Mar 9, 2011 2:23 PM,
with Bennett Liles
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Roaring crowds, blasting music and all the excitement of athletic competition makes installing a stadium sound system all the bigger challenge. Daktronics made it all work in multiple sports venues at Indiana University and design and field engineer John Carlson is here to give us all the details for the sound system at the University’s Memorial Stadium. That’s coming right up on the SVC podcast.
John thanks for being here with me on the SVC podcast all the way from Brookings, South Dakota, here in Atlanta it’s chilly but I have to say I’m glad I’m not in South Dakota right now.
Yeah I’m sure you are. It’s about a -19 with the wind chill here today. [Timestamp: 1:01]
Well it’s probably a good thing you’re not out there on those athletic fields we’re going to talk about. You had a tremendous installation on the campus of Indiana University. A number of athletic venues there got big new Daktronic scoreboards and that’s probably the first name anybody might think of in big outdoor scoreboards and displays but on this one Daktronics also handled the new audio systems. Memorial Stadium is the football venue there, how does the new Daktronics sound system in Memorial Stadium work? That was a major installation.
That’s right, well this was a large stadium like you said so in this stadium we needed reach maximum SPL so we used a Bessel array as a point source system along with some side fills for the main speaker system. On the front end we had to do quite a bit of updating so we installed a large LS9-32 mixer and that accepts quite a few inputs. [Timestamp: 1:52]
OK and where is the mixer located?
The mixer is located on a tabletop in the announcer's control room so the announcer and the audio system controller would be in the same room. [Timestamp: 2:01]
OK that always sounds like an interesting monitoring situation when you have a sound system that covers that much area and its outside. You’ve got this roaring crowd and being inside this announce booth and being able to hear what you’re doing out in the stadium it must take some getting used to and maybe it’s no place for a novice operator.
We’re lucky in this particular installation they actually have a hired-on professional man to run this system so working with a professional system like this and a professional operator they’re able to achieve the best possible performance on the system that they have. [Timestamp: 2:39]
And what kind of sources are fed into this sound system obviously microphones but we what all do they do there?
Quite honestly this system can accept any source that you want to feed into it basically the only thing that needs adjustment would be the type of interface that you would use. But currently right now their taking sources…feeds from our actual video server computers but mainly in this system they actually have a production truck down at the base and that production truck actually sends an audio signal up to the main audio control room. [Timestamp: 3:13]
Ok we’re talking about announcer mics and during halftime shows there are things happening on the field and they need mics down there and there may be even live music from time to time.
Yes there’s actually four wireless microphones receivers within the system that are built in and those systems actually work very well with this system so they have two handheld microphones and they have two belt pack transmitters that they can use for their referees also they have a quick effects style computer up on the front of the announcers control booth. [Timestamp: 3:45]
And I’m sure they can playback pre-recorded music for cheerleaders and things. So how is the signal actually fed out to the speakers from the control room? Is this a fiber optic system?
To actually run the sound system itself from the control room, yes that is a fiber optic transmission with an analog backup. What we’re utilizing is CobraNet signaling and we transmit that CobraNet with fiber optic so they have fiber optic Ethernet transmitters on both ends. That way we have full system control because we can control our amps from the control room that are actually in those speaker cabinets themselves over that same fiber optic link. [Timestamp: 4:22]
What do you have going on for speakers out there in the stadium? What components do they have?
There’s actually 24 12in. drivers in there for low frequency and then there’s nine proprietary Daktronics mid-high boxes in that system itself and those are all self powered so the amplifiers are in proximity really close to the speakers themselves. [Timestamp: 4:42]
Well that’s great with the fiber optic transmission then since you don’t have to worry about ground loops and hum from things getting power from different places.
Exactly that’s why we go with the fiber optic transmission and if anything were to happen to take down that fiber optic transmission we can quickly switch over to an analog back up which is just a simply twisted pair copper cable that goes out there. [Timestamp: 5:04]
And when you’ve got a system this complex and physically spread out you’ve got to have some way of spotting trouble very quickly and enabling you to be proactive and watching everything. I understand there’s some hefty diagnostic features on the control end of this system.
Yes each one of the self-powered speakers itself has an amplifier and those amplifiers being connected with the Ethernet cable all the way to the front end they give us the opportunity to actually diagnose each amplifier and we can even program the amplifiers if need be from the front end. Also on the front end we have diagnostics over each one of our wireless receivers. We also have full-link functionality over our mixer and we have full link over our digital signal processor on the front end and the computer that’s actually connected to all this on the backbone of the front end actually has a touchscreen with a custom interface panel I created to control that signal processor which is actually located on the front end. [Timestamp: 6:03]
So a lot going on behind the scenes but very easy to operate on the user interface.
It’s extremely easy to operate for as complex as it sounds but the operator there is a professional operator so he fully understands and utilizes the full potential of the system. [Timestamp: 6:18]
What kind of amplifier do you have running all this stuff?
These are a proprietary amplifier designed and manufactured for Daktronics by an outside supplier but they are outdoor-weather rated and self-powered units for each one of the speaker boxes. [Timestamp: 6:32]
You’re using CobraNet conveyance for this but on the mixer what’s the actual interface? Do you have slide in cards or is the CobraNet interface external?
The mixer itself is sending an analog signal into a London BLU-80 signal processor and that processor has output CobraNet cards on it that go out to this system. [Timestamp: 6:53]
What was the cable running phase of this project like? Did you have any special…say architectural problems?
As far as running cable for this system is was all pretty simple by the time I got to the job all of the details were worked out. We were fortunate enough as Daktronics we installed the new video board and the sound system so all the cabling from the actual sound system to the control room was easy because it was mostly a new installation. As far as within the building we were able to utilize some of the existing cabling which was actually good and install a couple of new cables to the new equipment that was installed to make this systems complete. [Timestamp: 7:3]
So any problem with the control room layout? What actually goes into installing the mixer for a sports venue of this size?
Well I wouldn’t say there was any problems. It was exactly clean but that goes with the job so our biggest task here was to take what they had for a control room and clean it up. So we ended up removing the rack that they had there and taking all of the existing cabling that we would be reusing and rerouting it to our new control rack. We also replaced their mixer with our new mixer, which was much larger, but it ended up giving the operator much more space underneath the counter and also on top of the counter and there was no cables or rats' nests on top of the counter or behind it. We actually utilized on this mixer a custom-made mixer snake that took all the inputs and outputs and directed them directly over into the control rack. That way interfacing could be done within the control rack to keep it neat on top of the countertop. [Timestamp: 8:28]
OK always a good idea to plan for later expansion and make it quick and easy. In a stadium of this size how important is it for the audio operator to have a clear sight line to the field? I don’t know how much you can really see from that distance.
Well with this system when I first came into the project it looked like the operator had almost no clear visibility of the field or the board itself but with us being able to move around objects in this control room and clear it up he was able to have a full view of the field and a full view of the display although the operator does not clearly need this because he does have an intercom system right there at his disposal and all the announcing is done by somebody else. He can actually run the entire system just off vocal commands. [Timestamp: 9:12]
Right and I guess during regular season football games they pretty well have a set routine worked out where they know what they’re going to do and when. You mentioned wireless mics and that’s a pretty long distance to be transmitting. What’s your secret for capturing good signal from the wireless mics at the stadium?
When we use wireless systems in a stadium this large obviously we do away with the sticks that would normally come with the microphones and we take cable off the units and actually remotely locate the two panel antennas. In this case we put the antennas outside so they’re in a clear line of sight view of the field. [Timestamp: 9:49]
And everything from the antennas runs down on what type of coax?
We use a 50Ω coax. [Timestamp: 9:54]
OK describe if you would the function of the control room rack equipment so that you can control all of the wireless and DSP features of the system.
This is actually a rack mount professional computer that’s installed in the rack permanently. And with this rack-mount computer there’s actually, like I said, a rack-mounted touchscreen so the user can access all the wireless components, the mixer itself and the amplifiers all from one point within that control room. [Timestamp: 10:21]
Well it sounds like they got a good start and the system’s fairly new but they’ve had a chance to break it in and see how it works.
Right and this is a professional operator that’s using this system so he was very happy to see this new system and I’d say he could walk into this system and within a couple of hours he could operate this system as good as he’d have to for the rest of the season. [Timestamp: 10:41]
Well it sounds like a tremendous upgrade for Memorial Stadium the football venue at Indiana University and John thanks for here for Part 1 and in Part 2 we’re going to get into Bill Armstrong Stadium, the soccer field, and talk about the sound system you put in there but for now thanks for being here for Part 1.
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