Side by Side: On-air Audio Processors
Apr 1, 2013 7:45 AM, By Chriss Scherer, editor
Audio processing: It’s what gives a station its signature sound. Because of that, a station’s processor setup is often the super secret of a station and protected like the gold in Ft. Knox. In the analog days, everyone had that little processor key and you might be tempted to sneak a peak, although the knob settings were only a small part of the secret process.
With digital signal processing, there’s no need to open the box and make the ultra-secret tweaks of capacitors and resistors. For the most part, all that control is now available through the unit’s control interface. Levels, thresholds, signal routing, crossover frequencies and more can be adjusted to minute levels.
But the current wave of processors has also overcome the problem of achieving loudness at the cost of losing quality. Advances in limiting and compression techniques allow some of the musicality to be preserved. With so much source material using data-reducing algorithms, there’s less audio stuff to squeeze. Even the transmission paths for online and HD Radio use data-compressed encoding.
The flagship processors of these manufactures also provide dual processing paths to feed an analog and digital transmission path. This simplifies setting the two chains to sound similar and preserve that signature sound.
BW Broadcast DSPXtra-FM
With a six-band limiter, an integrated Ariane RMS leveler and look-ahead final limiting, the DSPXtra-HD uses 22 DSPs for processing power. The processing core includes parametric and shelf bass enhancement, along with composite clipping with pilot protection. Dual processing paths (analog and digital) make the DSPXtra-FM two processors in one. The FM analog path has a multi-band distortion-controlled clipper, while the second path, tapped via analog and AES digital output connectors, incorporates a bit rate optimized, look-ahead limiter. Front panel LED audio metering and front panel USB interface aid setup and operation. Several versions of the DSPX are available with varying features.
This FM and FM/HD Radio processor features an all-digital, DSP-based design. Gain-riding AGC, five bands of dynamics compression and equalization, stereo enhancement and sub-bass augmentation, plus the Inovonics PIPP limiter are included. A high-performance stereo generator includes active and metered RDS combining. The David IV can accept analog and AES digital inputs, and has two separate composite/MPX outputs in addition to analog and AES line outputs. The line outputs can be configured for either FM or digital radio transmission characteristics. Control is via the front-panel graphic display and jog wheel, or by TCP/IP control over all parameters with a PC and supplied software.
The Omnia.11 was created to provide a solution to distorted audio processing, while still delivering a competitive, loud signal. The Density Detector enables the system to properly handle hyper-compressed content. The ultra-low IMD multiband limiter system, coupled with smart gain reduction algorithms, enables the limiters to sound transparent and natural. All AGC and limiting algorithms employ an auto-acceleration/deceleration mechanism, which tunes out perceptible inter-modulation distortion.www.omniaaudio.com
Orban Optimod-FM 8600
The 8600’s dramatically improved peak limiter technology decreases distortion while increasing transient punch and high-frequency power handling capacity. The main goal is to make FM analog broadcasts more competitive with the cleanliness, punch and open high frequencies of the digital media against which FM analog transmissions now battle. In addition to the new clipper, the 8600 offers the same extensive feature set as the 8500. Except for the AGC, the analog and digital chains are independent and separately adjustable. The digital radio channel features a new peak limiter.
Wheatstone AirAura X3
The third-generation AirAura X3 spectral audio processor offers improved bass tools, an improved sweet-spot technology algorithm, more EQ options, and a newly developed FM clipper technology resulting in truly impressive sound quality and loudness. New features include backoff controls for each band of the AGC, new analysis features, and enhanced security functions. AirAura X3 also has improved 31-band limiters, new analog output routing features, and a standard WheatNet-IP audio interface for seamless integration into the Intelligent Network.
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