Metal Posted May 24, 2005 Share Posted May 24, 2005 I listen to loud rock on my stereo in a 12'x 12' (x10'high) room. I have a pair of RB-75. I don't watch TV through this system; it's just for listening to loud music. The RSW-15 is heavy and would be a hassle to carry upstairs, move later, etc. I would prefer two RSW-12 instead (or even just one RSW-12 if that's more then sufficent in a room my size). What, besides money, would I sacrifice by choosing two RSW-12 instead of one RSW-15? Thank you. Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted May 24, 2005 Share Posted May 24, 2005 You would sacrifice nothing, the dual 12's will have more output than the single 15 will. Your talking 24" of cone space vs. 15". Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted May 24, 2005 Share Posted May 24, 2005 Welcome to the forum Metal. The 2 12's would give you more output at the sacrifice of a small amount of extension. Using them primarily for music, I'd say that the extension would not be missed. I'd go for it. Quote Link to comment Share on other sites More sharing options...
Born2RockU Posted May 24, 2005 Share Posted May 24, 2005 FRZNINVT : You would sacrifice nothing, the dual 12's will have more output than the single 15 will. Your talking 24" of cone space vs. 15". Do you own a RSW-15?? The RSW-15 has two 15" speakers ..(front and back) ...that's 30" !! Quote Link to comment Share on other sites More sharing options...
Drew in the desert Posted May 24, 2005 Share Posted May 24, 2005 Keep in mind Bron2rocku, that one of the drivers on the RSW15 and RSW12 is a passive radiator. Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted May 24, 2005 Share Posted May 24, 2005 The passive driver does not count (it's not an active driver), in addition as Drew stated the 12's have passive's as well! (12 X 4 = 48) so put that in your pipe and smoke it! Quote Link to comment Share on other sites More sharing options...
Born2RockU Posted May 24, 2005 Share Posted May 24, 2005 ....I am smokin' it now. Actually tastes pretty good...you outta try some of this !!! ~ Rock On ~ Quote Link to comment Share on other sites More sharing options...
Andy W Posted May 24, 2005 Share Posted May 24, 2005 2 x 12" woofers = 226 sq.in. not 24" 1 x 15" woofer = 177 sq.in. But to truly compare the radiating surface you need to know Sd. The above does not take that into account, and I'd quess that they're close to equal. However the power of 2 RSW12 amps is probably more that 1 RSW15. Quote Link to comment Share on other sites More sharing options...
formica Posted May 24, 2005 Share Posted May 24, 2005 Matched with RB-75's i don't think you'd be sacrificing much with a single RSW-12. You can always add a second one eventually... but I'm figuring your mains will run out of steam before the sub, even at loud levels. BTW, andy is correct in posting the two RSW12 has approximately 25% more radiating area compared to the single RSW15. From a recent thread here: RSW-12: 119dB @ 30Hz 1/8 space, 1 meter RSW-15: 121dB @ 30Hz 1/8 space, 1 meter If you buy two RSW12 and place them in the same corner (coupled) you will theoretically end up with 125dB @ 30Hz 1/8 space, 1 meter ... while placing them in different spots you will probably get about 122dB @ 30Hz 1/8 space, 1 meter. (note that these are 1/8spce measurements for comparison and not anechoic) Rob Quote Link to comment Share on other sites More sharing options...
Born2RockU Posted May 24, 2005 Share Posted May 24, 2005 How many watts are each of these subs ( RSW-15 and the RSW-12) ? Quote Link to comment Share on other sites More sharing options...
Colin Posted May 24, 2005 Share Posted May 24, 2005 First, a 12 by 12 room is tiny for such large subs, so either one will do more than a good enough job, but be aware that a small square room will not only have boomy upper bass, it will also have a high null (suck-out), which you may or may not notice with so much bass in such a little room. I forget the formula, but I am guessing the problem area will be somewhere around 100hz. Acoustic panels, corners or walls of books are definitely a good idea in that room. The low frequency on the 12 is 22, only a few cycles per second above the slightly deeper 19Hz of the 15. This is hardly noticeable in a small room. Serious depth is nice for movies and classical music. It is not as important for the mid-bass punch of rock. I dont know the bump on the frequency response of the 12, but two of them will give you double the output yes, but this will be most noticeable at that bump. Say its 40Hz for example, you will be getting double the output at 40hz. You will also get double the wattage: 1250 versus 650 for the RSW-15. Although the 15 weighs 85 lbs, two of the 12s will weigh 116 lbs. Theoretically, you can hear the location of mid and upper bass. Stick the sub behind you and the bass player will sound like he is alone there, while the rest of the band plays along the front wall. Industry giant harmon kardon provides a white paper showing their research proves that dual subs do a better job in a room, not just because they create a better stereo image, but because using them at opposite end of the room does a better job of filling in the nulls. I think either one would be plenty for that room! Quote Link to comment Share on other sites More sharing options...
formica Posted May 24, 2005 Share Posted May 24, 2005 ---------------- On 5/24/2005 12:45:56 PM Colin wrote: I forget the formula, but I am guessing the problem area will be somewhere around 100hz. ---------------- Frequency = (speed of sound)/wavelength If you are looking for the trouble "frequency" in the case of the primary axial mode we have a wavelength equal to twice the room dimension being analysed (distance sound traveled from the woofer to the rearwall and back to the woofer) 12ft = 1130ft/s / 12x2 = 47Hz 12ft = 1130ft/s / 12x2 = 47Hz 10ft = 1130ft/s / 10x2 = 56-1/2Hz Subsequent axial modes will simply be factors of these ... but this is an oversimplification, as there are also tangential and oblique modes as well mixed into the same soup. What Colin is trying to say it that given you have two 12ft dimensions and a close 10ft one... you will end up with a peaky in room response (esp around 47Hz) It's just an unfortunate fact of life... Rob Quote Link to comment Share on other sites More sharing options...
michael hurd Posted May 24, 2005 Share Posted May 24, 2005 So, in this case, I would run the RB-75's as small, and keep the crossover frequency on the sub or subs, very low, say 30 hz or so. By doing this, you would not have a huge bump in the 50 hz region. Quote Link to comment Share on other sites More sharing options...
Blackmesa Posted May 24, 2005 Share Posted May 24, 2005 ---------------- On 5/24/2005 7:28:43 AM Frzninvt wrote: You would sacrifice nothing, the dual 12's will have more output than the single 15 will. Your talking 24" of cone space vs. 15". ---------------- Did someone fail geometry class? also, technically speaking, sub drivers are not even flat so it becomes a 2D curved surface, not just a flat disk (ie PI r ^2), so to get the actually surface area you need to do a surface integral. Good luck with that and i dont really care. bottom line is, I would get two KW-120's. **** the rsw's Quote Link to comment Share on other sites More sharing options...
InnovaZero Posted May 24, 2005 Share Posted May 24, 2005 ---------------- On 5/24/2005 9:09:27 PM Blackmesa wrote: ---------------- On 5/24/2005 7:28:43 AM Frzninvt wrote: You would sacrifice nothing, the dual 12's will have more output than the single 15 will. Your talking 24" of cone space vs. 15". ---------------- bottom line is, I would get two KW-120's. **** the rsw's ---------------- Haha yeah, you get the best of both worlds. 12" woofer with the 15" motor structure, in a better enclosure. Two of these things puts holes in your chest! Quote Link to comment Share on other sites More sharing options...
MrMcGoo Posted May 24, 2005 Share Posted May 24, 2005 The RB-75s fall off below 42 Hz. A crossover on the receiver or processor should be set one full octave above the mains F-3 or 80 Hz in this case. A 30 hz crossover would leave a 10 Hz gap and would not blend well. THX has spent a lot of time and money scietifically testing to come to these conclusions. They seem to work for me. Bill Quote Link to comment Share on other sites More sharing options...
michael hurd Posted May 24, 2005 Share Posted May 24, 2005 Agreed, in most circumstances, but in the case of a small room, where there is significant evidence of a large hump around 40-50 hz, it makes more sense to set the subwoofer crossover to a much lower frequency, thus obtaining a flatter response. Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted May 24, 2005 Share Posted May 24, 2005 Either way 12 by 12 room dimension as mentioned above will most likely present troublesome accoustics. Get the RSW12 and take the extra money saved and think about buying some bass traps, after you measure the room response with what you have. Quote Link to comment Share on other sites More sharing options...
MrMcGoo Posted May 25, 2005 Share Posted May 25, 2005 The RSW-12 falls off fast below 30 Hz. It is better to use traps and/or a notch filter to solve the room problem than to have a gap. Sub placement may also help, if there is some flexibility in locations. Bill Quote Link to comment Share on other sites More sharing options...
Metal Posted May 25, 2005 Author Share Posted May 25, 2005 Thank you everyone for the quick and awesome responses! I'm going to get one RSW-12. Thank you! Quote Link to comment Share on other sites More sharing options...
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