I have such warm memories of my first audio spectrum analyzer. It was in a box the size of a small television–a tube television, that is. The screen of the analyzer was a matrix of red LEDs that turned on or off to indicate signal level at 1/3-octave frequencies across the spectrum. It worked very well and was easy to read in dark clubs, though it wasn't very useful in daylight. I guess you could say it was portable because it came with a small carrying case for transport, but it weighed about the same as I did in those days. It ran strictly on 120 volts AC and employed a separate measurement microphone that connected via XLR cable. I wonder if those warm fuzzy feelings came from the heat that thing threw off the top of the rack… In more recent years, there've been the ubiquitous Radio Shack Sound Pressure Level (SPL) meters. The one with the analog meter (#33-3050) is starting to look like an antique. For an extra 10 bucks, the digital version (#33-2055) looks way cooler and can hold a peak SPL in memory. These meters are probably the two most popular pieces of test gear in our industry. How often do you walk into a venue and see one of them sitting atop the mixing console? Six out of 10? They can tell you much about the way you and your band work, not to mention make you aware of how long your ears are being exposed to a given SPL. And they're less than 50 bucks.
My, how times have changed. Right now, I am holding a 31-band spectrum analyzer in the palm of my hand. Literally. And this device–a Phonic PAA3–also measures reverb time (RT60), SPL, voltage levels from 5 millivolts to 80 volts, dBu and dBV. It has memory registers for storing RTA and reverb time analyses, and can average those results. A USB port allows it to communicate with a PC for upload and display of audio measurements on the PC screen in real time. It costs about a tenth of what that old spectrum analyzer cost.
The Phonic and Radio Shack units are just the tip of the iceberg of what's available for handheld audio measurement. Sophisticated instruments are becoming affordable and compact, making them suitable for work even on the club level. If you're interested in simply measuring SPL, meters are available from Galaxy Audio (CM-130), ATI (ATSLM100) and Nady (ASM2). DAS Distribution's TES 1352A Programmable Data Logging Sound Meter features accuracy of +/- 1.5 dB, 0.1 dB resolution, auto-ranging and the ability to store 16,000 readings with date and time stamp.
A variety of audio test devices are available from Gold Line, including their unique FB23 Feedback Detector. The FB23 helps you identify the frequency of feedback by lighting an LED at the offending frequency so that you can use a 1/3-octave EQ to correct the problem. The company's APT2 phase and polarity tester determines absolute polarity/ phase of any part of a speaker system, while their GL60 calculates a room's reverb time.
Looking suspiciously like handheld computers are the IE-33 and IE-35 audio analysis systems from Ivie Technologies. The IE-35 is a second-generation audio measurement instrument running under Windows Mobile 2005 and capable of functions such as realtime analysis (RTA), SPL, strip chart recordings of sound level over time, polarity check, oscilloscope measurements, RT60 and Noise Criteria (NC/NR) measurements. The IE-35 features an internal test signal generator and a full color display. Ivie's IE-33 is capable of similar audio measurement functions while running its software under Pocket PC.
Those engineers who constantly find themselves setting up myriad wireless mics and personal monitors will be interested in the Models 103, 104 and 105 handheld RF counters from B&K Precision. These meters are designed to measure frequency and period of RF signals over various bands. The 103 measures analog RF from 1MHz to 3GHz, the 104 measures 10Hz to 3GHz (analog) while the 105 measures analog and digital RF ranging from 30MHz to 2.8GHz–all with 0.1Hz resolution.
Sencore–a name well established on the test bench–is now offering their SoundPro Series for handheld use in the field. Their SP395 Audio Integrator features an FFT analyzer, RTA, SPL meter, frequency counter, cable tester, polarity check, RT60 measurement and polarity check. It runs for five hours on batteries and can help installers calculate time delay between speaker clusters.
Sencore's SP295 is aimed squarely at sound contractors featuring RTA, SPL measurement from 35 to 125 dB, Noise Criteria (NC) evaluation of background noise, signalto- noise and impedance measurement. The SP295's Sound Study Graph has the ability to plot average or peak SPL measurements over a period of one minute to 24 hours, and can store 40 plots in its memory.
Designed specifically with live sound engineers in mind are the Audio Toolbox series from TerraSonde. Their Trinity Series includes the ATB-3 monochrome and ATB-3C color analyzers. Unique to the ATB-3 is the ability to simultaneously measure audio, generate pink noise, monitor input via headphones and pass the input through the built-in USB port to a computer. The ATB-3 measures SPL, time-averaged sound level, noise dosimeter, RTA and FFT analysis and includes an internal lithium-ion battery for five hours of portable run time.
So there you have it–audio test gear in the palm of your hand. How you use it is up to you.
In addition to being the Front of House engineer and tour manager for Blue Öyster Cult, Steve "Woody" La Cerra teaches aspiring audio minds at Mercy College in White Plains, N.Y. He can be reached via e-mail at Woody@fohonline.com.
