hello I am installing a subwoofer for a cafe. the room is 30'x20' and it also has 20foot ceiling. I have powerful enough subwoofer but placement is very difficult due to the design of the room. I only have two options right now, option one is to place 10feet above the ground and option 2 is all the way towards the top of 20feet ceiling. I am sure that most subs are not placed in such a way but I can not convince the interior designer to change accordingly. what kind of effect will this height placement will cause? thank you.
Bass from a subwoofer is generally considered to be omni-directional. There should be no problem installing a subwoofer off the ground, I've done so in several installs. The larger problem occurs in the horizontal direction within the room.
Do not place the sub at the center of the room and try to listen to any possible placement before you decide on a final location. Subwoofers tend towards uneven response when they are just stuck in a location that works for the designer's aethestic. There will probably be loud and not so loud seating areas. Some customers will hear far more bass than other while some will possibly hear little to no bass.
This might not be a problem if the volume is at conversational levels. If you find the bass too irregular with your chosen placement, add a second sub in another location opposite the first.
The matching dimensions of 20' are not good. IF you use 1100 ft/sec as the speed of sound, 20' is 55hz, right in the middle of bass response area.
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Your room has plenty of problems built in. In general, avoid the 'half way' point on any dimension for sub placement. IF multiple subs are used, do not place them symmetrically. What are the chances of helping the room produce better bass?