Neural Audio 5225

February 1, 2006

When Radio One first installed HD Radio transmitters for its stations in Philadelphia and began broadcasting a digital signal, the engineers at its stations were impressed by the lack of multipath and increased stereo separation. The question was, “Would this be enough benefit to catch the ears of listeners?” Several Radio One stations were adding 5.1 to their broadcasts, but it wasn't clear how the Philadelphia stations would handle this conversion within their all-analog facility. Beyond that, the group had only recently completed construction on an analog facility, and was not ready for a digital conversion.

An engineer's view

After some investigation I spoke with Ken Wallace, the chief engineer from our sister stations in Detroit. He told me that Detroit recently added Neural Audio 5.1 capability to one of its studios. When he told me that the stations had begun producing 5.1 digital content almost immediately after the installation of the Neural processors, while using their existing studio consoles, I was intrigued. I contacted Neural Audio to find out how the Neural system would mesh within our existing stereo facility.

Neural explained that its approach allows producers to work their usual magic with standard editing software (adding a few more channels, of course), and then the Neural system downmixes the content to a watermarked stereo file as the final step. The output of the Neural 5225 Downmix can then be treated as normal stereo for storage on our servers, where it is played back later for broadcast to our listeners. The files also maintain surround encoding for easy portability in exchanging stereo files through e-mail or FTP with our stations in other markets. At the consumer receiver end of the chain, the music and content can be listened to in mono, stereo, matrix surround, or 5.1 surround using the Neural Upmix decoder.

Performance at a glance
32kHz to 48kHz sampling rate
Uses watermarking technology
Transports surround with two-channels
Remote control via RS-485 and USB
Accepts external word clock

Neural arranged to come to Philadelphia to help with the installation in our production studio. Our studio uses a ProTools Digi002, which natively was not designed for 5.1 production. With the addition of an RME ADI8 Lightpipe to AES converter, we had more than enough channels of I/O to accommodate the extra channels needed for surround sound. We then attached the Neural 5225 Downmix via the RME converter. This configuration allows individual tracks to be routed from Pro Tools to each of the 5.1 audio channels within the Neural 5225 Downmix. The Neural 5225 Downmix then returns the stereo watermarked version of the 5.1 mix that can be recorded onto a separate track in Pro Tools or directly bused to our Wheatstone console for storage in our automation system.

To monitor our newly created 5.1 content, we installed a Neural 5225 Upmix unit. This box was wired to the stereo console monitor outputs and then directly to the Blue Sky amplified speaker system. This was an easy way to monitor 5.1 without defeating the Wheatstone's microphone mute and control room volume control. With the addition of two Neural 5225 boxes and some speakers, we were ready to go.

A producer's view

As production director of Radio One Philadelphia, it took a few minutes to get used to the newly added surround channels. Initially, I created a checklist to remind me of import and I/O settings until I got used to working with six channels rather than two. But it didn't take long for me to understand the added benefit of Neural Surround Sound.

It was clear to me when two of the top sales execs were escorting a couple of ad agency clients though the studios. I had just finished a promo and they were blown away by the energy, motion and movement of the piece. They had no idea that you could create that kind of sound on the radio. Surround Sound gives new life and attention to sweepers, promos and production.

Technically, it is a breeze to set up a session in Pro Tools using Neural Surround Sound. After opening a new session, (I have a template that starts with eight tracks including four mono tracks), I move to the setups menu and open I/O Setups. In the output mode I open Import Settings. Neural also places a surround.pio setting in Pro Tools, which is then highlighted and opened. Then, I name the outputs in the interface with the corresponding channel.

Setting up sessions

For instance, the center speaker would be the mono voice tracks, the front speakers would be tracks four, five and six, the rear speakers would be track seven — left surround — and track eight — right surround. I pick and choose which tracks are designated with each speaker. You can have as many right and left surround speakers as you need. The only negative for me right now is that my current Pro Tools template only allows mono channels to be routed to the rear surround speakers, but I've been told that this can be easily reconfigured. For now it does, however, work wonders for crowd noises, allowing them to creep up from the rear speakers, just like in a real concert.

Neural Audio

After setting up the outputs I add the final track. This is done in Pro Tools by selecting the File menu and choosing Add Track, One Track, Stereo, Aux 1. The input of this track is “Watermark Stereo;” the outputs are one and two. By using this approach, everything that is sent, even to clients, is watermarked with Neural Surround Sound.

Imagine crowd noise, sound effects and production elements moving from front to back and left to right. Sweepers swirl in sound, making the calls stand out. This is the impact programmers will demand and expect from digital radio. It was easy to use and brought an added dimension to my work.

Once digital radio gets off the shelf and in cars, servicing the listeners with surround sound production will be the norm. Having a system that works easily with Pro Tools and delivers incredible sound can give you a running start within digital radio.

DePolo is chief engineer of Radio One Philadelphia, which includes WRNB, WPHI-FM, and WPPZ-FM. St. James is the production director.

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