Real World: The Building Block Approach
A straightforward look at test and measurement equipment
Audio Control Industrial Iasys
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What it is: The Iasys (as in “I assist” - get it?) is a stand-alone portable 3-D measurement system. Its most outstanding feature is that it focuses on giving those who do not want to become instrumentation experts the answers they need to set up a sound reinforcement system. |
More from John: The brainchild of Robert Reams, this unique analog device uses fuzzy logic to provide the user with: calibrated SPL, frequency response with coherence that blanks out non-minimum-phase areas that cannot be equalized, recommended limiter settings determined from the onset of driver non-linearity, recommended crossover frequencies, delay offset of drivers, polarity indication, and signal generation.
Gold Line TEF-20
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What it is: Based on time-delay spectrometry, an invention of Richard Heyser (AES Fellow and research scientist for Jet Propulsion Laboratories), the Gold Line TEF-20 is a fairly portable PC-based 3-D system. Its strong point is noise immunity during testing, as well as the variety of unique measurements that it can make. |
More from John: Depending on the software purchased, it provides calibrated SPL, a semi-anechoic FFT-based frequency and phase response, energy decay time, impulse response, Nyquist plot, Heyser spiral, up to 1/12-octave RTA, RT-60, signal generation, harmonic distortion testing, driver impedance curve, time/level analysis, NC curves, STI, RaSTI, 3-D time-energy-frequency “waterfall,” speaker polar response, and polar ETC which pinpoint the level, time arrival, and direction of acoustic reflections.
DRA Laboratories MLSSA
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What it is: MLSSA is a DOS-based program that is most at home in the lab. |
Its measurements include SPL, FFT-based frequency and phase response, energy decay time, impulse response, RT-60, signal generation, harmonic distortion testing, driver impedance curve, time/level analysis, NC curves, Speech Transmission Index (STI), Rapid STI (RaSTI), 3-D time-energy-frequency “waterfall,” time coherence, acoustic center, speaker polar response, and Thiele-Small parameters.
More from John: MLSSA, pronounced Mellissa, has been a long-time favorite of speaker system developers and has primarily been used in a laboratory/bench environment. It pioneered the Maximum Length Sequence measurement technique from which it derives its name. It is a PC-based system using full-length ISA cards installed into the PC’s unused motherboard slots.
Ivie IE-33
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What it is: This hand-held 2-D measurement system is based on a Compaq PDA and comes with a calibrated measurement mic. In this very small package it provides up to 1/6 octave RTA, calibrated SPL, seat-to-seat level variation, energy decay time, polarity, oscilloscope, time/level analysis, NC curves, and signal generation. More from John: Less than a year on the market, the developers hope to add stable phase measurement to the IE-33 feature set for the next generation. Gold Line has a similar product with compensating equalization for the built-in mic in lieu of a calibrated microphone. The size-to-capability ratio is staggering for the IE-33. |
Meyer SIM System II
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What it is: The SIM System II can provide FFT-based semi-anechoic frequency and phase response with coherence, 1/24-octave transfer function, 1/6-ocatve RTA, impulse response, S/N ratio, and harmonic distortion. Version 2.3 can simultaneously display three separate measurements in real-time. More from John: SIM is a hallmark for quick set-up of touring systems with multiple speaker zones. It is the 3-D product that introduced Source Independent Measurement (SIM) to the sound system industry. And, it can switch inputs from up to (64) measurement mics and at 60 pounds without a video monitor can be a bit cumbersome for “portable” sound system measurement. |
SIA SMAART Live
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What it is: Utilizing a source independent measurement technique similar to Meyer SIM, SMAART is a 3-D, PC-based measurement platform. SMAART Live measures SPL, semi-anechoic FFT-based frequency and phase response, spectrograph, which is a “top-view” of a 3-D waterfall display using color to indicate level, impulse response, time/level analysis, NC curves, RT-60, STI, polarity, delay time, signal generation, and transfer function. |
More from John: Easily the most popular and best dollar value of the current offerings, SMAART Live also accommodates external device control of over 40 equalizers and DSP processors including the recently introduced Lake Technology Contour (For more, see page 62 of this issue).
NTI Minirator/Minilyzer
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What it is: The Minilyzer offers a 1/3-octave RTA, an oscilloscope, SPL, level metering , harmonic distortion, VU & PPM metering, polarity, and signal balance error. It has an on-board mic, but this is used only for polarity testing. All other non-electronic testing must use a separately purchased measurement microphone. More from John: The Minirator/ Minilyzer is comprised of a pair of hand-held, stand-alone devices that make up a very compact 2-D signal generator and an analyzer duo. The Minirator generates all the signals needed for the Minilyzer, which does all the analyzing. Either can be used with other equipment. |
Terrasonde Audio Toolbox Plus
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What it is: Toolbox Plus will measure SPL, 1/3-ocatve RTA, 1/12-octave FFT, energy decay time, RT-60, time/level analysis, NC curves, RaSTI, polarity, oscilloscope, time code tools, signal generator, frequency counter, level meter, dynamic range, and harmonic distortion. It also functions as a monitor amplifier, cable and phantom power tester. More from John: A stand-alone, portable measurement device, the very attractive Audio Toolbox Plus is just that, a whole toolbox full of tools. |
Though not as tiny as the PDA-based units, it has the largest amount of measurement functions offered in the industry. (For John’s in-depth report on Toolbox Plus, see the April 2003 issue of Live Sound.)
Also of note in the test and measurement field...
Morset Sound Development WinMLS 2000
Lars Morset of Norway has developed WinMLS 2000 from an academic research
tool in acoustics. It is a 3-D PC-based measurement tool that has extensive
capabilities. It has, in one form or another, most all of the measurement
capabilities of the more advanced measurement systems reviewed here, with
the exception of the SMAART/SIM windowing technique, TEF polar, as well
as polar ETC capabilities.
The user interface is currently being refined to make it less of an academic
tool and more industry friendly. It has deep acoustics capabilities that
are more esoteric than what is needed for general sound reinforcement
work, but is a very powerful tool for those who take the time to get over
the learning curve. Look for a more user-friendly version in the future.
Acoustic Design Ahnert ESRA
Dr. Wolfgang Ahnert, the developer of EASE acoustic simulation software,
will soon be releasing ESRA, a new measurement platform that will interface
with EASE and will also incorporate TEF measurement capability.
Steve McManus, Gold Line’s software engineer, has collaborated in the
development of this product. Re-quired hardware will be PC-based with
a high quality mic preamp package. Stay tuned...
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Lake Technology Contour Gets SMAART |
An AES/EBU stereo digital input has also been added to Contour, permitting interface with a digital mixing console without the need for additional converters in the signal path. This could be the tip of the iceberg in terms of integrating digital processing technologies with available test and measurement tools. Again, stay tuned...
Live Sound Technical Editor John Murray is a 26-year industry veteran, working for EV, MediaMatrix and TOA. He has presented two AES papers, chaired three Syn-Aud-Con workshops and is a member of the TEF Advisory committee and ICIA adjunct faculty. We encourage you to send technical questions to John at jmurray@livesoundint.com
October 2003 Live Sound International