By Full Compass LiveIt’s easy to take power for granted: plugDefinition:
A connector, normally male and attached to a cable. into a wall, electricity flows...don’t worry, be happy!
But all power is not the same, and your ACDefinition:
AC (Alternating Current): Current whose electrical flow alternates between positive and negative quadrants, and whose magnitude varies periodically. Alternating current is used in most commercial power transmission, and is also the basis of audio or video signals. power source may have unwelcome, unsavory hitchhikers along for the ride—like voltageDefinition:
Also called electro-motive Force (EMF). The "charge potential" or pressure of electrons that causes current to flow in a circuit. spikes, noise, and fluctuating voltages. The spikes can attack gear over time by stressing out components, noise can get into your system, and brownouts can do everything from reducing amplifierDefinition:
1. A device that increases the voltage or power of a signal. 2. In music performance, a device such as a guitar amplifier that includes speakers and controls to increase the sound level of acoustic or electric instruments. power to damage sensitive equipment. And there are even issues with the AC power’s waveformDefinition:
A graphic picture of a wave.. We assume it’s a sine waveDefinition:
A pure-sounding tone, whose energy is concentrated solely at its fundamental frequency. Commonly used in testing audio devices, and music synthesis., but harmonics can be present. If they’re of sufficient amplitudeDefinition:
The volume (Amount) of a signal, electrical, optical or acoustic., these can create Eddy current losses in transformers, which causes them to run hot.
There are two main solutions to deal with power issues. Power conditioners filter out noise, suppress spikes, and clean up dirty power. Uninterruptible power supplies (UPSDefinition:
(Uninterruptible Power Supply) A battery-powered, AC power backup device that takes over in the event of a power failure. The power last for a limited amount of time, depending on the power consumption of the unit(s) being powered. Usually conditions AC power as well.) often provide similar features, but include a heavy-duty battery and AC inverter that provides power for anywhere from seconds to minutes when the power goes down.
Don’t mistake power conditioners for the barrier strips at office supply stores that offer surge protection. Those strips do indeed offer a minor degree of protection, but aren’t anywhere near sufficient for pro audio or video installations. So, let’s consider five reasons why clean power is important—and present some solutions along the way.
1. Clean power means your equipment will have protection against several kinds of damage.
You’ve heard the phrase “death by a thousand cuts”—to power supplies, it’s more like death by a thousand spikes. They can cause issues in diodes, capacitors, and even transformers, which can lead to failure; a severe enough spike (like from a lightning strike in the general area, not even a direct hit) can cause an outright failure. Furthermore, when the power comes back on after going out, the simultaneous inrush of current to multiple devices can cause power dips and spikes. You don’t want this, so it’s important to protect against spikes.
2. You’ll have higher audio and video fidelity.
A lot of points in sensitive audio and video circuits connect to ground. But if noise and garbage get on the ground line, which can happen with dirty AC power, that noise can work its way into your circuits. Those who’ve decided to clean up their AC power are often surprised to find that side effects include lower noise levels and clearer videos. There are even conditioners optimized for specific devices that are very sensitive to power problems, like flat panels and projectors. A good example, the SurgeX SA-82 FlatPak surge protector/power conditioner (Fig. 1), handles 8 amps, up to two devices, and includes over-voltage shutdown with automatic reset. It’s also designed to keep a low physical profile (good news for sound contractors), by mounting flat on walls or ceilings.
3. Even a basic unit makes a difference.
Of course, you can throwDefinition:
The distance between a lighting or sound source and its object. as much money as you want at any problem. But fortunately, even relatively inexpensive units can take care of surges and noise. Furman’s M-8X2 (Fig. 2) is one of the most popular choices for general-purpose protection. It has a proven design, sports eight rear-panel protected outlets and one front-panel switched outlet, and handles a maximum of 15 Amps. Given the cost, it’s an affordable insurance policy.
Higher-end units may have a balanced isolation transformerDefinition:
A passive electromagnetic device that uses one or more coils of wire to isolate or split signals. Also may convert impedance and voltage levels. May be used to eliminate ground loops, reduce Rf interference or crosstalk. that basically decouples your gear from the AC line to give superior noise rejection, more advanced filtering, metering, and the like. For example, stepping up to Furman’s PL-Plus DMC (Fig. 3) adds the ability to safely power itself and connected gear down when voltage conditions become unsafe, but there’s also more sophisticated filtering and metering for both line voltage and current draw. All those features are great, but even if you’re on a tight budget, a basic power conditioner is a bargain compared to the cost of repairing, or replacing, your gear.
4. An uninterruptible power supply is essential with computers.
Not just “nice,” or “desirable”...but essential. Some units combine both protection and an uninterruptible power supplyDefinition:
A device (internal or external to another device) that provides power for active circuitry. Can be AC, DC or battery-powered. (UPS) that keeps a backupDefinition:
1. (verb) To create a copy of existing software to insure against loss of the original. 2. (noun) The copy of the original software. battery charged. If the AC power goes away, the battery kicks in to provide power for a finite period of time. This allows for an orderly shutdown of computer-based systems until power returns.
Also consider that when doing firmwareDefinition:
Software encoded into an integrated circuit, which unlike volatile memory, remains until altered and whose data persists after power cycles. updates, it’s imperative that power not be interrupted. Although sometimes you can just start the update over, a firmware update reaches so far into a system’s basic code that dataDefinition:
Information used by a computer in order to arrive at a decision. Although this is a plural term, it's often treated in the singular. corruption may not even allow a device to bootDefinition:
Short for Bootstrap Loading. To boot a computer means to start it up ,and place its operations under control of the operating system.. Putting a computer, terminal, and broadband device on an uninterruptible power supply can save you a lot of grief over the years.
However, it’s important to choose a UPS with sufficient power. Today’s computers tend to be power-hungry; a unit like the Middle Atlantic UPS-1000R (Fig. 4) accommodates 1000VA/750W, which is a good place to start. But it also has several other essential features, like making sure the AC is a pure sine wave without harmonics, integration with control systems by including RS-232Definition:
(Recommended Standard 232) A 3-wire serial communication data protocol, usually with a DB9 connector, and providing one-to-one communication.. Used for remote control of devices and transferring data. and analogDefinition:
A signal that is continuous in nature, as opposed to being defined as a series of discrete numbers (or elements) as found in digital signals; electrically "analogous" to an acoustical signal in the air. I/ODefinition:
(Input/Output): 1. A pair of connections that provide input(s) and output(s). 2. The connections that link a computer to devices outside the computer., and a hot-swappable primary battery to minimize downtime—even the 9 ft. power chord is designed to minimize stray magnetic fields.
If your needs are a little less stringent, the Tripp Lite SMART 1200LCD UPS (Fig. 5) provides four minutes of run time at full load (1200VA/700W), and twice as much at 350 Watts. When running on battery, it produces a pulse-width modulated sine wave—which is good enough, considering all you want is the ability to shut things down quickly.
5. Consolidation neatens your setup.
By definition, a power conditioner or UPS will include multiple outlets. In the case of a UPS, these will usually be divided into outlets that run off the battery, and outlets that have only surge and spike protection. Being able to plug your gear into a centralized, professional, rack-mountable power conditioner beats using extension cords and barrier strips.
However, you may also find you have a lot of low-power devices, and that the four or so surge-protected outlets in a UPS aren’t enough to accommodate them—even though there’s no way your devices draw enough power to cause anything near an overloadDefinition:
Causing a device to exceed its capability, usually undesirable but used for an "overdrive" effect in music. Also called 'Blooming" in classic recordings. See Overdrive. condition. For this, the Tripp Lite RS-1215 (Fig. 6) is ideal. It has 12 outlets, 6 front-facing and 6 rear-facing; with the rear panel, several of the outlets are offsetDefinition:
1. A difference in timecode position between two machines. 2. A positional difference between clips in an audio or video editing program. to accommodate “wall wart” transformers.
Admittedly, power supply conditioning is not a glamorous topic...until you start conditioning your power supply and find that equipment runs better, unexplained glitches are less common, and your tools last longer. Back when the Alesis ADATDefinition:
ADAT (Alesis Digital Audio Tape): An S-VHS-based, 8-track digital audio recording format, syncable with additional units to add tracks in groups of 8. took over the world of digitalDefinition:
A signal or data expressed as series of the digits 0 and 1, typically represented by values of a physical quantity such as voltage or magnetic polarization. recording, there were often complaints on forums about “unreliability.” Interestingly, those who used power conditioning and uninterruptible power supplies didn’t have the same problems.
Although a lot has changed since the days of the ADAT, one thing hasn’t: AC power can still be dirty. But most importantly, it’s still worth cleaning up.