 12 inches or so, the peak is still there, even with these 18’s. It’s amazing what even just a little movement can do to your peaks and nulls!
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Post by jackgilvey on Jul 25, 2006 10:20:51 GMT -7
Right...these would fit the former. Higher Xmax is something that raises price, but you can get around it with more drivers.
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Post by ThomasW on Jul 25, 2006 10:23:06 GMT -7
It’s amazing what even just a little movement can do to your peaks and nulls! Correcto-mundo... This is the reason the 'pros' recommend taking a sampling of measurements from thoughout the room. Average those to use for setting any EQ.
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Post by osuhog on Jul 25, 2006 13:07:38 GMT -7
There is something that's puzzling to me. How can these two 18's put out basically the same amount of bass with around 5 total liters of displacement compared to almost 18 liters of displacement from my four 15's? Am I missing something? Could there be a misprint on the Crossfire website regarding their displacement? Over 4.4 L for a 15" sub with 14mm of xmax does seem like a lot.
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Post by Darren on Jul 25, 2006 13:15:58 GMT -7
I think a calculation got messed up somewhere. With 14mm of XMAX they shouldn't be rated at 4.4 liters per driver. For comparison, an RL-P15 with 24mm xmax gives about 3.8 liters. I could be wrong though but the individual paramaters don't seem to add up to me.
I'd guess you should be seeing about 2.3 liters of displacement out of each of those 15" drivers. I'm just estimating, I may have missed something.
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Post by ThomasW on Jul 25, 2006 13:30:42 GMT -7
Could there be a misprint on the Crossfire website regarding their displacement? Over 4.4 L for a 15" sub with 14mm of xmax does seem like a lot. I think that's how much volume (space) the driver displaces when put in a box, it's not the Vd of the driver.
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Post by osuhog on Jul 25, 2006 13:43:35 GMT -7
Ahhh...As in, this is how much volume you need to take into consideration and add per woofer when building your sealed or ported enclosure. If that's the case, it all makes more sense now.
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Post by v1rtu0s1ty on Jul 25, 2006 19:00:29 GMT -7
so no one hasn't tried this drivers yet?
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Post by ThomasW on Jul 25, 2006 19:16:10 GMT -7
so no one hasn't tried this drivers yet? Have you missed the fact that osuhog has posted output plots and his impressions of using a pair of the 18"s in this thread? If so look back a page or so...
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Post by chrisbee on Jul 25, 2006 23:13:27 GMT -7
Okay, here is a side by side comparison of my old 15’s and the 18’s in case anyone is interested. That said, this isn’t a completely accurate test. I have moved my couch about 12 inches further away from the manifold since the testing of the 15’s because of some re-decorating that my wife has done. As you can see, my peak at 36 hz or so changes fairly rapidly as my couch is further away. When I move my mic up 12 inches or so, the peak is still there, even with these 18’s. It’s amazing what even just a little movement can do to your peaks and nulls. Don't forget vertical placement of your meter. I get a 6 db difference for 2" vertical change at the listening position. Placing the SPL meter/mic. on a tripod exactly at you ear height is rather more indicative of your response as actually heard. (Providing you don't slump when the film gets boring)
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Post by iamdeman on Jul 26, 2006 6:25:22 GMT -7
I really wish I would have known about these before buying my RFs. I would have gladly tried 8 of them out in place of the the 8 15s I am using. That's not saying, I'm not happy though
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Post by Darren on Jul 26, 2006 7:04:51 GMT -7
I really wish I would have known about these before buying my RFs. I would have gladly tried 8 of them out in place of the the 8 15s I am using. That's not saying, I'm not happy though Oooohhhh.... eight 18" subwoofers... I'm jealous. One day when I get my addition for a dedicated theater room I'm gonna have to try and beat that
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Post by v1rtu0s1ty on Jul 26, 2006 11:28:27 GMT -7
I really wish I would have known about these before buying my RFs. I would have gladly tried 8 of them out in place of the the 8 15s I am using. That's not saying, I'm not happy though Oooohhhh.... eight 18" subwoofers... I'm jealous. One day when I get my addition for a dedicated theater room I'm gonna have to try and beat that 8 18" Isn't that bad for someone's health?
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Post by Darren on Jul 26, 2006 11:34:36 GMT -7
Only if you are a wussie! I'd love to hear such a setup, I can't imagine how it must FEEL. Mine is insane, 8 18" drivers must be unreal when you push them.
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Post by iamdeman on Jul 26, 2006 11:56:42 GMT -7
Only if you are a wussie! I'd love to hear such a setup, I can't imagine how it must FEEL. Mine is insane, 8 18" drivers must be unreal when you push them. Mine is currently 8X15's, you may have misread my post. If I had known of these, I would have done 8X18's
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Post by Darren on Jul 26, 2006 12:05:15 GMT -7
Only if you are a wussie! I'd love to hear such a setup, I can't imagine how it must FEEL. Mine is insane, 8 18" drivers must be unreal when you push them. Mine is currently 8X15's, you may have misread my post. If I had known of these, I would have done 8X18's Ok, yer still insane ;D I like it.
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