I posted this over at another site and thought that it may be of interest here too.
I decided to compare my pair of SDX 15's in an 8cu ft enclosure to a XXX 18 in my ghetto 10cu ft sealed test box since I already had the 18 in the same room trying to detemine my room gain. Nothing too serious. Just for fun and what not. Thought maybe it'd be of interest.
I've been listening to the SDX's for months now and I don't have any complaints about them. The drivers are built nice and the cone looks great. The enclosure they are in is gorgeous, etc. They sound clean and well controlled with music and they will rock out a big bass fest movie pretty well. I've never heard anything bad out of them with actual material. I usually watch movies at -15 to -8 with them and that's nice and loud. This week I've moved the SDX's out of the way and replaced them with my ugly sealed XXX 18 box.
I tried to listen to a variety of different things from music, to TV, bass movies and everything in between. I didn't do anything when switching them other than roughly calibrating the two to the same level. For strictly music listening they sound pretty comparable. I think the slight edge may go to the SDX's here but I'm going from memory so it's hard to say. The XXX seemed to be a little quieter in the upper bass than the SDX's if that makes sense. It's hard to explain. Not tubby or one notey in the least, just different. Could be due to more cone area and most likely more sensitivity in the upper bass for the 2 15's? Like I said I didn't put too much thought into this. I've watched most of Rush: Live in Rio with both and on the 18 it was great just like on the
SDX's. It did seem like Neil's kick drum and toms were deeper than I remembered though. That's basically how I'd break it down the SDX's seemed more punchy and the XXX more extended and deeper. It'd be a close call and I'm not sure which I favor. I think I'd lean slightly toward the pair of SDX's for purely music.
With movies the big 18 just sounded meaner to me. The SDX 15's are fine like I said, I have no complaints with them at all and they handle loud movies quite well. The 18 just felt more tactile than I remember the 15's being with Monster House (I'd just watched it Saturday with my son) and also with Transformers. I'm going off of memory though so I could be hallucinating. (sidenote: I watched Vampire Hunter D, the japanese anime film, on DVD and there was a retarded amount of bass it seemed to me. It does not have the dynamic range of todays well produced movies, so it's compressed and all of the bass is LOUD. I noted some deep stuff in there too. If you're into that kind of thing maybe check it out.) I give movies to the XXX. It made it seem more like the room was going to collapse from alien weaponry and marauding, giant, house monsters than the SDX's do.
I put the boxes in the same spot as close as possible anyway. The SDX's are arranged vertically in a tall sonotube like deal, both front firing. The XXX is much more of a squat endtable type deal and was lower to the ground and out in the room a bit more.
The SDX's roll off below 35hz-40hz. The XXX extends much deeper and flatter more like 25hz before roll off. I know this from modeling and measurements I've taken of both. I really like both of them. It's just interesting noteing the differences and strengths of each. I've taken some measurements of the XXX and SDX's. Almost forgot the amp is the same Crown CE4000 for both.
Following are some measurements for the FR, THD and max sweep levels. A few things of note. The XXX should have a slight advantage in power from the CE4000 because it a roughly 4.5ohm minimum load and the amp is bridged into it. The SDX's are nominal 4.3ohm loads each. Shouldn't be much though since the power rating from Crown is only a 400w difference between 8ohm 2400w and 4ohm bridged 2800w. The amp runs out of gas before any of the drivers get in serious trouble. Both the SDX's and the XXX could use even more at 30hz and above for peaks. The XXX will handle a bit more power at 20hz and below but it's not going to help anything because it will have greatly increasing distortion. It is working VERY hard at the lowest freq's at the maximum spl's.
The only point where there did seem to be any serious distress from the drivers was with the SDX's at 20hz-25hz. During the THD tests there were some noticeable clacking sounds (driver excursion was high)and I'm not sure whether it was the drivers reaching the end of their rope or heavy amp clipping. I would tend to lean towards clipping but the clip lights weren't even flashing on the amp and I have run both CE4000's so hard that they have protected or shutdown many times trying to determine system limits and never heard a noise like that :scratchhead:. I would think that if that was the sound of the amp clipping I would've encountered it before with a XXX, but I never have. At 16, 12.5 and 10hz I could drive the SDX''s all the way to the onset of amp clipping with no such bad noises other than normal surround noise and distortions encountered during high excursion levels.
The FR's shown below are the maximum level right before either the amp clipped or the drivers sounded heavily distressed during the sweep. The SDX's are the red line and the XXX is the green one. Note the much more extended response of the XXX and the quicker roll off and stronger upper bass of the SDX's.
I decided to compare my pair of SDX 15's in an 8cu ft enclosure to a XXX 18 in my ghetto 10cu ft sealed test box since I already had the 18 in the same room trying to detemine my room gain. Nothing too serious. Just for fun and what not. Thought maybe it'd be of interest.
I've been listening to the SDX's for months now and I don't have any complaints about them. The drivers are built nice and the cone looks great. The enclosure they are in is gorgeous, etc. They sound clean and well controlled with music and they will rock out a big bass fest movie pretty well. I've never heard anything bad out of them with actual material. I usually watch movies at -15 to -8 with them and that's nice and loud. This week I've moved the SDX's out of the way and replaced them with my ugly sealed XXX 18 box.
I tried to listen to a variety of different things from music, to TV, bass movies and everything in between. I didn't do anything when switching them other than roughly calibrating the two to the same level. For strictly music listening they sound pretty comparable. I think the slight edge may go to the SDX's here but I'm going from memory so it's hard to say. The XXX seemed to be a little quieter in the upper bass than the SDX's if that makes sense. It's hard to explain. Not tubby or one notey in the least, just different. Could be due to more cone area and most likely more sensitivity in the upper bass for the 2 15's? Like I said I didn't put too much thought into this. I've watched most of Rush: Live in Rio with both and on the 18 it was great just like on the
SDX's. It did seem like Neil's kick drum and toms were deeper than I remembered though. That's basically how I'd break it down the SDX's seemed more punchy and the XXX more extended and deeper. It'd be a close call and I'm not sure which I favor. I think I'd lean slightly toward the pair of SDX's for purely music.
With movies the big 18 just sounded meaner to me. The SDX 15's are fine like I said, I have no complaints with them at all and they handle loud movies quite well. The 18 just felt more tactile than I remember the 15's being with Monster House (I'd just watched it Saturday with my son) and also with Transformers. I'm going off of memory though so I could be hallucinating. (sidenote: I watched Vampire Hunter D, the japanese anime film, on DVD and there was a retarded amount of bass it seemed to me. It does not have the dynamic range of todays well produced movies, so it's compressed and all of the bass is LOUD. I noted some deep stuff in there too. If you're into that kind of thing maybe check it out.) I give movies to the XXX. It made it seem more like the room was going to collapse from alien weaponry and marauding, giant, house monsters than the SDX's do.
I put the boxes in the same spot as close as possible anyway. The SDX's are arranged vertically in a tall sonotube like deal, both front firing. The XXX is much more of a squat endtable type deal and was lower to the ground and out in the room a bit more.
The SDX's roll off below 35hz-40hz. The XXX extends much deeper and flatter more like 25hz before roll off. I know this from modeling and measurements I've taken of both. I really like both of them. It's just interesting noteing the differences and strengths of each. I've taken some measurements of the XXX and SDX's. Almost forgot the amp is the same Crown CE4000 for both.
Following are some measurements for the FR, THD and max sweep levels. A few things of note. The XXX should have a slight advantage in power from the CE4000 because it a roughly 4.5ohm minimum load and the amp is bridged into it. The SDX's are nominal 4.3ohm loads each. Shouldn't be much though since the power rating from Crown is only a 400w difference between 8ohm 2400w and 4ohm bridged 2800w. The amp runs out of gas before any of the drivers get in serious trouble. Both the SDX's and the XXX could use even more at 30hz and above for peaks. The XXX will handle a bit more power at 20hz and below but it's not going to help anything because it will have greatly increasing distortion. It is working VERY hard at the lowest freq's at the maximum spl's.
The only point where there did seem to be any serious distress from the drivers was with the SDX's at 20hz-25hz. During the THD tests there were some noticeable clacking sounds (driver excursion was high)and I'm not sure whether it was the drivers reaching the end of their rope or heavy amp clipping. I would tend to lean towards clipping but the clip lights weren't even flashing on the amp and I have run both CE4000's so hard that they have protected or shutdown many times trying to determine system limits and never heard a noise like that :scratchhead:. I would think that if that was the sound of the amp clipping I would've encountered it before with a XXX, but I never have. At 16, 12.5 and 10hz I could drive the SDX''s all the way to the onset of amp clipping with no such bad noises other than normal surround noise and distortions encountered during high excursion levels.
The FR's shown below are the maximum level right before either the amp clipped or the drivers sounded heavily distressed during the sweep. The SDX's are the red line and the XXX is the green one. Note the much more extended response of the XXX and the quicker roll off and stronger upper bass of the SDX's.