A year ago I reviewed the Audio Toolbox (ATB) audio measurement device by TerraSonde (PAR, 12/99, p. 76). I was impressed enough with it that I bought one, which I use almost every day. I looked forward to the Plus model, which has even more useful features, including a built-in rechargeable battery system.

The ATB Plus ($1,699)definitely looks and feels more serious with its rugged anodized aluminum, cast-aluminum and steel case. The Plus was made more ergonomically friendly, with a handle on the right side and the encoder controller on the left, permitting access to all functions with only the left thumb. Just as with the standard ATB, rotating and pushing the controller does it all.

The ATB Plus chassis measures 12 inches, by 6 inches by 2 inches, and weighs less than five pounds, including its rechargeable battery. The display has twice the viewing area of the standard Toolbox's 64 x 128 pixel resolution. It is backlit, making it easier to read from a distance.

A contrast control fine-tunes the display for any reading angle or light condition. The display lighting can be configured to stay on any programmable length of time from 0 to 999 seconds through the setup menu. Each time you turn or push the encoder wheel, the backlight turns on for the selected amount of time. Battery life is shortened with the backlight on. Under normal conditions, the backlight is not necessary, turning it off extends battery life up to three or four hours between recharges.

The balanced XLR and unbalanced RCA inputs, as well as the power switch and battery compartment door with the AC adapter/charger input, are located on the bottom of the unit. All the connectors and switches are recessed, keeping them well protected.

On the top of the unit are XLR, RCA and 1/4-inch phone outputs as well as MIDI I/O and the BNC mic input. The Plus comes with PC and Mac serial interface cables for upgrading or changing software and storing memories to your computer. The cables interface with the ATB Plus via the MIDI I/O jacks and to your computer with a serial port connector. The BNC connector allows for the supplied microphone to plug directly onto the ATB Plus or through a supplied six-foot Canare BNC cable. I prefer to mount the mic on a stand and hold the ATB Plus while operating it, which may be more accurate.

The latest and most comprehensive software available for the Audio Toolbox Plus is the Contractor Software, which comes standard with the Plus ($150 upgrade on the standard Toolbox). Almost all of the functions have additional or upgraded features including ANSI octave and one-third-octave filtered pink noise.

The Instrument Tuner and Tempo Computer, which are included with the standard software, are omitted with the Contractor Software due to the expanded test features. If you wish to downgrade to the standard software to get the music-related features, there is no charge and you can reload the Contractor Software at anytime.

The battery system is sealed lead acid (SLA) and has a built-in charging circuit PCB mounted on top of the battery itself. Charging is done with the supplied wallwart and can be done while the ATB is in use, or a second SLA battery can be charged without being plugged into the ATB. It is recommended that the charger stay connected while the ATB is not in use as the battery cannot be
damaged due to continuous charging, like some rechargeable batteries.

The ATB Plus comes in a foam-lined plastic carrying case with a place for the microphone, cables, power adapter and a spare battery (an extra battery costs $99.95).

The Audio Toolbox Plus is also available in a rackmounted version with a built-in AC power supply and also ships with Contractor Software.

The Audio Toolbox Plus from TerraSonde is a good value when you consider all of the in-depth test functions you get and its upgrade capability.

Contact: TerraSonde at 303-545-5848; 888-433-2821; www.terrasonde.com

Tom Jung, founder of DMP Records, is Pro Audio Review's technical consultant.