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VOCIA AMPLIFIERS VA-2060, VA-2060e, VA-4030, VA-4030e REAR PANEL
Output Fault Detection
The Amplifier monitors (supervises) for faults on speaker connections using a combination multiple out-of-band (inaudible) high frequency
tones for end-of-line detection, and DC current for ground fault detection. For end-of-line detection, one or more (up to 15 maximum) ELD-1
units must be connected to the end/s of the speaker line. End-of-line and ground fault detection may be individually enabled/disabled in the
Vocia software. To ensure correct operation of fault detection it is necessary to follow these guidelines:
• When an ELD-1 is being used in a Vocia system it is important that the Amplifier Output Setting in the software matches the Hard-
ware Output setting selected on the physical amplifier (8Ω, 4Ω, 25V, 70V or 100V). See the Software Help file for more information.
• Recorded audio messages or audio content with continuous or swept tonal components (e.g. alert tones) and any content with
significant high frequency harmonic content should be band limited (>24dB/octave) at 15 kHz during recording. Note that program
content that is distorted due to poor recording techniques may contain excessive high frequency harmonics.
• Signal level adjustments within a Vocia system should be set so as to minimize clipping. Severely clipped signals may also affect the
out-of-band fault detection tones.
• The use of speaker cables that inherently attenuate high frequencies is not supported (e.g. screened cables). Speaker cables must
maintain frequency response to the end of line of less than -3dB @ 20kHz at with respect to 1kHz.
• Speaker cables longer than 500 feet may prevent correct operation of ELD and Ground Fault monitoring capabilities. An advantage
of Vocia is that amplifiers may be easily distributed close to speakers, thereby minimizing long runs of expensive and potentially
lossy speaker cable.
• Highly capacitive speaker lines or loads may prevent correct operation of the ELD detection system.
• Legacy monitored speaker circuits that use capacitors and resistors or similar methods must have all legacy monitoring circuitry
removed for correct operation of the ELD detection system.
The amplifiers use DC current to detect whether there is an erroneous ground connection placed on either or both speaker wires. The
detection circuit will declare a fault for a resistance to ground of 50kΩ or less. To prevent false ground fault readings, the DC resistance to
ground of speaker circuits must be 100kΩ or higher (either speaker wire to ground).
• For EN54-16 compliance, one or more ELD units must be fitted. End of Line detection and Ground Fault Detection must be enabled
in the Vocia software.
