Broadcasting the Colorado Symphony Orchestra

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On Location, March 2010

Microphone paradise

On a tour of KUVO, Pappas' assistant Will Barnette unlocked the equipment cabinet and revealed a Neumann lover's paradise, with M150s, U87s, a U67 and more. For the Yo-Yo Ma concert, which was held in the Boettcher Auditorium, Pappas turned to a prototype Neumann microphone, the KM133D, a digital microphone. The microphone uses an M50 titanium capsule, which Pappas said is ideal for many classical applications.

Pappas sets levels before the concert.

Pappas sets levels before the concert.

"It's mounted in a sphere, so at low frequencies the microphone is an omni. As we get above 1kHz the microphone develops a cardioid pattern. Then above 16kHz it's a hyper-cardioid," explains Papas. "With classical work, that allows you to be real creative. Being omni at low frequencies allows us to integrate some of the room tone. The other cool thing about omnis is they are extremely flat in their frequency response. Now, the Germans won't tell you this, but the capsules on those digital mics, or the M150s for that matter, are 3dB down at 2.5Hz. We have lots of low frequencies, and that's good, because you don't want to have rolloff that's going to look back anywhere into the audio passband. You want to keep that as far out of the audio band as possible, because the minute you have a rolloff, you have a phase shift. Omnis are cool for that, but the problem with omnis is they are omnis, so you want something with some directivity at high frequencies, because it allows you to aim the microphones into the orchestra and use that directivity to help bring out certain sections of the orchestra.

Pappas used a total of five in front of the stage, using tape to mark the placement of each microphone to within a quarter of an inch, since they had to take them down after each morning rehearsal. The microphones were placed 10'3" above the stage, aimed slightly down at a five degree angle. Barnette and Joey Kloss helped Pappas place the microphones and take them down each day after rehearsal.

The digital microphones have an NMC DMI-8 eight-channel control box that feeds into a Mac running RCS software. The control box provides phantom power, in this case 10V at 0.5A, because the mics have a gain stage, A/D chip and DSP chip inside the bodies.

A mic named Fritz

From the computer, via the RCS software, many parameters can be set, including compression and limiting, though Pappas used neither. The control box also sets the sample rate, which in this case was 24-bit/44.1kHz. The reason for the sample rate is the console, in this case a Digico DS-00 broadcast console, which runs at 44.1kHz.

Making final settings on the surround encoder

Making final settings on the surround encoder

"We have every imaginable facility on the console, but we don't use it," laughs Pappas. "Let me qualify that; for big symphony projects, we don't use any EQ, dynamics processing, or the eight stereo reverbs. It's a big level control and router, because we route stuff to get it to the broadcast guys."

In addition to the KM133Ds, Pappas used a stereo dummy head, the KU100, which he and his team have affectionately nick-named Fritz, back in the hall hanging from the ceiling 10 meters above the floor to create the surround rears. Fritz was aimed at the back of the hall, instead of at the orchestra, to get more of the room integrated into the surrounds.

"Fritz is an analog box and has standard (analog) outputs," says Pappas. "We try to not run analog mic cables very long. The cabinet right above Fritz is a Grace 802 unit with a built-in A/D converter that outputs AES. We feed that AES signal down 400' of CAT-5 cable. We use CAT-5 because it is very low capacitance, and capacitance is the number one killer for AES. You don't necessarily need it shielded because it's a balanced signal coming off 7.5-8V peak to peak."

- continued on page 3

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