Field Report: Vorsis AP-2000

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The Vorsis AP-2000 is a five-band AGC/compressor and 31-band limiter with specialized algorithms for bass and voice band processing. Its output feeds will accommodate just about any flavor of FM/HD Radio operation. Transients are gracefully controlled without compromising the long-term texture, levels, frequency response and harmonic integrity of a station's signature sound. The AP-2000 includes the latest development from Vorsis, a division of Wheatstone.

This one does it by the numbers, packing the math power of 19 digital signal processor (DSP) engines. The processing workload is split into a multitude of parallel processes. Independent analog and digital transmitter paths contain their own respective 31-band limiter, VBMS and Voice Master algorithm. Despite its complexities, the AP-2000 amazingly reconstitutes all this information — time aligned analog to digital, phase aligned analog L+R vs L-R and phase coherent across the audio spectrum.

The big bottom

Spy on your program director's car or office radio and it probably has the EQ extremes cranked up. Everyone wants more bass, but that can mean more intermodulation distortion. To that end, the Vorsis Bass Management System (VBMS) was developed to separate and process the bass range independently. The VBMS boosts base while mitigating the effects of IM through mathematical control of harmonics.

Membership into a secret society is not required for full access to the AP-2000. Every feature and control is present on the front-panel LCD display or through a Windows-based software application.

Performance at a glance
31-band fine grain processor
Five- or three-band AGC preprocessor
Oversampled look-ahead limiter or specialized clipper
Voice Master voice distortion management
Ethernet-based remote control
Eight input GPI preset triggers
32kHz - 96kHz digital input
FM/HD Radio delay of up to 10 seconds

Control area

Analog and AES3 audio inputs provide source diversity for fail-over protection in the event of prolonged silence to either path. There are analog outputs with or without de-emphasis, AES3 digital outputs with selectable pre/post diversity delay and with/without de-emphasis. Balanced composite stereo is present on the XLR jacks for a clean, noise-free signal into an FM exciter equipped with balanced inputs. There are also two unbalanced composite stereo outputs on BNC connectors. Jacks are provided for SCA injection and control.

The general purpose interface (GPI/GPO) has up to eight opto-isolated inputs and four outputs that have tested well in high RF environments. A typical application might include remotely bypassing the AP-2000 during EAS tests with a logic return on the transmitter remote control confirming the system status. Convenient front-panel connections include a headphone jack and a USB port for a mouse. A five-port Ethernet hub inside is brought out to RJ-45 jacks on both the front and rear panels.

Getting started is easy. The manual has an 11-step guide to getting on the air. Suggested default settings for most parameters are listed for a good starting point. There is a list of about 70 ready-made presets for various programming formats. Finding that perfect setting comes down to choosing a compromise between clean and loud.

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