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[Ivan Beaver]

Since the chart was labeled TH118, I thought it was a TH118.

Yeah-that would be a "logical" assumption.

Since there is no model number for the project yet, the "base cabinet" was a TH118-but not a standard one and that is why I labeled it as such (for lack of a better name).

Maybe I should have given it a different name.

But sometimes our "working titles" get a bit weird.

You won't believe what the BC series started out as.  Boarding on "obscene"-but funny.

But I won't post it.

[Merlijn van Veen]

I agree with Gunness's paper about the duality or reciprocity BUT, our ears aren't at floor height. More likely something like 5 feet or more above it.

Flown subwoofers and triangulation dictate that some frequencies are gonna cancel, likely resulting in audible changes throughout the audience.

Stacked subwoofers and triangulation virtually negate the chances of this happening, but now we're killing the people in the front.

Pick your poison.

[Ivan Beaver]

I agree with Gunness's paper about the duality or reciprocity BUT, our ears aren't at floor height. More likely something like 5 feet or more above it.

Flown subwoofers and triangulation dictate that some frequencies are gonna cancel, likely resulting in audible changes throughout the audience.

Stacked subwoofers and triangulation virtually negate the chances of this happening, but now we're killing the people in the front.

Pick your poison.

That is why I always try to fly the subs-depending on the venue.

The coverage is much more even in both level and freq response across the audience area.

However in some cases-people want it to be louder in front.

SO-It depends.

What IS important is that people realize the differences in the choices they make.

And also with the differences between end fire and "cardioid" directional sub setups.

Most people think they are the same thing.

[John L Nobile]

Been following this thread closely as I'm moving my system to another room at the end of the month.  I've had my subs centered under the stage and while I like the coupling, they do tend to be loud in the first 2 rows.
I'm now thinking of flying them in the center. It'll be flown from 20" truss so I'm hoping the weight won't be an issue.
I'll discuss it with my install company.

[Ivan Beaver]

Been following this thread closely as I'm moving my system to another room at the end of the month.  I've had my subs centered under the stage and while I like the coupling, they do tend to be loud in the first 2 rows.
I'm now thinking of flying them in the center. It'll be flown from 20" truss so I'm hoping the weight won't be an issue.
I'll discuss it with my install company.

Just one thing to consider when flying subs.

Either get them close or very far away from the ceiling.

You need to be aware of boundaries and the cancellations they can cause.

[John L Nobile]

Just one thing to consider when flying subs.

Either get them close or very far away from the ceiling.

You need to be aware of boundaries and the cancellations they can cause.

I'm thinking 12 feet from the ceiling. That doesn't sound very far.

[Bill Hornibrook]

But doesn't this test just prove that there is no increase in output at floor level?  I think many of us have noticed a substantial difference in low freq output at normal ear level when placing a speaker on the floor, right? From a practical point of view, the audience rarely listens while lying on the floor. Am I missing something?(probably) 

Yeah I'm with this guy. I can think of a number of rooms throughout the years where taking the subs off a stage and putting them on the floor made a substantial difference in their perceived output. There was one large club in particular (over 500 seats) that after years of an "everything must be on the stage" policy finally allowed subs on the floor. During a soundcheck we took them off the stage and set them directly in front of where they were. There was no repositioning of any kind other than that.

The difference was not subtle. We were so amazed that we moved them back and forth several times... just so we could congratulate ourselves on how much better our subs sounded.

Am I missing something here? Maybe floor cancellation if the subs aren't flown 50 feet in the air?

[Ivan Beaver]

Yeah I'm with this guy. I can think of a number of rooms throughout the years where taking the subs off a stage and putting them on the floor made a substantial difference in their perceived output. There was one large club in particular (over 500 seats) that after years of an "everything must be on the stage" policy finally allowed subs on the floor. During a soundcheck we took them off the stage and set them directly in front of where they were. There was no repositioning of any kind other than that.

The difference was not subtle. We were so amazed that we moved them back and forth several times... just so we could congratulate ourselves on how much better our subs sounded.

Am I missing something here? Maybe floor cancellation if the subs aren't flown 50 feet in the air?

There are a lot of different factors involved in "tests" like this.

For example.  Room modes.  The room modes can often have a greater effect on sub performance than anything.

And the reflections (which are part of room modes) can greatly affect the output at different locations.

Here is a little "room mode demo" that is often VERY eye/ear opening.

Put a tone into your subs.  Say 70Hz.  It does not need to be loud-just a comfortable level.   

Now walk around the room and listen for the loud and quiet spots. Remember a couple of each.

Now change the tone to something that is not a multiple of the 60Hz.  Say 53Hz. 

Walk around the room again.  Notice how the loud and quiet spots have moved around.

Of course a lot of the particular outcome depends on the physical dimensions of the room-are they multiples of each other and so forth.  But you should get the idea of how much room modes can affect different freq in different locations differently.

So by simply putting the subs in a different location-the room  may have been moved.

Also the construction of the stage can make a difference on how well the subs couple to the building.  Maybe it was very diaphragmatic and "absorbing" a lot of the sub energy at one or more freq.

So each circumstance can be different-and the freq of interest can be different.

The "problem" (and the it depends) is that when you have a couple of factors (say room modes and position) it is hard to say what is actually affecting the outcome you are getting.  More than 1 variable.

I will agree that in some cases, putting them on the floor results in greater output.  But it could be because of something other than in the air vs ground.

With my test, there was only 1 variable-since I was outside and pretty far from reflections.

What I was addressing was the "general statement" about half space vs whole space.

And unless you were in a very LARGE room, when the subs were on the stage-there were nowhere near whole space.

So-as usual-it depends.

[Caleb Dueck]

I wonder how much higher than 15' and closer than 100' to mic would change things.  We've done many installs with flown subs, the lowest ones were about 24'. 

Boundary interaction seems to be much more important than ground vs flown.  Other than boundaries, flown and ground subs model essentially the same at distance, as Ivan's test confirmed.  The difference is that the front row isn't flattened. 

For us, we model at say 31Hz and 50Hz, and then take into account the boundary interaction(s) through math and experience. 

[Ivan Beaver]

I wonder how much higher than 15' and closer than 100' to mic would change things.

The whole "point" of the test/post was that MANY people believe that you can "simply add 6dB" to a whole space spec.

And that if the mic is in a half space condition,  you already have the "free 6dB".

If I had seen some sort of level difference (more than shown) and freq specific, then I would agree that further investigation would be needed at higher heights.

But for me to go higher-requires renting a lift-going to a larger area and so forth. THAT would not happen anytime soon.

And Let's say that there is a difference at 100'.  What sort of application would that information be useful in?

I believe specs should provide useful information to help a designer determine if one product is more suitable for an application than another.

Yes we have installs in which the subs are actually close to 200' in the air.  HOWEVER-the audience is still in a half space condition.  Even if in bleachers, the size of the bleachers provide a large enough boundary to put them in half space.

I will do some more measurements by raising the mic to 5.5' (standard ear height) and 15'.  But it may be a little while.  Lots of other things to work on that are more "business" oriented and not so much "curiosity".

Of course-somebody else is welcome to do the tests if they want to and show the results.

[ProSoundWeb Community]