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Author Topic: System tuning and alignment...  (Read 1494 times)

AllenDeneau

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System tuning and alignment...
« on: January 02, 2014, 01:06:04 pm »

By reading my other post on this forum about measurement software you'll know I'm not that well versed in tuning a system as many of you are... I can get a system to sound pretty good but I certainly know there's a ton more I need to know...

You may have also seen my post regarding trying to help our church get their system dialed in and while I understand a lot of what's going on, there's a lot I'm not sure of as well...

Here's one of those things that I'm not sure of BUT I think a bit of system alignment and tunign will help. Maybe, maybe not, hopefully y'all can help me get a better grasp...

Before I begin, I know I really need to bring a pro in for this and I'm working on it but the problem is, getting them to understand and accept it's an investment and most likely the most important one we'll make but the powers that be aren't letting go of the $$$ yet... I'll get there but before I do I want to have a better understanding of what else can be done and how... I like to be prepared..

Here's the situation. Our church is a 1000 seat flat floor room that is approximately 55' deep from the down stage lip to the back wall. Our room is 150' wide with a few angles here and there but for most practical purposes, it's a rectangle..

When the installing company put the system in they did an exploded main system with 8 JBL AM1525's in 2 rows of 4. One row exploded across the down stage lip and then another about 25' off stage. The need for a "delay" or 2nd row of mains in that shallow room seems unnecessary and overkill. I get "why" they did it; to get better coverage and to keep overall volume lower but the "how" is definately not right... There is major comb filtering in every area of the seating area... But that's another discussion for another time...

So our Subs are Peavey SP118's. There are 4 of them spread across the stage front. 2 of them are under the stage on their sides and 7' from the front row of seats. They're about 15' apart. The other 2 are also split apart and approximately 17' from the 2 middle subs, one on either side of the stage. They're sitting vertically and on a solid platform that's about 2' above the room floor, even with stage height. Below is a rough depiction of the sub arrangement:

Sub                                                            Sub
                      Sub               Sub                 

The 2 widest subs are behind a heavey stage curtain wrapping our SL & SR flanks...

Almost directly above the 2 centered subs are 2 of the mains flown with the lowest point @ 23' in the air. They have a ton of angle on them, almost too much, as the front 4' or so of the stage gets more sound from the mains than the monitors do.. I know that needs addressing as well..

Our system is mono with aux fed subs.
We mix on a Roland M400 and send mains & subs signal via the digital snake back to the amp rack.
Each JBL main is powered by a side of a Crown Xti4000 and the subs have 2 subs per side of an Xti4000.
All processing is done locally within each amp, no system controller or DSP other than the amps. Yet another think I'd like to change..
I haven't yet been inside the amps because the installer has me locked out of the front panel controls and I just haven't had the time to get my laptop there and connect to the USB port to look around..

With that said, I am not sure of the pairing of the subs... All amps seem to be running in parallel mode..

OK, there's all that to ask this question...

I know with the sub positioning I'm getting some bad power alleys and even worse nulls in low end coverage. Our mix location is 50' from the down stage lip just off to the house right side of the center aisle. If I can just start to hear or feel the subs I know I'm about 10dB too hot. A walk over to the center aisle confirms that, major low end...

People in the very front rows complain of "booming" and too much low end, and rightfully so, they're right in front of the subs... We have no center fill speakers and remember, the mains are 20+' above the subs so I know there's a timing issue.

I can't fly these subs and for the time being I have to make what I have work so I'm hoping for some help in pointing me in the right direction. I've tried backing down the subs but, then the whole room loses low end and energy. Like I said, I haven't yet gotten into the amps to peek around or adjust anything. I have worked on the eq for all inputs going into the subs as well as the subs. I made slight cuts in the 80Hz area and really rolled off the upper end of the subs to try to make them less noticeable but still no joy...

I even downloaded Meyers MAPP software to play with sub positioning but I can't get anywhere near even coverage regardless of layout. Obviously I'm using a meyer product in the library with similar specs to our subs..

I'm thinking I need some serious delay of the subs to match the arrival time of the flown mains, maybe? I have never had this much trouble getting even coverage and a smooth system to mix with so I feel a little stumped...

Am I on the right track that I need more delay in the subs to get closer arrival times of the mains and subs so it's not just boom boom boom and then the mains hit? If so, do you determine delay vertically the same way you would horizontally? 23' trim height to bottom which gives me closer to 23.5' to horn center (they're inverted to be horns down) and closer to 24'+ to center of main so somewhere around 20.5ms to 22ms of delay using the quick math..

Here's a link to our room layout and some pics if you're interested. http://www.simplicityentertainment.com/church/

Am I thinking of this the right way, anything I'm missing?

Anyone want to give this a shot?

Thanks...
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Allen D.
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Tim McCulloch

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Re: System tuning and alignment...
« Reply #1 on: January 02, 2014, 10:24:19 pm »

Am I thinking of this the right way, anything I'm missing?

Anyone want to give this a shot?

Thanks...

You can optimize for exactly 1 place in a given space.  All other locations are a compromise.

The sub woofer deployment has interesting interactions with itself, and the predictions shown are without walls, so no reflections.  Feel free to try this at home.  The subs are Meyer 750, but what they are doesn't really matter much, it's the physical distances and frequencies we're interested in.  Spacing and front/back distances were approximated from your linked drawing.
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AllenDeneau

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Re: System tuning and alignment...
« Reply #2 on: January 08, 2014, 01:36:48 am »

Hey Tim, thanks for the reply...

Yeah optimising would only be for one spot however, I do feel like it's possible to get a more even coverage of the low end but I can't seem to get it modeled.

I have been doing just as you did and came up with almost identical results. I've tried arranging them in so many different configurations that I can't even keep it all straight.

Any ideas on spacing and position you may want to share?

If I had double the number of sub cabinets I think I could get it to work but that's not in the equation right now.

I think I can really help myself if I can get the subs in the center delayed to at least be in similar time to the mains overhead then they won't be as noticeable since, hopefully, the highs and lows will arrive at the same time for the front rows. They're the ones with the "complaints" of the subs pounding them. Back at the FOH position you get such a different sound it's almost impossible to eq any inputs that go into the subs because it sounds totally different because of the comb filtering.

When delaying for vertical space, do you use the same method as horizontal gaps? Take the height from the sub to the main and multiply by .9 to get a start? It seems there's got to be more to the equation since I ahve to overcome height difference at an angle.

For example the CSL sub is @ 6' from the front of the seart of the first row. The main is almost directly above it with a cabinet bottom height of @ 23' above the floor. Which really puts the horn like 25' or so... Now since the sub is on plane with the people it's easy to measure and compensate but, since the main is 25' above plus 6' back which gives me an approximate distance from horn to seat front of 24.75' Would you then delay back to 26' or so to start off? That's not taking into account standing or sitting height of the listener, would you figure that into the equation?

Now, with a room 150' wide and only 55' deep from stage lip to back wall, would you expect to need a "delay" or rear zone speaker? Seems like it's not necessary and more harm than good since we're not pushing 110dB and our room is not long enough for any delay type of configiration.

My head is spinning trying to get a good grasp on this math so i can present to the bosses what's up, how we can or not correct it with our current gear etc...

Any help you can give would be great.

Thanks.
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Allen D.
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Ivan Beaver

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Re: System tuning and alignment...
« Reply #3 on: January 08, 2014, 08:02:32 am »

I just did a design for a room that is kinda like yours-very wide-kinda low ceiling and not real deep.

The best sub solution was to use 4 subs spread apart-located out into the room.

There are several things to consider.

When doing a model in 2D you do not see what is happening at a vertical distance from the subs.

By locating the subs out into the room you can get much more even coverage-and reduce the energy on stage.

If you  cross the subs over low enough-and have mains that go low enough-the localization to the subs issue is pretty much a non issue.

I have done this a number of times and it works great.  That is the moving the subs out into the room part.

I have not done an actual job with exploded subs located out in the room.  But the model looks good.

HOWEVER the model does not have reflections-so the actual results would be different.  But I feel confident enough to suggest it to the installer.

Everything is a compromise



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AllenDeneau

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Re: System tuning and alignment...
« Reply #4 on: January 08, 2014, 11:21:03 am »

hey thanks Ivan, I'm still trying to get them to entertain upgrading and using our current gear for other porjects but unfortunately the wheels are turning very slowly.

Interesting suggestion about the subs further in the room, it makes sense but I'm not sure how we'd accomplish that since these subs can't be flown, unless we have cages made for them...

I did try that on the Meyer Mapp program and got a smoother response but like you said, it's 2D and no boundaries so who knows what I was really going to get for results.

If our subs were easily accessed and movable I'd simply try to play a bit and move them around to see what I can accomplish, much like I'd do on live gigs of my own. Unfortunately I can't easily access them & move them as they are, and especially with this stupid broken leg...

I'm glad to hear you suggest the x-over point, it means I'm on the right track with at least some of my thinking as I'd been thinking the same thing. They seem to be crossed over at @ 120 or so, as far as I can tell by eq'ing them via the board. Remember I've ben locked out and hadn't "broken" into them yet to really see whats up. soon, very soon.

So our JBL AM mains have a -3dB point at 41Hz and the -10dB point at 41Hz so I should be able to easily lower the x-over point to get more low end throughout the room with the mains and also make the subs x-over point lower to make them a bit more discreet yes?

No to the delay setting, did you read my thought process above regarding the delay of the subs to the mains in a vertical situation like we have? It seems since they're crossed over so high AND arriving at the listeners ears before the mains that's causing the people in front to feel assaulted by the low end, thougths?

I've got the Bob McCarthy book coming and can't wait to dig into it as you all suggested on the other thread. Thanks.

So here's a "general" question for you. JBL makes a decent product and the Am series don't seem to be the slouch of their lineup. With a room the size of ours do you see a need to have to hang 2 rows of 4 speakers, separated by only 20' or so from front to back, to get good coverage? I believe the idea was to have better coverage and therefore even "volume" throughout the room but the way these are interacting with one another it's causing more harm than good.

I know our speakers don't ahve the output or sensitivity that the Danleys you quoted do but, I'm really, really doubting now that we'd need more than 4 or 5 properly deployed across the down stage edge to get pretty decent SPL and coverage with much less harmful interaction between them. Thoughts?

Thanks all.
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Allen D.
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Tim McCulloch

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Re: System tuning and alignment...
« Reply #5 on: January 08, 2014, 12:26:28 pm »

I did try that on the Meyer Mapp program and got a smoother response but like you said, it's 2D and no boundaries so who knows what I was really going to get for results.

You can put architectural boundaries into MAPP.  Click on the Tools tab on the menu bar and select Architectural Tool.  When you do this and run a new prediction you'll notice that the reflections "fill in" some of the holes and make yet others.  Welcome to the realities of physics.  Ask the Big Boss to change those for you and wait for the laughter...

Quote
If our subs were easily accessed and movable I'd simply try to play a bit and move them around to see what I can accomplish, much like I'd do on live gigs of my own. Unfortunately I can't easily access them & move them as they are, and especially with this stupid broken leg...

I'm glad to hear you suggest the x-over point, it means I'm on the right track with at least some of my thinking as I'd been thinking the same thing. They seem to be crossed over at @ 120 or so, as far as I can tell by eq'ing them via the board. Remember I've ben locked out and hadn't "broken" into them yet to really see whats up. soon, very soon.

So our JBL AM mains have a -3dB point at 41Hz and the -10dB point at 41Hz so I should be able to easily lower the x-over point to get more low end throughout the room with the mains and also make the subs x-over point lower to make them a bit more discreet yes?

I didn't see a specific crossover point suggestion in Ivan's post, but....  I've said this before:  don't autmoatically second-guess the designer/installer - find him and ASK how he arrived at a particular setting or installation configuration.  Might not remember, might be "I always do it that way" or perhaps "I used the higher crossover point to minimize the LF interaction between the main speakers."

Quote
No to the delay setting, did you read my thought process above regarding the delay of the subs to the mains in a vertical situation like we have? It seems since they're crossed over so high AND arriving at the listeners ears before the mains that's causing the people in front to feel assaulted by the low end, thougths?

Delaying the subs to the mains?  For what point in the house?  YOU ONLY GET ONE.  Everyone else gets a different flavor of "screwed", perhaps more or less than currently, but the coverage in the acoustic crossover between subs & tops will change... and delaying the subs won't fix the SPL problem for the folks in the front rows.  Crossing them lower will somewhat reduce the source localization... but it still won't reduce the SPL of 40-80Hz.

Quote
I've got the Bob McCarthy book coming and can't wait to dig into it as you all suggested on the other thread. Thanks.

So here's a "general" question for you. JBL makes a decent product and the Am series don't seem to be the slouch of their lineup. With a room the size of ours do you see a need to have to hang 2 rows of 4 speakers, separated by only 20' or so from front to back, to get good coverage? I believe the idea was to have better coverage and therefore even "volume" throughout the room but the way these are interacting with one another it's causing more harm than good.

I know our speakers don't ahve the output or sensitivity that the Danleys you quoted do but, I'm really, really doubting now that we'd need more than 4 or 5 properly deployed across the down stage edge to get pretty decent SPL and coverage with much less harmful interaction between them. Thoughts?

Thanks all.

You'll find Bob's book one to read multiple times.  I continue to learn new things every time I pick it up, or at least get motivated to look at something differently.  Bob's really good at getting us to challenge our old assumptions.

As for the delay ring, I have a thought (and I think I alluded to this before):  in an effort to minimize slap back off of the auditorium's rear wall the designer opted to do a fairly steep down tilt, and lacking trim height, that required the delay ring to cover the last 1/3 (or so) of the audience.

Speaker sensitivity doesn't enter into this part of a design, this is about coverage.  Based on your earlier description of what you hear between the mains and delays I think there needs to be some measurement applied to see if the delay time is appropriate and give a good look at SPL - it is possible the time is off and the delay speakers too loud...  again understanding that *any* alignment done is only valid for ONE SPOT IN THE OVERLAPPING COVERAGE.  All alignments are compromises - that alignment is about making various components or subsystems to place nice together WHERE THE COVERAGE OF THOSE DEVICES OR SUBSYSTEMS OVERLAP.  The fewer places of overlap and the less severe the overlapping (in terms of SPL), the simpler and more effective the alignment can be, and they will create fewer compromised areas of coverage.

I have some final thoughts, and I thank Brad Weber (who will probably chime in here at some point) for them....  What is your role in the decision making process and under or by whose authority are you charged with making any changes to a system that is already installed, running, and presumably has been accepted by the church from the installer?  As I've read this thread the desired goals and outcomes are yours and have not been attributed to the tech team leader, worship leader or pastorate.  Perhaps you've had discussions with the 'higher ups', but if so you've not told us what *they* want fixed, improved or changed.

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AllenDeneau

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Re: System tuning and alignment...
« Reply #6 on: January 08, 2014, 12:56:53 pm »

Thanks Tim, I appreciate it.

I think I saw in MAPP where you could do that but I opted not to since I'm not really sure of the program and how to operate it as of now. I agree, physics isn't a suggestion, they're laws.. We can push against them all we want but they refuse to cave, LOL!

No there hasn't been a crossover point discussed, I'm not sure where it lies, I haven't yet been into the amps to see. I'm not necessarily second guessing the installer I'm more just wondering what and why. I haven't contacted the installer, I think that's a grerat idea.

You are correct that delaying the subs only shifts the "crap" to another point or points. I haven't had the chance to talk with the people who have made the comments themselves, I'm only going on what I've been relayed :( It doesn't seem as though it's necesarily the SPL but more a matter of the localization of the low end. I do think it's because the highs are arriving later that they're really noticing the "boom" and singling it out. I've sat in those rows before and you really do get a very odd experience in sound coverage.

I am anxiously waiting the arrival of the book to learn more about system aligning and tuning. Unfortunately for years I ran from it as I just wanted to mix. Now that I'm older, not sure about wiser though, I have seen how yo can't really do one  well without understanding the other...

In regards to the "delay ring" I agree with you. I think it was done for the right reasons, just not executed correctly. Unfortunately, as by my other posts, I don't have any real way of measuring the system and interpreting it other than my RTA which isn't the right tool for the job. I do know that when I sit within the triangle of 3 different speakers I can localize and hear all 3 independantly. That makes for a very poor listening experience and even harder to mix for.. I'm in agreement with you that I don't the input and output levels have been set correctly nor has the delay or we wouldn't have all these issues correct?

OK, fair question. My role hasn't been "titled" but I and another person are leading the sound team under the management of the worship leaders. Our worship leader heads all worship and tech and our second worship leader is essentially over the sound team.  When I came on board they asked me what I can do to help fix some of the issues they've noticed. So we as a team have discussed what we feel isn't right, what we want and they've asked me to help get us fixed and pointing to our goal. Our senior leadership hasn't yet been involved yet but will soon. So yes these goals are mine but also of the worship team and leader.

Believe me when I say I'm not trying to renegade this system and change it to how "I want it" but we're working as a team to correct it for the best of the team and the church. Regarding the acceptance of the designed system, I have been told by my leader that it was more of a friend of a guy at church and, as always, comprises were made to get to budget vs get it right. We've grown quite a bit since then and now those comprimises are becoming glaringly obvious.

Ultimately I'm looking to gain more knowledge of how to do things within system alignment and tuning to help our situation as best I can until I can get the funds allocated to bring a pro in and help us. This is unfortunately above my skill level. I understand the tech, I just don't have the practical knowledge to measure it or correct it as it should be. Does that make sense?

Thanks Tim... I appreciate your patience and input, this has been a great growing exercise.. Keep it coming if you can.
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Ronnie.Reels

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Re: System tuning and alignment...
« Reply #7 on: January 08, 2014, 02:10:31 pm »

Thanks Tim, I appreciate it.

I think I saw in MAPP where you could do that but I opted not to since I'm not really sure of the program and how to operate it as of now. I agree, physics isn't a suggestion, they're laws.. We can push against them all we want but they refuse to cave, LOL!

No there hasn't been a crossover point discussed, I'm not sure where it lies, I haven't yet been into the amps to see. I'm not necessarily second guessing the installer I'm more just wondering what and why. I haven't contacted the installer, I think that's a grerat idea.

You are correct that delaying the subs only shifts the "crap" to another point or points. I haven't had the chance to talk with the people who have made the comments themselves, I'm only going on what I've been relayed :( It doesn't seem as though it's necesarily the SPL but more a matter of the localization of the low end. I do think it's because the highs are arriving later that they're really noticing the "boom" and singling it out. I've sat in those rows before and you really do get a very odd experience in sound coverage.

I am anxiously waiting the arrival of the book to learn more about system aligning and tuning. Unfortunately for years I ran from it as I just wanted to mix. Now that I'm older, not sure about wiser though, I have seen how yo can't really do one  well without understanding the other...

In regards to the "delay ring" I agree with you. I think it was done for the right reasons, just not executed correctly. Unfortunately, as by my other posts, I don't have any real way of measuring the system and interpreting it other than my RTA which isn't the right tool for the job. I do know that when I sit within the triangle of 3 different speakers I can localize and hear all 3 independantly. That makes for a very poor listening experience and even harder to mix for.. I'm in agreement with you that I don't the input and output levels have been set correctly nor has the delay or we wouldn't have all these issues correct?

OK, fair question. My role hasn't been "titled" but I and another person are leading the sound team under the management of the worship leaders. Our worship leader heads all worship and tech and our second worship leader is essentially over the sound team.  When I came on board they asked me what I can do to help fix some of the issues they've noticed. So we as a team have discussed what we feel isn't right, what we want and they've asked me to help get us fixed and pointing to our goal. Our senior leadership hasn't yet been involved yet but will soon. So yes these goals are mine but also of the worship team and leader.

Believe me when I say I'm not trying to renegade this system and change it to how "I want it" but we're working as a team to correct it for the best of the team and the church. Regarding the acceptance of the designed system, I have been told by my leader that it was more of a friend of a guy at church and, as always, comprises were made to get to budget vs get it right. We've grown quite a bit since then and now those comprimises are becoming glaringly obvious.

Ultimately I'm looking to gain more knowledge of how to do things within system alignment and tuning to help our situation as best I can until I can get the funds allocated to bring a pro in and help us. This is unfortunately above my skill level. I understand the tech, I just don't have the practical knowledge to measure it or correct it as it should be. Does that make sense?

Thanks Tim... I appreciate your patience and input, this has been a great growing exercise.. Keep it coming if you can.


Allen....I'd be glad to bring my Smaart out and do a little testing/tweaking.  The couple times I've been to church there I thought it sounded pretty good.  I didn't even think it had subs because I never heard much low end at all.  30 minutes, a little eq and delay and we can have it sounding perfect.   
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AllenDeneau

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Re: System tuning and alignment...
« Reply #8 on: January 14, 2014, 11:41:30 am »

Hey Ronnie, that's an awesome offer thanks. Let me get some things set and we'll do that. I'll text you soon.

Yeah, not much in the low end because of the placement. The front rows are getting killed with low endm so we had to dial it all back :(
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Allen D.
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