Meeting Photos 

AES PNW Section Meeting Report

The PNW Section worked to make AES membership a "value added" deal by presenting one of the most valuable topics in audio as an extended evening workshop. "The Top Ten Signal Interconnection Myths" was presented by Bill Whitlock of Jensen Transformers. AES members and any student were admitted free, while non-members paid $25. All attendees were required to preregister, and a full house of 50 attendees - about 1/4 of which paid - met in the Mackie Designs training room in Woodinville, WA on November 19, 2002.

Mr. Whitlock is among a handful of internationally known experts on grounding and shielding. He has designed pro audio and video electronics for 30 years. In 1989, after seven years with Capitol Records, he became president of Jensen Transformers. His paper on balanced interfaces, which appeared in the June 1995 JAES, has become the most popular ever printed there. Other writing includes the "Clean Signals" column in S&VC magazine, three chapters for Glen Ballou¹s "Handbook for Sound Engineers," as well as numerous application notes and magazine articles. Bill holds several patents including the InGenius® balanced input circuit and a high-speed feed-forward ac voltage regulator. He is also an active member of the AES and the Institute of Electrical and Electronic Engineers (IEEE).

As if the term "ground" weren¹t confusing enough by itself, many practices and beliefs surrounding signal interfacing in audio, video, and data systems are rooted more in myth than in science - many of them are reinforced in respectable textbooks. The presentation examined, and hopefully dispelled, some common myths on these ten subjects. We will not attempt to reiterate the information presented, but here are the Whitlock Top Ten:

1. Earth grounding — is the safety of the 3rd prong due to earth grounding?
2. Zero-impedance wire — is there such a thing?
3. Shielding unbalanced cables — how effective at reducing noise pickup?
4. Which end of a balanced cable shield to ground?
5. Signal symmetry versus "balance" — what rejects noise?
6. Single op-amp balanced input "dilemma" — is it really balanced?
7. Audio cables as "transmission lines" — do they require termination?
8. Impedance matching — do load and source need to match?
9. Equipment itself causing noise problems — how common?
10. Vulnerability of digital interfaces — are they immune to these noise problems?

Attendees were to expect a fair amount of basic electronics and physics, and to know basic electronic diagrams. Many comments by attendees indicated the balance of beginner instruction and in-depth technical explanation was perfect.

Our special thanks to Mr. Whitlock, who donated his efforts to specifically benefit the AES, and to Mackie Designs, who donated their facility.

— by Gary Louie, AES PNW Section Secretary