Ivan Beaver Messages: 9010 Registered: January 2005 Location: Atlanta Ga area
Has No Life
I went to Evans All Time Low show (opening for Fall out boy), last night. I heard the most amazing display of bass and lack thereof in my life!
First the basics. The arena is your typical 13,000 seat arena. It was sectioned off (curtains) so about half-2/3rds of it was being used. Not sure of how many people were there, but there were over 5K in presales-so lets say 6-7K maybe.
The PA was provided by Clair and consisted of 16 I3’s per side and 12BT218’s center clustered in the middle. Power by Lab Gruppen.
FOH was directly in front of the stage at the rear of the floor.
In the general “middle” of the floor the bass was intense and pounding very good. There was a narrow section (about 20’ wide) in the middle (where FOH was) that the bass was really punchy, but as you moved off to the sides (at the rear of the floor) it lost a bit of the punch and just got muddy-but still very strong.
OK here is where it gets weird. I did a good bit of walking around. They only allow 500 people on the floor-so it is easy to move around. As I went forward to the front of the audience –on the sides- and directly under the PA hang-the bass was GONE!!! Not lower-but GONE. I mean at least 20-30dB down (from the center rearof the floor-despite bing only about 15-20' away from the subs). It was the same on both sides. I have NEVER in my life heard that much rejection.
As I walked up the rakes on either side, the bass was just as bad. It just simply was not there. Only the lows from the main PA.
As I walked up behind FOH, it got lower (but nothing as low in level as the sides) and as I got up a little bit in the seating (say halfway) it was pretty much gone.
Evan said they were not doing anything with the bass (steering wise) and the cabinets were all run with the same signal. The cabinets were forming a sideways line array of sorts (being side by side in a row).
Basically the good sub energy was staying on the center part of the main floor (where most of the people were not)
Before anybody thinks otherwise, this is not a knock on the subs themselves, but rather an issue of the physical layout and or room interactions-and maybe something unknown.
So lets say there were 6-7K people there. With only 500 allowed on the floor. And a good number of them off to the sides down front, only maybe 300 were getting good pounding bass. Add a couple hundred more for those seated at the back of the room (most of the people in the stands were to the sides).
Now you have maybe 10% or more, of the people getting the good bass experience.
As with many discussions on sound quality at concerts here, in this case it REALLY depended where you were located. Some would talk about the pounding bass that rattled their bodies, and others would say that there was no bass at all. And they would BOTH be correct. HOw could something that drastic happen at the same concert? Well believe me-IT DID!
Sorry to rant, but I have never in my life, in all the thousands of gigs I have done, and close to a thousand installs-not to mention concerts attended, have I ever heard THAT MUCH variation of the lows/subs etc. It was simply STUNNING!
Evan did say they had been playing with different configurations on the tour. Well THAT ONE, did not work well-for the audience anyway. It was great at FOH-so I guess it really depends on who you are trying to please .
On the rest of the mix, here are a couple of comments. Evan was running the screaming girls (in the audience) WAAAYYY to hot! It was painful. I asked him to turn down the girls and he said he could not.
Being a half empty arena, there was a lot of “room” coming back and overall the sound was very cluttered. This was not due to his mix-which sounded like it would have been fine in a more tame room.
But in situations like this you do not worry about getting a “nice mix” and just concentrate on giving the audience a “Rock-n-roll” experience, and he did that just fine. The band put on a good show and the kids enjoyed it, and that is what it is all about anyway-right?
Regarding the coverage of the rest of the PA, I have no idea. I was so dumbfounded by the bass and how it was reacting, I could not even think about the rest of the system.
But I did miss the floor feeling like it was going to fall in anytime-as the last couple of gigs I have seen ATL.
Nice seeing you again Evan-=keep up the good work and you can go far in this business. We need more people who really care about how it sounds.
Keep on Rockin'
For every complicated question-there is a simple- easy to understand WRONG answer.
Can I have some more talent in the monitors--PLEASE?
Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs
Jon Waller Messages: 235 Registered: April 2004 Location: Michigan
Has No Life
You would think with all the processing built into those amps they could have implemented some delay curvature to that line of subs...
But that would have taken away from the punch felt by the BE's at FOH. And after all, they are the provider's customers, not the 'punters' who are buying the tickets. I actually detest calling the audience that, but it is a term I have heard repeatedly used on this forum.
I know when I am thinking about plunking down money to see a show, the number one thing on my mind is whether or not it is worth the crapshoot of getting enjoyable sound. One of the best sounding, most enjoyable shows I have ever seen was free! (It was Spyro Gyra outdoors a few years ago, sitting right in front of the board).
BTW, what is the driver complement in an I3?Engineer
ISP Technologies
Greg Cameron Messages: 1832 Registered: April 2004 Location: Nevada City, CA
Has No Life
Could be one of those situations where simply going to split sub stacks might have made a big difference in side coverage. Of course, the only way to tell would be to try it. I'm sure time constraints probably forced a decision from the get go though...
Art Welter Messages: 4874 Registered: October 2007 Location: New Mexico
Has No Life
Ivan,
I would not think by itself a 22-24 foot “line” (assuming the cabs were tight packed, not spaced) of lows would be as directional and interact with the mains on the sides and vertically behind and above FOH unless there was significant frequency overlap,
A “J” hang with overlap, and subs time aligned at FOH is my guess for no bass on the rakes on either side, only the lows from the main PA, and the lack of bass halfway up in the seating behind FOH.
This kind of stuff makes me wonder if the set up engineers bothered walking the room, or if they did, what they were listening for.
“Evan did say they had been playing with different configurations on the tour.”
My guess is the set up guys, taking advantage of the low end output of the main hangs and trying to appease the sub hogs, ran the I3s down low.
Do you know if there was an overlap in frequency range between the thirty two I3 cabs and the twelve BT218s?
What would you estimate the distance between the main hangs was?
Evan Kirkendall Messages: 6826 Registered: November 2004 Location: The Internet
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Art, the I3's are a dual 12 design, and they were run down to 80hz last night. The subs kicked in around 80hz as well. The arrays were about 45' apart.
The SE is pretty good and gets the rig sounding good every night, but I guess there was nothing else he could do.
Gabe Nahshon Messages: 439 Registered: January 2005 Location: San Francisco, CA
Has No Life
As someone who has used similarly sized center sub arrays I can offer a few observations. When the subs are deployed with the same delay time, the array is extremely beamy. What works (and is constantly praised) in the lounge with a couple boxes simply doesn't work with a concert sized sub system. Running that long of a line them with no time offset between the sub stacks is simply unacceptable in my opinion. However, when steered using delay or physical offset it is a different story. My best low end experiences have been in when I used the l'acoustics delay arc calculator that is built into the old school array spreadsheet.
Another thing I like to do is put some distance between the sub stacks and run them with no time offset. I've done this with 4 stacks of 3, spaced 10 feet apart. It was pretty even.
I believe bennet had some MAPP models floating around somewhere of a long line of subs with no time offset. Not just ugly, but Fugly.
It looks like a case of too much of a good thing (directivity). Delay tapering the subs will help immensely, as Gabe said.
I personally really like the horizontal line array sub setup in old-style theaters or narrow venues, where the array essentially spans the venue width. This makes for very even coverage.
If I had these 12 subs to work with, I would place 4 in the center, and the remaining 4 in a 3/1 cardiod at either end of the stage, angled out towards the audience.
Then set the delay time of the side sub arrays along the coverage seam of the center cluster where it intercepts the audience in the stands.
This PA looks like it could have used some outfill arrays, too, depending on how far the audience extended to the sides.
Another option would be a flown central subwoofer line array...
I should clarify that I like the cardiod solution more than the arced and/or progressive delay approaches because those can cause a large lobe of LF to show up right in the center of the stage.
If you are in a situation where you need defined coverage in a narrow area (such as multiple stages outdoors for a festival) the spaced horizontal array, these horizontal arrays work well to narrow the LF coverage in the horizontal.
SteveKirby Messages: 2106 Registered: October 2007 Location: Santa Cruz
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Christian Tepfer wrote on Fri, 24 April 2009 13:24
Spacing in between the subs eases the beam as well...
+1, not as sophisticated as delays, but very effective. The conventional wisdom (look up the origins of that phrase sometime) is to tight pack center clustered subs in order to achieve coupling and additional output. In reality, at the wavelengths involved, they will still couple without being pressed together tighter than teenagers at the prom.
There have been postings with MAAP plots showing non-delayed subs spaced out across the front of a stage and showing more uniform coverage.
If you don't want to model it, start with the acoustic centers as far apart as you can get them and still get coupling at the top of your bandpass, and then pull the outer box(s) outwards to get the spread of coverage necessary for the room.
Matthew Knischewsky Messages: 326 Registered: August 2005 Location: Kitchener Ont. Canada
Has No Life
As soon as you get a line of subs that approaches full wavelength (50hZ = 22') you will create a line array. In this case you're creating a line of subs that will cancel everywhere in horizontal that is not directly on axis with the subs. Anywhere but directly in front of the subs will be out of the coverage pattern of the subs.
Here a couple quick an' dirty things to try.
Space the sub cabinets so the drivers are 1/4 wavelength apart center to center. At 80 hz thats 3.5', but with the main array going down to 80, you could probably place them about 4'-4.5' apart. This will help widen the coverage pattern in front of the stage without loosing much output, as the subs are still coupled within 1/4 wavelength.
If you have enough DSP, this is what to try next. starting with the center 2 subs at 0ms, apply .5 ms delay to each sub on either side of the center pair. Now add .5 more delay to the next outside pair, (1ms) and so on. until you get to the outsides of the array. you might not even need .5ms per pair to cover the venue, but it's a start. If you don't have enough DSP channels you can physically place the subs in an arc to create delay.
Art Welter Messages: 4874 Registered: October 2007 Location: New Mexico
Has No Life
Evan,
That is quite an arc going on, how many feet down stage of the subs is forward edge of the array?
Have you noticed how much acoustical overlap there is between sub and the 12”s?
I have been reading all the responses, but the lack of LF Ivan mentioned behind and above the front mix does not correlate in my mind with “too much of a good thing (directivity)”.
That is quite an arc going on, how many feet down stage of the subs is forward edge of the array?
Have you noticed how much acoustical overlap there is between sub and the 12”s?
I have been reading all the responses, but the lack of LF Ivan mentioned behind and above the front mix does not correlate in my mind with “too much of a good thing (directivity)”.
Art Welter
Art,
The subwoofers are going to form a virtual dipole by coupling to the floor in the vertical plane. Whenever LF boxes are placed against a solid boundary, its important to remember the boundary causes "virtual boxes" in the floor, creating basically a 2-high subwoofer array.
That is why in cardiod sub setups you reverse the box closest to the boundary, and not farthest away. This insures the canceling boxes are closest to the center of the "virtual array", and that the vertical lobe behavior of the array is also the cardiod pattern you seek.
If the system was setup as shown, and then aligned in the vicinity of FOH, its not surprising that the relative bass amount other places in the arena was low.
Its also possible, but less likely that the slap back from the rear wall of the arena was cancelling some of the forward sub energy at important mix frequencies in the audience.
There is always the possibility of catching an unusual room mode in the acoustic space, but my guess is that this was more a function of the alignment sounding right at FOH, but causing insufficient bass in the rest of the venue due to the directivity of the bass array.
Physics is physics, and this remains the most likley explanation.
PS I don't know any of the system teching details for sure, I really don't want to seem like I am slagging on the CBA guy from my armchair. Just consider it helpful musings.
It looks like a case of too much of a good thing (directivity). Delay tapering the subs will help immensely, as Gabe said.
I personally really like the horizontal line array sub setup in old-style theaters or narrow venues, where the array essentially spans the venue width. This makes for very even coverage.
If I had these 12 subs to work with, I would place 4 in the center, and the remaining 4 in a 3/1 cardiod at either end of the stage, angled out towards the audience.
Then set the delay time of the side sub arrays along the coverage seam of the center cluster where it intercepts the audience in the stands.
This PA looks like it could have used some outfill arrays, too, depending on how far the audience extended to the sides.
Another option would be a flown central subwoofer line array...
I should clarify that I like the cardiod solution more than the arced and/or progressive delay approaches because those can cause a large lobe of LF to show up right in the center of the stage.
If you are in a situation where you need defined coverage in a narrow area (such as multiple stages outdoors for a festival) the spaced horizontal array, these horizontal arrays work well to narrow the LF coverage in the horizontal.
Hi Phil,
Didn't you use to advocate adding a 12dB Butterworth low pass on the the left and right third of a bass sub horizontal line array.
Beside only using the center one third of the cabinets to cover the high bass where the line array would cause extremely narrow dispersion the Butterworth filter added the time delay you were looking for the outer boxes.
Another example this happened to Al Limberg at an outdoor gig.
He laid down four LAB subs accross the front of the stage which was so low that he could not stack them two high.
He was amazed at how narrow the dispersion was using only four boxes at 42" each (14' wide).
Much much narrower then what Evan was looking at. Too Tall
Curtis H. List
Bridgeport, Mich.
I.A.T.S.E. Local # 274 (Gold Card)
Lansing, Mich
Independent Live Sound Engineer (and I'm Tall Too!)
DAVID J. SYRKO Messages: 114 Registered: June 2004 Location: SOUTH OF PITTSBURGH, PA
Has No Life
A number of years ago on the lab sub forum when the labsub was in it's infancy, I posed the question to Mark Seton about setting up a large number of labsubs mainly center clustered. He said group them in 4's. Then cross the center cluster over at 100 HZ. Depending on how many subs you have, you cross the next group at 90 HZ, then the next group at 80 HZ. This lessens the power alley effect of the subs. I asked this question originally on the lab sub forum, then was directed to the Servodrive forum. However, I think all of that is defunct now. I tried a while back to search for something, and didn't get anywhere.
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There was a narrow section (about 20’ wide) in the middle (where FOH was) that the bass was really punchy, but as you moved off to the sides (at the rear of the floor) it lost a bit of the punch and just got muddy-but still very strong.
Not lower-but GONE. I mean at least 20-30dB down (from the center rearof the floor-despite bing only about 15-20' away from the subs). It was the same on both sides. I have NEVER in my life heard that much rejection. 
HOw could something that drastic happen at the same concert? Well believe me-IT DID!
It was painful. I asked him to turn down the girls and he said he could not. 
