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15" vs 18" subwoofer - which to buy?

If price and room space/aesthetics were not a big issue, is there any reason to get a 15" subwoofer over an 18" one? My main issue is not disturbing the neighbors too much. I'm confused about the difference between a 15" and 18" subwoofer. I want to get the best sound quality possible for low-to-medium volume use.

I've heard that an 18" subwoofer can be played at low decibels and provide good bass resolution and fullness of sound, while to achieve the same volume with a 15" subwoofer, the power has to be much higher. So for any given sound volume, the main difference is in distortion- and higher distortion sound may be more obtrusive. Is this true? it seems counterintuitive that an 18" subwoofer could be better for neighbors than a 15" subwoofer.

However, I compared a B&W800 (12") vs B&W850 (15"). I listened from the other side of the store wall (not as thick as my apt), and at minimum levels which I found satisfying for HT, I found the 12" more obvious and 'boomy' sounding while the 18" produced a more subtle (though actually more powerful), lower frequency vibration, like a very low-level rumbling background earthquake. The 15" subwoofer did seem more of a disturbance because of it's 'obvious' sound. However, I worry that an 18" won't even start producing quality sound until a certain volume that was much higher than a 15", and consequently potentially more disruptive for neighbors. Is this true? What is the relationship between subwoofer size, low sound volume, and subjective listening experience?

Unfortunately, it will be difficult to get an opportunity to hear both the DD-15 and DD-18 which I am considering, so I hope someone can help out here.
no_slouch

Showing 4 responses by cytocycle

cytocycle
1,043 posts
 
If you go BagEnd you need to buy the 18" the 15" wasn't rated a very good value compare to the minimal extra cost of the 18". But the acoustical shaping that the DD's provide will definitely outclass the uncorrected BagEnd. You will need to use a Berinhger or Audio Control Richter Scale or other EQ to correct for the room accoustics and placement to truely compete with the DD's.

if you want your neighbors to have a chance float your sub with a decoupler like the Aurio Pro's (that's what I use on my Velodyne 18") and then mass load the top of the sub with 25lb back of #6 lead shot to tighten the response.

I am also considering the Velodyne DD15 and DD18 since I have an older F1800X without correction (which I will keep to use with the DD15). In my research I am going to go for the DD15 because the only thing different is the size of the enclosure and driver, and I don't need more max output. The other option is to do a pair of bagend 18" (commericial)with a Crown K2 amp and a Tact or Berinhger digital correction system, but I haven't been able to figure out whether I can actually hide 2 18" enclosures behind my couch.
cytocycle
1,043 posts
 
I loved that Audio Control Richter Scale and the sweep it can do I use to use it to shake apartment rooms like 4-8 apartments away and no one could tell where the shaking was coming from.. College was great fun!
cytocycle
1,043 posts
 
Just so you Know I run a Velodyne F1800X behind my couch in a HT setup and now I don't need bass shakers in the couch because it moves the couch plus it doesn't have to be quite as loud, you must crossover at 80hz or below becuase it is in the back of the room. So under my screen is now uncluttered! For movies go for the single 18", if it was music dual small subs but the Electronics will take care of the room problems.
cytocycle
1,043 posts
 
Porschecab: I have to agree that two subs do sound better than one if you can afford it and can place them. Two subs smooth the room response, that is why big line array speakers also provide the same benifit.
Otherwise your suggestion about one properly calibarted (aka Velodyne or other mic/eq sub) makes the most sense. But for Home Theater I would love to have two DD18's but my 2 channel takes priority and buying another Wilson Watch Dog is out of my budget right now.

Chris
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