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[Jerry Turnbow]

I'm not sure if this is the right forum, but a quick search on "cardiod subs" didn't give much info regarding my situation.

I have a client in a pre-fab steel building that is getting complaints about LF rattling the houses behind them, several hundred feet away.

Obviously, the best (and most expensive) solution is to build a real wall, with some mass to it, instead of having essentially a huge diaphragm resonating with and passing on all that energy.

Has anyone had any degree of success using cardiod subs in this situation?  All the searching and reading I've done on it turn up mostly outdoor and/or very large venues such as arenas.

The building itself is roughly 150' wide by 80' deep, with the stage in the middle of one of the long walls.

Thanks in advance for any ideas, thoughts, etc!

Note:  Before anyone squawks, I know that "cardiod subs" is one of several methods of deploying identical subs, mechanical seperation, signal inversion, etc., and not some magic "out of the box" solution.

If you have experience with this, I'd be interested in knowing which technique you used for achieving the desired result.

[Lee Buckalew]

I'm not sure if this is the right forum, but a quick search on "cardiod subs" didn't give much info regarding my situation.

I have a client in a pre-fab steel building that is getting complaints about LF rattling the houses behind them, several hundred feet away.

Obviously, the best (and most expensive) solution is to build a real wall, with some mass to it, instead of having essentially a huge diaphragm resonating with and passing on all that energy.

Has anyone had any degree of success using cardiod subs in this situation?  All the searching and reading I've done on it turn up mostly outdoor and/or very large venues such as arenas.

The building itself is roughly 150' wide by 80' deep, with the stage in the middle of one of the long walls.

Thanks in advance for any ideas, thoughts, etc!

Note:  Before anyone squawks, I know that "cardiod subs" is one of several methods of deploying identical subs, mechanical seperation, signal inversion, etc., and not some magic "out of the box" solution.

If you have experience with this, I'd be interested in knowing which technique you used for achieving the desired result.

Jerry,
Earlier this year I was in that building and took SPL measurements inside and out to determine bleed.  I gave the church a list of recommendations that included an approach utilizing both cardioid sub arrays and providing additional acoustical isolation where some is sorely lacking.  The current stage construction is a large limiting factor for utilizing directional sub control as it will need significant reconstruction to allow for proper interaction of the subwoofer's acoustic pressures.

Lee

[Brad Weber]

I have a client in a pre-fab steel building that is getting complaints about LF rattling the houses behind them, several hundred feet away.

Obviously, the best (and most expensive) solution is to build a real wall, with some mass to it, instead of having essentially a huge diaphragm resonating with and passing on all that energy.

Has anyone had any degree of success using cardiod subs in this situation?  All the searching and reading I've done on it turn up mostly outdoor and/or very large venues such as arenas.

The building itself is roughly 150' wide by 80' deep, with the stage in the middle of one of the long walls.

I would think it would depend on what reduction you are trying to achieve at what frequencies and what is practical to achieve.

If they complain about the kick or bass without the system even being on then cardioid subs won't fix the problem.  More practically, can sufficient reduction be achieved over the entire operating range of the subs and while also accounting for the potential contribution of other sources and indirect/reverberant sound?

[Arthur Skudra]

It will be difficult problem to solve.  You really need to test at the houses to figure out exactly what the nature of the problem is.  Is it vibration through the ground, or is it transmitted through the air?  Figure that out first, then you can make intelligent choices on a course of action.  Obviously the client "cheaped out" on the building construction...

[Weogo Reed]

Hi Jerry,

"Note:  Before anyone squawks, I know that "cardiod subs" is one of several methods of deploying identical subs, mechanical seperation, signal inversion, etc., and not some magic "out of the box" solution."

There are subs that are in fact cardoid out of the box, and pretty much over their useful range.
A stack of these might take up less space than several properly spaced 'standard' subs.
D&B, Nexo and others have cardioid subs.

Thanks and good health,  Weogo

[Lee Buckalew]

It will be difficult problem to solve.  You really need to test at the houses to figure out exactly what the nature of the problem is.  Is it vibration through the ground, or is it transmitted through the air?  Figure that out first, then you can make intelligent choices on a course of action.  Obviously the client "cheaped out" on the building construction...

As I noted earlier, many months ago we were asked to come out and give a brief recommendation of how this church could proceed with solving this problem.  At that time, since we had been asked to provide a free site survey to look at how this problem would need to be addressed, simple SPL measurements were taken inside and out in order to determine if there was a significant problem with leakage around building penetrations or if it seemed to be more of a tympanic resonance of the building or a combination of issues. The houses in question are more than 150 yards away from the building.

As a part of my recommendation, the church was told that the next step would be to have us come in and have an analysis performed where full frequency calibrated SPL plots would made inside the building along the back wall, outside the building along the same wall and then at various points moving toward the houses in question including measurement inside the bedrooms, where the complaints originate (the people claim they are being awakened by the bass early in the morning on Sunday).
Only after this analysis could we determine for certain what approach would actually work the best to tame the problem.  The church was given an idea of the cost of analysis and what some possible solutions may cost so that they had an idea for budgeting.  Most likely the solution will be multi-part and will include both bass control(of some type) and structural changes to seal pathways through the wall and to break up resonances of the structure.

It sounds to me as though the church did not like the idea that this was a complex problem and would require a complex solution in order to be a good neighbor.  They have now contacted someone else to get another opinion.  I am more than willing to team up on this Jerry if you do not have the analysis tools.  Perhaps the same opinion coming from two companies would convince the church that the problem is in fact complex and will require an integrated solution of structural treatment and acoustical changes.

Lee

[Ivan Beaver]

As I noted earlier, many months ago we were asked to come out and give a brief recommendation of how this church could proceed with solving this problem.  At that time, since we had been asked to provide a free site survey to look at how this problem would need to be addressed, simple SPL measurements were taken inside and out in order to determine if there was a significant problem with leakage around building penetrations or if it seemed to be more of a tympanic resonance of the building or a combination of issues. The houses in question are more than 150 yards away from the building.

As a part of my recommendation, the church was told that the next step would be to have us come in and have an analysis performed where full frequency calibrated SPL plots would made inside the building along the back wall, outside the building along the same wall and then at various points moving toward the houses in question including measurement inside the bedrooms, where the complaints originate (the people claim they are being awakened by the bass early in the morning on Sunday).
Only after this analysis could we determine for certain what approach would actually work the best to tame the problem.  The church was given an idea of the cost of analysis and what some possible solutions may cost so that they had an idea for budgeting.  Most likely the solution will be multi-part and will include both bass control(of some type) and structural changes to seal pathways through the wall and to break up resonances of the structure.

It sounds to me as though the church did not like the idea that this was a complex problem and would require a complex solution in order to be a good neighbor.  They have now contacted someone else to get another opinion.  I am more than willing to team up on this Jerry if you do not have the analysis tools.  Perhaps the same opinion coming from two companies would convince the church that the problem is in fact complex and will require an integrated solution of structural treatment and acoustical changes.

Lee

It sounds as if you took the "engineering approach" and not the "seat of the pants" approach that the church was looking for.

The problem with the "quick guess" approach is that it may or may not be right.  Mids and highs are one thing, bass is quite another-and takes more "real work" (like you were proposing) to identify the real problems-where they are coming from- and how to attach them.

Cardioid subs can get a great tool-if there are no boundaries.  But put them in a building-and the problem area is outside the building-now all bets are off as to whether or not they will make a difference in the problem area 150yds away.

Of course the REAL problem is that the church did not build a proper building for their uses in the first place.  If they had told the designer the style of worship and a desire not to disturb the neighbors, then the problem would fall into his lap.  Of course that type of construction would have cost a lot more money and they probably would not have paid it.

Just because somebody "desires" a cheap solution' does not mean one is available.

[g'bye, Dick Rees]

Of course the REAL problem is that the church did not build a proper building for their uses in the first place.  If they had told the designer the style of worship and a desire not to disturb the neighbors, then the problem would fall into his lap.  Of course that type of construction would have cost a lot more money and they probably would not have paid it.

Just because somebody "desires" a cheap solution' does not mean one is available.

Ivan.....

This may well be a continuation of a thread on the old Forum.  It would be very coincidental if two such situations were so similar.  The building in that thread was an existing one being adapted for new use.  I doubt that a church would do new construction and make it out of "tin" or steel.......

And it does sound like they're looking for a quick fix for little money rather than actually paying Lee or someone to do the real work required.  If it was me I'd change the measured distance of 150 yards to one of 150 miles and make that as close as I'd get to the situation.

[Lee Buckalew]

Because of the difficulting in predicting directional sub behaviour in this situation and how it would affect the problem I recomended that the church rent in some subs and we would run tests (of course after analyzing the problem more thoroughly).
We'll see how they proceed.

lee

[Jerry Turnbow]

Hi Jerry,

"Note:  Before anyone squawks, I know that "cardiod subs" is one of several methods of deploying identical subs, mechanical seperation, signal inversion, etc., and not some magic "out of the box" solution."

There are subs that are in fact cardoid out of the box, and pretty much over their useful range.
A stack of these might take up less space than several properly spaced 'standard' subs.
D&B, Nexo and others have cardioid subs.

Thanks and good health,  Weogo

Thanks, Weego - I had heard that some folks were already making such things, but didn't know who or to what extent they were in use.

- Jerry

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