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Author Topic: Best option for spaced subs  (Read 2978 times)

Ben Easler

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Best option for spaced subs
« on: November 09, 2017, 07:33:48 am »

Hi all,
I have been reading what seems like countless sub articles and experimenting in the theater I work in. I see that while common, spaced subs are not really idea. However, due to there being a pit cover that sticks out on the raised stage in the theater, placing the subs to the sides of that simply is what makes sense/is possible aesthetically. They were previously hung but this was problematic in the room as well. The overall sound is definitely better with them on the ground but I do have some "power alley" issues as is to be expected. My question is what have you found to be the best compromise? The pit cover is 32' wide so the speaker boxes can be about 35' apart on center at minimum. Right now, I have only delayed the subs to the mains but am thinking I may be able to compromise by delaying one sub to the other. Thoughts or other approaches?
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Tim McCulloch

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Re: Best option for spaced subs
« Reply #1 on: November 09, 2017, 10:42:37 am »

Hi all,
I have been reading what seems like countless sub articles and experimenting in the theater I work in. I see that while common, spaced subs are not really idea. However, due to there being a pit cover that sticks out on the raised stage in the theater, placing the subs to the sides of that simply is what makes sense/is possible aesthetically. They were previously hung but this was problematic in the room as well. The overall sound is definitely better with them on the ground but I do have some "power alley" issues as is to be expected. My question is what have you found to be the best compromise? The pit cover is 32' wide so the speaker boxes can be about 35' apart on center at minimum. Right now, I have only delayed the subs to the mains but am thinking I may be able to compromise by delaying one sub to the other. Thoughts or other approaches?

Delaying one sub relative to the other side only moves "power alley" closer to the side that has been delayed but does not eliminate or moderate the effect.

Your flown subs were probably clustered together, which eliminated power alley but flown, reduced your perceived subwoofer impact.  Flow subs have more even coverage and the advantage of not being right in front of a small portion of the audience.

Why were they moved to the ground?
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Ben Easler

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Re: Best option for spaced subs
« Reply #2 on: November 09, 2017, 03:24:30 pm »

Delaying one sub relative to the other side only moves "power alley" closer to the side that has been delayed but does not eliminate or moderate the effect.

Your flown subs were probably clustered together, which eliminated power alley but flown, reduced your perceived subwoofer impact.  Flow subs have more even coverage and the advantage of not being right in front of a small portion of the audience.

Why were they moved to the ground?

Tim,
Thanks for the response -
The subs were moved to the ground as a few consultants I had come into the space felt that they were not reaching their potential flown. Having read up on this a bit more now, perhaps flown and clustered with some better dsp control would have been a good option. However, for better or worse, they were brought down to have a larger impact and also to create separation between the mains and subs. The theater itself is a quite lively space and tended to create muddiness on the low end. The stage itself also tended to create a lot of bass build up. Perhaps the advice to go in this manner is not the best option but all seem to feel the system does sound better this way. However, I do see that there are low end issues. I know that this is not an uncommon issues. So assuming we cannot or are not flying the subs in the near future and going to try this method, how would you approach it? Would you simply run only one sub? I actually tried this and noticed that the room modes actually created similar areas of less response. In the context of music this is not nearly as big of a deal as with a simple sine wave. Taking measurements, they are not as dissimilar as I would expect either.
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Lee Buckalew

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Re: Best option for spaced subs
« Reply #3 on: November 09, 2017, 03:42:33 pm »

Tim,
However, for better or worse, they were brought down to have a larger impact and also to create separation between the mains and subs. The theater itself is a quite lively space and tended to create muddiness on the low end.

By larger impact do you mean louder or do you mean a better transient response (attacks are "punchier")?
The same muddiness if you have only one sub on?


The stage itself also tended to create a lot of bass build up.

Create bass buildup or be a part of the power alley thus having a significant amount of bass directly form the speakers?


Perhaps the advice to go in this manner is not the best option but all seem to feel the system does sound better this way. However, I do see that there are low end issues.

Go in which manner?
Which layout provided the perceived better sound quality?


Additionally;
What are these subs (make and model)?

Do you have plenty of SPL and enough headroom if there is only one in use?

Do you have the amplification and DSP to separately power and tune the boxes?  I assume so since you indicated possibly trying to time delay 1 sub relative to the other but I wanted to ask.


Lee
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John Chiara

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Re: Best option for spaced subs
« Reply #4 on: November 09, 2017, 04:43:10 pm »

Tim,
Thanks for the response -
The subs were moved to the ground as a few consultants I had come into the space felt that they were not reaching their potential flown. Having read up on this a bit more now, perhaps flown and clustered with some better dsp control would have been a good option. However, for better or worse, they were brought down to have a larger impact and also to create separation between the mains and subs. The theater itself is a quite lively space and tended to create muddiness on the low end. The stage itself also tended to create a lot of bass build up. Perhaps the advice to go in this manner is not the best option but all seem to feel the system does sound better this way. However, I do see that there are low end issues. I know that this is not an uncommon issues. So assuming we cannot or are not flying the subs in the near future and going to try this method, how would you approach it? Would you simply run only one sub? I actually tried this and noticed that the room modes actually created similar areas of less response. In the context of music this is not nearly as big of a deal as with a simple sine wave. Taking measurements, they are not as dissimilar as I would expect either.

'Lively' doesn't cause bass buildup...cubic volume does. And a variety of wall placements.
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Lee Buckalew

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Re: Best option for spaced subs
« Reply #5 on: November 09, 2017, 04:58:52 pm »

'Lively' doesn't cause bass buildup...cubic volume does. And a variety of wall placements.

As does a stage centered between spaced subs  ;)

Lee
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Ben Easler

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Re: Best option for spaced subs
« Reply #6 on: November 09, 2017, 05:15:47 pm »

By larger impact do you mean louder or do you mean a better transient response (attacks are "punchier")?
The same muddiness if you have only one sub on?


I would say both louder and better transient response - I should mention that in this old setup, everything was going through an old BSS soundweb and we didn't have a computer with appropriate ports that we could go in and edit anything. Now, everything goes through a Biamp Audiaflex and I have total control over the DSP.

Create bass buildup or be a part of the power alley thus having a significant amount of bass directly form the speakers?

I'm not sure what you are asking here.. in the context of music, I find the bass to be rather well balanced. I have found with about 3.2 ms of delay between the subs that it is a nice full response across most of the room.

Go in which manner?
Which layout provided the perceived better sound quality?


When they were moved to the floor, everyone who heard the room felt it was an improvement.

Additionally;
What are these subs (make and model)?

They are Renkus Heinz DRS18-2B

Do you have plenty of SPL and enough headroom if there is only one in use?

Yes I believe so..there is definitely more of a transient hit with both but one is not bad either.

Do you have the amplification and DSP to separately power and tune the boxes?  I assume so since you indicated possibly trying to time delay 1 sub relative to the other but I wanted to ask.

Yes we do -  We have a Crown CTS2000 powering these - I wondered if this was underpowered but there is definitely enough volume to more than overpower the room if I would crank the trim on the amps. It is about half up to balance with the system and get a good gain structure.



« Last Edit: November 09, 2017, 05:55:10 pm by Ben Easler »
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Tim Padrick

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Re: Best option for spaced subs
« Reply #7 on: March 08, 2018, 08:06:04 pm »

When they were flown, how far from the ceiling were they?  If they were more than 2' but less than 8', that was the problem - a notch in the frequency response caused by boundary cancellation (for example if they were 4' down, there would be a notch at about 70Hz).
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Ivan Beaver

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Re: Best option for spaced subs
« Reply #8 on: March 08, 2018, 08:21:40 pm »

However, for better or worse, they were brought down to have a larger impact and also to create separation between the mains and subs.
That's strange.  Most people want to ELIMINATE the separation between subs and mains.  To have the sound seem more as one, not different signals.

Yes, they will have more "impact" when on the ground, simply because they are closer to the closest people.

When flown, the coverage is much more even, which is usually important in a theater.  Having the same sound everywhere (or as close as possible)
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Ben Easler

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Re: Best option for spaced subs
« Reply #9 on: May 22, 2018, 01:02:57 pm »

When they were flown, how far from the ceiling were they?  If they were more than 2' but less than 8', that was the problem - a notch in the frequency response caused by boundary cancellation (for example if they were 4' down, there would be a notch at about 70Hz).
This is very possible. There are acoustic panels on the ceiling rather than a true ceiling and they could have very well been in that area. There was not a lot of bass but there was also a lack of clarity. They were also not aux fed in their previous location so the results are more manageable right now even if not great still. The whole system is not flown correctly at the mains. The mains are Renkus STX4/44 and the angle is not downward anywhere close to enough on any of the 3 main clusters so there is definitely some compromise. A line array vs a horizontal array like these would probably do better in general but as far as how we are set up, the sound is definitely workable as it is and produces results that are good but it takes more work than it should.
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