power supply usage
Console and power supply grounding
Console chassis ground is electrically connected to:the audio ground, pin-1 of XLR connectors,
the sleeves of 1/4”sockets,and to the terminal CONSOLE GROUND at the rear of the power supply.
The AC third-wire connection in the power supply cable connects the metal chassis of the
power supply to safety ground.
Rack-mounting—the power supply ground may transfer to the rack case through the front fix-
ing screws,though this connection is not reliable.
Sound system use—the grounding requirements may call for the ground link to be disconnect-
ed.This is permissible only when an alternative ground path has been provided.If in doubt seek
the advice of an experienced electrician.
Redundant power supplies
The console power supply can be considered the single most important component in an entire
sound system.If a power amplifier,a signal processor or a console input goes down in the mid-
dle of a show,the show can still go on.But if the console loses its power supply,the show is over.
For this reason,it is always good practice to incorporate redundant power supplies for mixing
consoles used in professional sound reinforcement applications.
This should be considered a high priority even when using a very reliable power supply.In even
the most carefully designed sound systems,each component runs the risk of failure at sometime
or another.
Crest Audio uses two methods for attaching redundant power supplies to consoles.In both
methods,the two (or more) power supplies should be kept on while the console is in use to
insure a smooth transition in the event that one shuts off.
If one power supply drops in voltage or shuts off completely,the other unit takes over without
any interruptions or audible glitches.As an added precaution,the two (or more) power supplies
can be fed by separate AC lines.This will guarantee that the console does not shut off if one of
the AC lines goes down.
Multiple power supplies in-series
Crest Audio X-Series consoles use this method for backup.Since each power supply includes
voltage switching circuitry,more than two units can be hooked up in series. A DC-Link cable
ties the power supplies together.Normally two supplies are used for redundant (fail-safe) oper-
ation,but there is no real limit to the number of supplies that can be used.A daisy-chain can be
constructed using DC-Link cables to tie each supply to the next.At the end of the chain, the
last power supply uses the normal DC power cable to tie the entire power supply chain to the
Console.
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Power supply 5