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Author Topic: Need some pro suggestions please  (Read 3658 times)

John Rutirasiri

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Re: Need some pro suggestions please
« Reply #10 on: April 05, 2016, 09:32:43 am »

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.



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Ray Aberle

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Re: Need some pro suggestions please
« Reply #11 on: April 05, 2016, 10:49:40 am »

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
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Andrew Brubaker

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Re: Need some pro suggestions please
« Reply #12 on: April 05, 2016, 12:03:21 pm »

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.
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Brian Jojade

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Re: Need some pro suggestions please
« Reply #13 on: April 05, 2016, 04:09:45 pm »

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.
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Tim McCulloch

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Re: Need some pro suggestions please
« Reply #14 on: April 05, 2016, 04:43:11 pm »

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.
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Stephen Kirby

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Re: Need some pro suggestions please
« Reply #15 on: April 05, 2016, 05:43:19 pm »

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.
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John Rutirasiri

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Re: Need some pro suggestions please
« Reply #16 on: April 05, 2016, 08:02:34 pm »

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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Re: Need some pro suggestions please
« Reply #16 on: April 05, 2016, 08:02:34 pm »


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