Balanced AC… The Heart of the Matter

ATK balanced power distro

As with most audio systems, the power distribution sub-system is one of they keys to a rig’s performance. Like your own heart, it is responsible for pumping the lifeblood to all the other parts of the system, and any weakness in this area will detract from potential performance capabilities. The folks at ATK have taken their AC distribution a step further than most, deploying a “balanced” power scheme throughout. If you are not familiar with this technology, I suggest you spend some time investigating it.

In my personal experience, I installed an Equi-Tec balanced power system for a tour I was on a few years ago. There was the usual bevy of compressors, equalizers and such wired to a PM4K. After the installation the difference in noise level was astounding! You could crank the headphone amp on the 4K all the way up and the closest thing to a hum or buzz was buried in the noise of the console … which itself was also much quieter. It was dramatic.

In ATK’s case, this symmetrical power system is utilized throughout the rig. Their power cables are seven conductor with a single ground and six hot legs with 60V potential to ground on each. When you utilize two of the hot legs, you get 120V potential between them. A standard AC system has 120V between one hot leg and the neutral. The neutral has zero volts referenced to ground, so you have all of the 120V potential on one leg. Think of it like you do an audio circuit. When you use a balanced (as opposed to unbalanced) connection between devices with a + and a – conductor, any noise induced in to the circuit is cancelled at the input op-amp because it has equal and opposite polarity. This AC system functions in the same way, reducing AC line noise to very low levels.

Line Array Loudspeaker Systems

Scott Harmala with standard ATK arena system amp rack

Before the return of the line array system, ATK developed its own loudspeakers like many other companies in our industry. A large format concert box called the C6 is still part of their inventory. Along with their own loudspeakers, ATK also utilized the EAW 860 series when that became popular in the mid 90’s.

It was during this time period, however, that they had an opportunity to test sixteen boxes from France called V-DOSC. And while ATK did not purchase this technology right away, they recognized the powerful potential that existed for this style of loudspeaker system, and a year later purchased their first line array. Thus began an era at ATK where the line array became king, and today it is used on 80% to 85% of the shows they do. Over time, ATK purchased other line array loudspeakers, as well, most recently from JBL in the form of VerTec.

Bill Brumgard, Senior Lab Tech

Scott Harmala says, “V-DOSC is great. It opened all our eyes to the power of a well-designed line array system and it still works great. But it has not changed in 10 or 12 years. VerTec is awesome. It solves many rigging and electro-mechanical issues. We have large inventories of both. VDOSC has developed a name that everyone knows, but I'm sure that VerTec will develop its own recognition. Of all the other next generation line array systems that I have seen, I believe that VerTec is the best compromise.”

Scott also speaks very highly of the latest software package from JBL. It is utilized to design and deploy the VerTec system in a way that takes advantage of the unique properties inherent in this technology. By entering dimensional information from the seating area, and defining the type of array you want to hang, this software is able to accurately model the performance of the system within the room. It also provides load data regarding stresses placed on the rigging. By employing this software, ATK is able to accurately plan a “firing solution” (as they refer to it!) for each event, and then assemble the correct arrays in short order, and align the system to the room with minimal chance of error. The company is currently developing a hardware solution that allows them to receive telemetry from the cluster to confirm its attitude within the venue, ensuring that all of the planning and calculation is implemented correctly, achieving the desired coverage results.