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[Eric Lyon]

First let me say I am not anywhere close to a professional in sound. What I am is the person my school system has chosen to find answers to problems with most of our sound needs. This is a fairly long question with a few parts.

This is about stadium sound, our stadium is semi sunken and currently we have 2 - Elements™ 115C 105X60RT with a IPR2™ 5000 DSP for power to the speakers. They are mounted centrally on the pressbox and do a good job to provide sound thru the entire stadium. The first problem is when I have a speaker on the field for example - graduation, it is really hard for them to speak due to the reverb bouncing around the stadium. It takes more than a few seconds for each spoken word to dissipate. Ideas or thoughts about how I can make it easier for the person on the field to speak? I have a podium we could hide a monitor inside. A wireless solution would be best.

Second part of this is about microphones. Its about 250ft from the microphone to the receiver. On a salesman's suggestion we bought a high dollar line 6 mic and receiver. It works decent when the stadium is empty but due to the 2.4ghz it runs on, when I put 1000 cellphones and humans between them the signal is slow and drops out. Other microphones that would be a better solution in this situation?

Let me say thanks in advance.

[Ray Aberle]

Solution one: wireless IEMs.
Solution two: Either directional antenna, or moving antenna closer to speaking position. As a Shure and Sennheiser dealer, the suggestion(s) I would make would be based on those options. Shure, QLX-D would be a great solid solution- with a UA874US at the receiver, you would have a great signal strength. Of course, the best wireless solution still might not be as good as running a $50 XLR cable...

Side note: Purchasing a solution suggested by a salesperson (as opposed to an acoustical or installation consultant or contractor) is looking for trouble. They commonly want to sell you either what they have in stock at the moment, or what brings them the highest margin, and those products might not be the right solution for your situation.

-Ray

[Eric Lyon]

Ray, below is a link to a pic of the stadium. We fill this during graduation so interference was a issue using a 2.4ghz mic even with the extra antenna's. Would there be a issue at that distance using the IEM's?

https://i.imgsafe.org/31f3e71.jpg

[Ray Aberle]

Well if you get IEMs that aren't running on 2.4GHz (that you identified as your problem) then you should be better off--

[Thomas Lamb]

First let me say I am not anywhere close to a professional in sound. What I am is the person my school system has chosen to find answers to problems with most of our sound needs. This is a fairly long question with a few parts.

This is about stadium sound, our stadium is semi sunken and currently we have 2 - Elements™ 115C 105X60RT with a IPR2™ 5000 DSP for power to the speakers. They are mounted centrally on the pressbox and do a good job to provide sound thru the entire stadium. The first problem is when I have a speaker on the field for example - graduation, it is really hard for them to speak due to the reverb bouncing around the stadium. It takes more than a few seconds for each spoken word to dissipate. Ideas or thoughts about how I can make it easier for the person on the field to speak? I have a podium we could hide a monitor inside. A wireless solution would be best.

Second part of this is about microphones. Its about 250ft from the microphone to the receiver. On a salesman's suggestion we bought a high dollar line 6 mic and receiver. It works decent when the stadium is empty but due to the 2.4ghz it runs on, when I put 1000 cellphones and humans between them the signal is slow and drops out. Other microphones that would be a better solution in this situation?

Let me say thanks in advance.

IEMs would help. It's been a while since I've done a stadium. However, when I do it's typically at a new stadium and there is a dedication ceremony. I always suggest that whomever speaks write down what they want to say and stick to the script. I suggested this to a principal once and received a big attitude. She said "This is norms first time speaking in public!! I speak in front of people all the time I know what I'm doing and I don't need any help" well ok.... I didn't like the lady before this interaction. Sure enough she stuttered all over the place. Write it down!

[John Rutirasiri]

Ray, below is a link to a pic of the stadium. We fill this during graduation so interference was a issue using a 2.4ghz mic even with the extra antenna's. Would there be a issue at that distance using the IEM's?

https://i.imgsafe.org/31f3e71.jpg

Eric, last summer I installed a new sound system at Adlai E. Stevenson HS football stadium (Lincolnshire, IL -- a Chicago suburb).  They had very similar issues to yours:  speech intelligibility and wireless mic RF coverage.

Concerning the speech intelligibility and sound bouncing all over the place, can you post pictures of how the speakers are mounted and aimed?  What is the height?  I think we need some data to start.  Next would be the processor settings, such as high pass filter, parametric EQs and delay (although you only have 2 speakers.)

Concerning the wireless mics, "been there done that" with Sabine's 2.4GHz  As you've discovered, it's just too congested when there's a crowd and becomes unreliable. 

We evaluated Shure ULXD and QLXD but instead went with the old but proven UR4D+ for the distance -- its distance far surpassed the ULXD and especially QLXD in real-world environment. 

For a stadium where you can't predict where the wireless will be, I would go with omni antennas.  Mounted one on each end of the pressbox.  Don't worry that the pressbox is metal -- for us, it actually helped with the omni antennas (behaves kind of like a dish -- just make sure the antenna do not touch the pressbox.)  Even with the transmitter at low power (10mW on the UR2, I think), we got exceptional coverage beyond the stadium grounds.   We used an in-line amp and RG213X cabling to minimize loss.

Feel free to PM me if you have specific questions.

Best,
John R.

[Erik Jerde]

What the previous guys have said is good advice.  Loose the line 6 wireless.  2.4Ghz is hitting you with a few problems.  It's congested with wifi devices, has a smaller coverage distance, and uses more power than a UHF band device.  Get with a local AV integrator who can work with you on antenna placement, cabling, and proper RF gain structure.  Don't buy equipment from them, buy a solution to your problem.  That way it's on them to get you something that actually works, not just sell you what they've got on the shelf.  Maybe avoid the guy who sold you that line 6... unless he offers to buy it back.

Wireless IEMs is probably the best way to help your speakers be smooth without spending a lot of money on a whole new PA system for the stadium.  You do need to find a way to convince them to use them.  Might want to feel out your speakers prior to the event and if there is push back just have them come out and speak sometime prior to the event and see how it works.  If you have multiple speakers you may need a couple IEM systems.

[Stephen Kirby]

Haven't done anything in a football stadium in years but would a small wedge help the presenters?  Just enough for the precedence to cover the reflections in the stadium.  Many people don't like to hear themselves and will back off the mic, but it might be less disconcerting.  Can't imagine how you'd get a series of speakers at an event to use IEMs.  Plus most regular folks have no idea what that is like to hear themselves in their head.

[John Rutirasiri]

The audio delay could very well be due to those Line 6 mics.  Digital wireless mics in the 2.4GHz band do not have deterministic latency...the delays are all over the place.

As others have said, those Line 6 have got to go!  This may solve your problem.

John R.

[Tim McCulloch]

The audio delay could very well be due to those Line 6 mics.  Digital wireless mics in the 2.4GHz band do not have deterministic latency...the delays are all over the place.

As others have said, those Line 6 have got to go!  This may solve your problem.

John R.

He's starting out with 250' of distance between the talker and the loudspeakers, according to the picture he linked above.  That looks a little bit "long" to me, if the football field is 300' long, but after about 80-100ms, it's too much regardless.

The primary problem is that the loudspeaker system was never designed to do what is being asked of it.

[John Rutirasiri]

He's starting out with 250' of distance between the talker and the loudspeakers, according to the picture he linked above.  That looks a little bit "long" to me, if the football field is 300' long, but after about 80-100ms, it's too much regardless.

The primary problem is that the loudspeaker system was never designed to do what is being asked of it.

Tim, agree...I think it's an issue with most high schools.  Often the National Anthem singer or the coach is on the field with the wireless. 

The schools usually don't have the budget to do a proper distributed system like say an NFL stadium, nor are there overhangs to mount such speakers since bleachers are open.  So it ends up being a couple or few speakers on the pressbox or lighting poles trying to cover a vast open area.

When I do STIPA test on a stadium, I'm going from end zone to end zone every 5 yards, down the center and down both sides of the field, trying to simulate where a person might stand and speak.   If the height, toe-in, and angle of the speakers are correct and the system is properly delayed and EQ'ed, when the stadium is full the crowd really helps tame reflections off surrounding buildings (at the expense of significantly higher background noise.)

But the unpredictable, sometimes seemingly random delay of those 2.4GHz wireless mics when there's a 1000 WiFi devices going makes the delay much worse.

John R.

[Ray Aberle]

Sometimes, though, it's just the delay of the system itself. We provided production for a political rally in Seattle on 3/25, at Safeco Field, and the PM at first wanted to tie into the house sound system- until he was told that there's a 6 SECOND delay in the system-- no way was that going to be acceptable to the speaker!

So we ground stacked a bunch of VerTecs and called it a day.

-Ray

[Andrew Brubaker]

I empathize with the OP about Line 6 wireless. I previously had two of their systems and had nothing but issues with them for the same reason: they function in an already populated 2.4GHz range. I have some older Line 6 that works in 900MHz range and have never had an issue. I also now use Sennheiser in the 500-600MHz range and have had zero issues.

Solution: sell off the Line 6 and get a wireless solution that operates in a better band.

[Brian Jojade]

But the unpredictable, sometimes seemingly random delay of those 2.4GHz wireless mics when there's a 1000 WiFi devices going makes the delay much worse.

The line 6 mic spec sheet says that there is a <2.9ms latency in the system, which is pretty typical of a digital wireless mic.  Some mics use a fixed latency so it is ALWAYS exactly the same. The Line 6 may use a variable latency. Their spec sheets don't clarify.  If there are other WIFI devices in the area, the result is reduced range and dropouts, not random latency of the signal.

Having a long delay won't affect intelligibility. It only distracts the speaker's ability to speak.  I've found that it usually takes about 20ms of delay before it becomes a noticeable issue for most speakers.  On a normal stage, you could easily have that much delay from your main stack to the presenter position. Once you get over 50ms of delay, almost everyone has some difficulty overcoming that, especially if they are not prepared for it.

In any case, this amount should not have a significant impact on the performance.  That delay would be similar to having a speaker 3 feet away from the presenter.  The roughly 250ms delay that they are getting from the speaker system on top of the press booth will have a dramatic impact on their ability to speak.  Having a wedge monitor in front of the speaker can help to some degree, as long as the monitor overpowers the delayed sound coming from the main speakers.

Now, the other issue is the overall intelligibility of the system.  If you solve the problem of the speaker being able to speak, and have a system with a lot of echo and reflections, the result will be muddy sound that nobody can understand.  The more echo the system has, the slower the speaker must talk to get their words across.  In many stadiums, the announcements being made are very short, and the announcer takes his time and draws out the words which will overcome these problems.  If you try and have a detailed speech with the same system, it's not going to do the job for you.

If you are doing special events in the stadium, such as a graduation, you would be better suited to bring in a system to be put on the stage for that express purpose than trying to use a stadium system that isn't designed for that sort of thing.

[Tim McCulloch]

The line 6 mic spec sheet says that there is a <2.9ms latency in the system, which is pretty typical of a digital wireless mic.  Some mics use a fixed latency so it is ALWAYS exactly the same. The Line 6 may use a variable latency. Their spec sheets don't clarify.  If there are other WIFI devices in the area, the result is reduced range and dropouts, not random latency of the signal.

Having a long delay won't affect intelligibility. It only distracts the speaker's ability to speak.  I've found that it usually takes about 20ms of delay before it becomes a noticeable issue for most speakers.  On a normal stage, you could easily have that much delay from your main stack to the presenter position. Once you get over 50ms of delay, almost everyone has some difficulty overcoming that, especially if they are not prepared for it.

In any case, this amount should not have a significant impact on the performance.  That delay would be similar to having a speaker 3 feet away from the presenter.  The roughly 250ms delay that they are getting from the speaker system on top of the press booth will have a dramatic impact on their ability to speak.  Having a wedge monitor in front of the speaker can help to some degree, as long as the monitor overpowers the delayed sound coming from the main speakers.

Now, the other issue is the overall intelligibility of the system.  If you solve the problem of the speaker being able to speak, and have a system with a lot of echo and reflections, the result will be muddy sound that nobody can understand.  The more echo the system has, the slower the speaker must talk to get their words across.  In many stadiums, the announcements being made are very short, and the announcer takes his time and draws out the words which will overcome these problems.  If you try and have a detailed speech with the same system, it's not going to do the job for you.

If you are doing special events in the stadium, such as a graduation, you would be better suited to bring in a system to be put on the stage for that express purpose than trying to use a stadium system that isn't designed for that sort of thing.

This is where I was headed.  A 200' microphone cable would "fix" the Line 6 problem, but nothing fixes the rest of what is improper about THIS use of the installation.

Hire in a competent system for the graduation ceremonies.

[Stephen Kirby]

The typical HS grad ceremony on the field is a series of SOS along the track in front of the bleachers.  At the University graduation I recently went to it was multiple VerTec dashes on Genies, but same basic idea.

[John Rutirasiri]

The line 6 mic spec sheet says that there is a <2.9ms latency in the system, which is pretty typical of a digital wireless mic.  Some mics use a fixed latency so it is ALWAYS exactly the same. The Line 6 may use a variable latency. Their spec sheets don't clarify.  If there are other WIFI devices in the area, the result is reduced range and dropouts, not random latency of the signal.

Digital wireless mics don't "use" latency, fixed or variable.  Latency is a characteristic of the signal processing, sampling rate,  A/D and D/A conversion, and in the case of 2.4GHz, how congested the channels are. That 2.9ms latency spec is under typical operating condition, on a clear channel without 1000 kids trying to Instagram.  The Line 6 latency does vary and can be more than 2.9ms when there's a lot of WiFi devices transmitting.  I have the same issue with Shure GLXD. 

2.4GHz digital wireless, no matter what brand, does not possess deterministic latency. Nature of the beast.

John R.

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