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Now in its second
generation, TerraSonde’s Audio Toolbox Version 2 is a collection
of DSP-based maintenance tools that any studio will find useful. The original
Audio Toolbox Version 2 is compact and lightweight and covers a wide range
of useful functions. Other versions include a rackmount model and a handheld
“Plus” version.
The Toolbox performs so many functions that it would be difficult to detail
them all, so I will describe the primary functions and discuss the unit’s
overall performance. As acoustics is my specialty, I have concentrated
on those functions.
 THE
HARDWARE
The standard box measures 5.5x9.5x2.5 inches, weighs only 2 pounds and
is made of molded plastic with a 2.4x1.75-inch backlit LCD screen. A single
knob switches between programs and is used to make parameter adjustments
and data entries. A calibrated microphone is built into the unit, but
you can also connect any measurement mic. The box seems rugged, although
I typically wrap the unit in bubble-wrap when shipping. It can be powered
by a removable battery pack (six AAs) or a wall wart power supply.
Inputs and outputs are mounted on the sides of the box. Balanced XLR,
1/4-inch and RCA left and right inputs are available. There is one MIDI
input and two MIDI outputs, along with a single headphone jack, a small
built-in speaker and single RCA, 1/4-inch and XLR outputs.
THE SOFTWARE
The main menu offers four functions: Acoustic Analysis, Test Functions,
Session Helpers and Utilities. Six submenus under the Acoustic Analysis
menu include Sound Level Meter, Real-Time Analyzer, Energy Time Graph,
Reverb Decay Time, Polarity Tester and Noise Criteria.
The Sound Level Meter function measures loudness in standard dB SPL units.
It is a true RMS measurement, using ANSI Type 1 standard display time
averages with A, B, C and flat weighting networks. Averaging modes include
Slow, Fast, Impulse, Peak and LEQ. LEQ is used for computing equal-weighted
SPL averages over a long period (for you OSHA types). The internal or
external mic can be selected, with two sensitivity ranges available. Measurement
data is presented as both a numeric readout and a bar graph. Full control
of the signal generator is available directly from the Sound Level Meter
screen. Selectable waveform types include sine and square (frequencies
are adjustable) and white or pink noise.
The Real-Time Analyzer looks at the sound spectrum in 1-, 1/3-, 1/6- and
1/12-octave bands, with good resolution although the screen is tiny. Data
can be viewed in a full-bandwidth window of 20 to 20k Hz as well as a
low-frequency 10-to-332Hz window, a useful view that covers the area of
most critical analysis. A variety of averaging times is provided for exponential
or equal-weighted time averaging. The display is adjustable in 5dB increments
with a 35dB window range from top to bottom, offering a wide picture of
spectral activity. The low end of the scale is 25 dB with the maximum
being 170 dB. One cool “extra” field gives a variety of useful
additional information, such as the band that has the highest momentary
level (Hz max), the full-band SPL level (dB SPL), the A-weighted SPL (dBA
SPL), or the C-weighted SPL (dBC SPL). To assist in setting surround 5.1
monitoring systems, two more fields measure dBL SPL and dBm SPL. dBL shows
the average SPL level of the subwoofer bands (as defined by Dolby Labs),
25 to 125 Hz, while dBm SPL shows the average SPL of the nonsubwoofer
bands. I tend to rely more on the spectrum display for subwoofer calibration,
but this feature offers a handy correlation. Forty nonvolatile memory
locations for storage can be recalled in the Toolbox or transmitted to
a PC or Mac for printing. Data parameters for the recalled memories can
be adjusted for critical analysis.
The Energy Time graph displays the initial delay time from the sound source
and the subsequent decay pattern in the room. This is useful for finding
room reflections, identifying resonances and aligning delay systems. The
data can be viewed as time or distance, with the measurement units displayed
in milliseconds, feet, inches, meters or centimeters. (I did not find
a frequency display effective.) The capture window is adjustable for the
measurement units. For example, in milliseconds, the window ranges from
15 to 960. This is handy for controlling the amount of detail you need.
Moving the cursor across the screen displays the time (or distance) for
that point numerically, along with the dB level relative to the maximum
value received. This lets you find room reflections in units of distance.
While the program is running, you can zoom in on areas of the chart for
more detailed analysis (15ms window). You can store 40 graphs in nonvolatile
memory with the same functionality as the RTA.
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to Page 2
Reprinted with permission from Mix Magazine, July, 2000
© 2000, Intertec Publishing, A Primedia Company All Rights Reserved
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