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[John L Nobile]

Got a pair of Danley SBH218's. Room is 74'w x 70'd x 18' h. There's an airwall at 70' so the room sometimes becomes 105' deep.

Stage is 28' x 20' x 3' and is starts 3' from the back wall.

I've tried the subs at each side of the stage and together at 4' off from center stage. They're offset 4' from center because of the stage xframes.

I like them best "center but it's a little loud right in front and I still get nodes/antinodes at different frequencies. FOH has a cancellation at 50 hz. Not sure I can do anything about that except knock down walls. I've looked at different bass array types but I don't think they would apply to only 2 subs.

Flying is not an option. I was thinking of putting them both on one side or sliding them back 12' under the stage and delaying the mains. I'd like to not have a power alley and not overwhelm the people in front.

Anyone have any suggestions on placement or DSP?

[Stu McDoniel]

Got a pair of Danley SBH218's. Room is 74'w x 70'd x 18' h. There's an airwall at 70' so the room sometimes becomes 105' deep.

Stage is 28' x 20' x 3' and is starts 3' from the back wall.

I've tried the subs at each side of the stage and together at 4' off from center stage. They're offset 4' from center because of the stage xframes.

I like them best "center but it's a little loud right in front and I still get nodes/antinodes at different frequencies. FOH has a cancellation at 50 hz. Not sure I can do anything about that except knock down walls. I've looked at different bass array types but I don't think they would apply to only 2 subs.

Flying is not an option. I was thinking of putting them both on one side or sliding them back 12' under the stage and delaying the mains. I'd like to not have a power alley and not overwhelm the people in front.

Anyone have any suggestions on placement or DSP?

What are your mains? What is your xover frequencies?  Are you using a high pass?  You have gone through the system and checked polarity?
Ivan will probably tune in on this thread soon.  There is a HUGE amount of variables here.

[Ivan Beaver]

Got a pair of Danley SBH218's. Room is 74'w x 70'd x 18' h. There's an airwall at 70' so the room sometimes becomes 105' deep.

Stage is 28' x 20' x 3' and is starts 3' from the back wall.

I've tried the subs at each side of the stage and together at 4' off from center stage. They're offset 4' from center because of the stage xframes.

I like them best "center but it's a little loud right in front and I still get nodes/antinodes at different frequencies. FOH has a cancellation at 50 hz. Not sure I can do anything about that except knock down walls. I've looked at different bass array types but I don't think they would apply to only 2 subs.

Flying is not an option. I was thinking of putting them both on one side or sliding them back 12' under the stage and delaying the mains. I'd like to not have a power alley and not overwhelm the people in front.

Anyone have any suggestions on placement or DSP?

In an enclosed space-there is practically nothing you can do about the room modes-which are based on the physical dimensions of the room.

[Bob Faulkner]

Got a pair of Danley SBH218's. Room is 74'w x 70'd x 18' h. There's an airwall at 70' so the room sometimes becomes 105' deep.

Stage is 28' x 20' x 3' and is starts 3' from the back wall.

I've tried the subs at each side of the stage and together at 4' off from center stage. They're offset 4' from center because of the stage xframes.

I like them best "center but it's a little loud right in front and I still get nodes/antinodes at different frequencies. FOH has a cancellation at 50 hz. Not sure I can do anything about that except knock down walls. I've looked at different bass array types but I don't think they would apply to only 2 subs.

Flying is not an option. I was thinking of putting them both on one side or sliding them back 12' under the stage and delaying the mains. I'd like to not have a power alley and not overwhelm the people in front.

Anyone have any suggestions on placement or DSP?

Try placing them in the center (just under the stage), and separate them by about 12' (on center of the subs).  They should couple well; therefore, may result in the need to not run them as loud... anyway, as was mentioned earlier, there's a lot of variables.

[John L Nobile]

What are your mains? What is your xover frequencies?  Are you using a high pass?  You have gone through the system and checked polarity?
Ivan will probably tune in on this thread soon.  There is a HUGE amount of variables here.

Mains are Danley SH96HO's. Polarity is right. You can really hear the difference on these speakers. Xover is 90 hz 24db BW on subs and 110 hz 24 db BW on the 96's. HP at 30 hz. Should probably drop it to 20 or 25.
Just wanted to see if there was a way to get less bass in the first rows.

[John L Nobile]

In an enclosed space-there is practically nothing you can do about the room modes-which are based on the physical dimensions of the room.

I thought so but was hoping I was wrong. It's really tempting to turn 50 hz up.
I was playing with lo sine waves after the show and the bass player came out. The lo end got his attention. So I had him walk the room with me. He had no idea lo end acted that way. He stood in a totally dead spot at 50 Hz and put it at 55 and he was shocked that he heard that frequency.
He said that it was like a science experiment and that's when I realized that very few people know about room nodes.
All this DSP available but you still can't beat physics.

[mark lonow]

I thought so but was hoping I was wrong. It's really tempting to turn 50 hz up.
I was playing with lo sine waves after the show and the bass player came out. The lo end got his attention. So I had him walk the room with me. He had no idea lo end acted that way. He stood in a totally dead spot at 50 Hz and put it at 55 and he was shocked that he heard that frequency.
He said that it was like a science experiment and that's when I realized that very few people know about room nodes.
All this DSP available but you still can't beat physics.

u can compromise  the nul
with  level time and  location

2 sources  is all it takes
listen measure experiment in ur place 
use pink noise  maybe  a sine sweep
think bigger picture not one hz

lower the cross over point
70 hz maybe

or maybe just maybe u bought the rong system for that room and maybe  just maybe a cardioid sub could give u less nulz at foh
or try that end fire array 

have fun fighting the nul

[Ivan Beaver]

I thought so but was hoping I was wrong. It's really tempting to turn 50 hz up.
I was playing with lo sine waves after the show and the bass player came out. The lo end got his attention. So I had him walk the room with me. He had no idea lo end acted that way. He stood in a totally dead spot at 50 Hz and put it at 55 and he was shocked that he heard that frequency.
He said that it was like a science experiment and that's when I realized that very few people know about room nodes.
All this DSP available but you still can't beat physics.

It sounds like your "biggest" problem is basic inverse square law-making the seats in the middle louder.-due to them being closer to the subs.

You could try separating the subs (maybe 30-40').

Yes this will not look as "pretty" in a model-but often works to spread the overall energy around so that some seats are not hotter than others.


Also try placing the sub up against the walls (if possible)

This will reduce the reflections that could be part of the null.

Of course in many cases all you do is "shift the problem around", so it is a matter of compromise.

[John L Nobile]

It sounds like your "biggest" problem is basic inverse square law-making the seats in the middle louder.-due to them being closer to the subs.

You could try separating the subs (maybe 30-40').

Yes this will not look as "pretty" in a model-but often works to spread the overall energy around so that some seats are not hotter than others.


Also try placing the sub up against the walls (if possible)

This will reduce the reflections that could be part of the null.

Of course in many cases all you do is "shift the problem around", so it is a matter of compromise.

I've tried modelling different possible  placements and none of them look very good. I've had them 28' apart and they weren't bad there. They do sound best in the middle though. And they seem to couple nicely there. Bass is very consistent throughout the room. As long as you don't walk the room listening to sine waves.
I'm a little surprised that low waves reflect,  sum and cancel like that. I always thought the very low frequencies went through the walls like they weren't even there or the effect was from placing subs on each side of the stage.
Still learning. That's why I'm here lol.

[Ivan Beaver]

I've tried modelling different possible  placements and none of them look very good. I've had them 28' apart and they weren't bad there. They do sound best in the middle though. And they seem to couple nicely there. Bass is very consistent throughout the room. As long as you don't walk the room listening to sine waves.
I'm a little surprised that low waves reflect,  sum and cancel like that. I always thought the very low frequencies went through the walls like they weren't even there or the effect was from placing subs on each side of the stage.
Still learning. That's why I'm here lol.

Do a little experiment.

Take large tub of water and drop a pebble in it.  Watch the wave as they go to the sides and reflect and then cancel and add in certain places.

YEs some energy goes through the walls-but a lot of it gets reflected.  It depends on the wall construction.

The stronger the wall-the more the reflections and the less energy transmitted through it.

It is like a double edged sword.

[ProSoundWeb Community]