Meeting held January 25, 2003
On Saturday January 25, 2003, the PNW Section held an all-day workshop on FFT analysis of rooms. Over 55 people signed up in advance for the 6 hour workshop and luncheon, with many staying for an optional dinner and evening "anything goes" session. The free workshop (with no-host meals) was co-sponsored with the University of Washington's Center for Digital Arts and Experimental Media, which secured the UW Physics Department's Geballe Auditorium for the event. With such a diverse topic with many measurement methodologies, this meeting focused on the TEF20 system. The PNW Section hopes to hold more such workshops to continue education in other aspects of this topic.
Both local and national presenters lectured and demonstrated.
PNW Committeeman Mark Rogers, Director of AV design at Seattle consultants The Greenbusch Group, began with some introductory review of what, how, and why we measure audio. He concluded with an audience participation non-instrument based Alcons test where a word list was read to the attendees and the attendees wrote down what they thought they heard. test.
Daniel Casado, Seattle-based manufacturer's representative , audio engineer and educator, continued with more needed concepts. He reviewed some of the basic math needed to converse in these measurements, such as radians, waves and wavelength , frequency and introduction to the Fourier transform.
A group "brown bag" luncheon was held in the lobby, then the group reconvened for the afternoon session with Blair McNair and Bruce Main. Blair is the Director of Engineering for Spectrum Design Group of Oklahoma City OK and worked for the TEF division of Crown for several years, teaching their test and measurement classes. He chairs the TEF advisory committee. Bruce is a principal at Vector Inc., as a manufacturer's representative, a sound system designer and TEF advisory committee member.
Blair dug into the nitty-gritty and had extensive demonstration equipment. He started with basic elements of sound, SPL, inverse square law, reflections, diffraction, reverberaton and RT60. The alphabet soup began with the introduction to the FFT (fast Fourier transform), and extensive demonstrations of the Energy Time Curve (ETC) on the TEF (time-energy-frequency) analyzer. Other analysis techniques were mentioned but could not be covered this day, such as Time Delay Spectrometry (TDS), (SMAART) and Meyer SIM (source independent monitoring). After a midafternoon break, Blair continued, zooming in on ETC curves, demoing speaker arrangements with reflective paths, showing laser interferometry pictures of drivers, Nyquist plots, the Heyser Spiral, polar ETCs, speaker dispersion and time alignment.
The PNW door prize drawing awarded NAMM master directories to Steve Peterson, Rick Smargiassi, Doug Wicker and Steve Goegebauer. Charlie Atwell and Steve Douglas won tape measures marked in frequencies (instead of inches!). The grand prize of an AudioControl Industrial Rat pack cable tester was won by Tom Zobrist.
An optional no-host group dinner was held in the lobby, featuring delivered pizza and Chinese food. Afterwards, many stayed until 9:30pm to continue discussion of any and all FFT topics and many "war" stories, including Blair's stories on a Navy aircraft carrier.
Reported by Gary Louie, AES PNW Secretary
Last modified 2/5/2004.