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Articles Tagged Bill Whitlock

  • Tuesday, April 16, 2013
    Eliminating Potential Trouble & Getting The Noise Out Of A System
    image
    Bill Whitlock 04/16/13 06:01 PM,
    “A cable is a source of potential trouble connecting two other sources of potential trouble.” The humor in this statement may be lost on those who regularly assemble sound systems. But a reality of sound systems is that a signal accumulates noise as it flows through equipment and cables. And once noise contaminates a signal, it’s essentially impossible to remove it without altering or degrading the original signal. For this reason, no system can be quieter than its noisiest link.… View this story
    Filed in: AV • Feature • Blog • Study Hall • AV • Digital • Installation • Interconnect • Power • Signal • Sound Reinforcement • System

  • Thursday, September 06, 2012
    The Truth About Balanced Audio Interfaces In Systems
    system power
    Bill Whitlock 09/06/12 05:56 PM,
    An analog audio interface may be unbalanced or balanced, depending only on the impedances (to ground) of its two signal conductors. In balanced interfaces, both conductors have equal (and non-zero) impedances. A balanced interface also requires that driver, line, and receiver all maintain balanced impedances to ground. They are therefore extremely potent in preventing all kinds of noise coupling, in fact, so powerful that many systems, such as telephone networks, use them instead of shielding as the main noise reduction… View this story
    Filed in: AV • Feature • Poll • Study Hall • AV • Interconnect • Signal • System • Audio

  • Thursday, June 07, 2012
    Invaders From Outer Space: Electromagnetic Radiation & Interference
    ac power
    Bill Whitlock 06/07/12 03:09 PM,
    Electromagnetic interference, often referred to as EMI, is a degradation of the performance of a piece of equipment or system caused by electromagnetic radiation. Electromagnetic radiation is the travel of alternating electric and magnetic fields through space at 186,273 miles (about a billion feet) per second, or the speed of light. A wavelength, as shown in Figure 1, is the physical distance traveled by a wave during one cycle. Figure 1: High-frequency magnetic and electric fields travel fogether as a… View this story
    Filed in: AV • Feature • Study Hall • AV • Power • Signal • System • Audio

  • Monday, April 30, 2012
    Power Lines: Determining When “Isolated Grounding” Is Needed
    a/v
    Bill Whitlock 04/30/12 02:37 PM,
    If electrical wiring, from main breaker panel to outlet, consists of Romex and plastic J-boxes, an “isolated” or “technical” ground system is already in place. This is the case In most, but not all, residential wiring. However, when wiring consists of metallic conduit and J-boxes, as in most commercial buildings, an isolated safety-grounding scheme can sometimes reduce audio system noise. It is most applicable in situations where conduit may come in contact with building steel, water pipes, gas pipes, or… View this story
    Filed in: AV • Feature • Study Hall • AV • Power • Signal

  • Wednesday, March 21, 2012
    Connecting Unbalanced Outputs To Balanced Inputs—And Vice-Versa
    unbalanced inputs and outputs
    Bill Whitlock 03/21/12 06:33 PM,
    Based on my years of helping customers solve interfacing problems of all sorts, connecting unbalanced outputs to balanced inputs, and vice-versa, certainly ranks among the most common and confusing of tasks for system integrators. Basically, two issues must be dealt with. The first involves the different signal operating levels between unbalanced (consumer) and balanced (professional) equipment. The second involves making the actual connections to transfer the signal while avoiding “ground loop” noise problems. Signal operating and reference levels are significantly… View this story
    Filed in: AV • Feature • Poll • Study Hall • AV • Interconnect • Power • Signal • Audio

  • Wednesday, October 19, 2011
    Pesky Ground Loop Problems Plaguing You?
    power
    Bill Whitlock 10/19/11 09:12 AM, 2 Comments
    When a system contains two or more pieces of equipment that are grounded, whether via power cords or other ground connections, a “ground loop” will likely be formed. See Figure 1, below. Although ground loops often involve power line safety ground connections, disabling them is both highly dangerous and illegal. However, devices called “ground isolators” can be inserted in the signal path to break the loop safely. This approach attacks the problem at its fundamental roots, while tampering with safety… View this story
    Filed in: AV • Feature • Poll • Study Hall • AV • Installation • Interconnect • Power • Signal • Sound Reinforcement • System • Audio

  • Monday, August 29, 2011
    Dirty AC Power? Where To Lay The Blame For Noise Problems
    image
    Bill Whitlock 08/29/11 04:36 PM, 0 Comments
    The idea that “dirty” power causes audio system noise problems has a nearly irresistible intuitive appeal - and there are dozens of companies ready to cash in on this widespread but mistaken belief. For example, here is a quote from a well-known manufacturer of power conditioning products: “Today’s residential systems contractors face unprecedented challenges where high resolution, trouble-free operation is required. From inducing AC ground loops, video hum bars, static bursts, damage from AC line surges and variable audio and… View this story
    Filed in: AV • Feature • Poll • Analog • AV • Installation • Interconnect • Measurement • Power • Signal • Sound Reinforcement • System • Audio

  • Monday, June 06, 2011
    Further Eliminating Ground Loop Related Problems With Proper Use Of Isolators
    audio system power
    Bill Whitlock 06/06/11 02:41 PM, 0 Comments
    A ground loop can exist in any system that contains two or more pieces of grounded equipment, whether via power cords or other ground connections. An isolator is a device that passes signal while interrupting the path for the ground loop current. They are not filters, and must be inserted in the signal path at a specific location, which is found through troubleshooting to be effective. A properly installed isolator virtually eliminates hum, buzz, or other noises caused by ground… View this story
    Filed in: AV • Feature • Poll • Study Hall • AV • Installation • Interconnect • Power • Audio

  • Monday, May 16, 2011
    Method Not Madness: Correctly Troubleshooting Audio Interfaces
    unbalanced inputs and outputs
    Bill Whitlock 05/16/11 08:13 AM, 0 Comments
    Previously (see here and here), we’ve looked at how unbalanced audio interfaces work, as well as how grounding-related noise can actually couple into the signal path. Of course, under fortuitous conditions, audio systems may be acceptably quiet in spite of poor techniques. But physics will ultimately rule and noises may later appear for no apparent reason – remember, noises that disappear by themselves also tend to re-appear by themselves! Most systems consist of more than two pieces of interconnected equipment,… View this story
    Filed in: AV • Feature • Poll • Study Hall • AV • Engineer • Installation • Interconnect • Power • Signal • Sound Reinforcement • System • Audio