AES PNW Section Meeting Report

AudioControl Industrial IASYS - November 21, 1996 


On November 21, 1996, two dozen members and guests of the Section heard a 
presentation by Tom Walker, of AudioControl Industrial, describing the new 
Iasys electro-acoustic analyzer.

The original idea for the analyzer came from Robert Reams; insights into the 
design of the device were gained when he read and re-read the papers of the 
late Dr. Richard Heyser. He then developed the analog and digital hardware 
with Dwight Freeman, Robert developing the analog portion and Dwight the 
digital.

Dwight also developed the software. Dennis Griffiths worked with Dwight to 
insure the hardware and software worked well together on all of Iasys' 
numerous applications. 

The Iasys has 4 major distinctions compared to other audio analyzers, 
according to Walker:

	It is designed to give answers, not interpretable data;
	It gives the user a better sounding sound system fast;
	It is something you can use every day; and
	It allows you to precisely calibrate tools you already have.

He said existing analyzers are created for engineers and PhD's to use, not the 
average mixers at live events or sound contractors installing permanent 
systems.

The device performs four tests:

1) Crossovers
It will recommend the appropriate crossover frequency 
for each component in multi-way systems, and then displays the relative level 
of each bandpass, all operating one at a time in the acoustic environment in 
which the system will be operating, making the bandpass levels simple and easy 
to adjust.

2) Delay and Polarity
It will measure and display the distance from a tested component to the 
microphone, as well as the relative distances between 2-4 components. It also 
will test the acoustic polarity of the components, and can do so from a 
distance as great as several hundred yards (assuming minimal interference from 
wind), which allows you to check "mystery systems" without having to climb to 
where the speakers are located.

3 Coherence and Equalizable Frequency Response
(Quoting from the brochure) "In real time this test  measures the arrival 
times of each individual frequency [1/12th octave steps] and displays in a +/- 
percentage how close it is to the acoustic distance gathered in Test Two. With 
the simple push of one more button Iasys will display a frequency response 
curve showing only the frequencies that can be equalized."

This test highlights problems in component and array placement or arrangement, 
room reflections, crossover/delay/equalization problems, and provides a means 
of verifying probable intelligibility of the system. There is not a 
correlation at this time to other intelligibility verification systems such as 
RASTI, however.

4) Limiter Setting
It will tell you where to set limiter thresholds, and does so by examining 
each component for the onset of thermal limiting. The system or bandpass 
limiter would then be set to limit just before that onset.

Demonstrations of each of the tests were given at the meeting using two small 
speaker systems, and IASYS seemed to do what it was designed to do.

It was an interesting and thought-provoking meeting.

Reported by Dan Mortensen, AES PNW Chair