Roger Williams III is a systems designer for MAS Audio, a longtime NSCA, ICIA member and Syn-Aud-Con grad, and is a regular contributor to Pro Audio Review.
Atlas sound has been in the commercial audio product manufacturing business since 1934. Best known to sound reinforcement companies for their rugged microphone stands and horn speakers, they are almost a one-stop shop for just about anything needed by the installer — from volume controls to ceiling mount speakers, power distribution and rack cabinets. Every Atlas dealer is familiar with their product binder — about as thick as a phone book, testifying to the enormity of their product line.
Features
Fast Facts
Applications Sound reinforcement for installations
Key Features Small footprint, current and audio sensing circuits, pole mount
I was sent their new compact power amplifier, the PA702, to evaluate. The amplifier is a two-channel unit offering 70 watts per channel at eight ohms. It has a unique design facility that allows the installer to affix the amplifier to a video projector mount pole, making it attractive as zone localized audio reinforcement for audio-follows-video applications. Another useful feature is a current sensing circuit which senses current draw from an always on AC outlet on the PA702. When a projector plugged into this outlet is powered up it automatically turns on the power amplifier, turning this into a one-button operation. Or, by reconfiguring the rear mounted dip switches you can activate the audio signal sensor circuit, which similarly will “wake up” the amplifier from sleep mode.
When I mentioned the unit is compact, at 8.5-inch wide by 13.5-inch deep by 1.75-inch high, you can fit two side-by-side on a single (optional) rack shelf. The “BASH” amplifier design incorporates a switching power supply and class AB output stage, greatly increasing efficiency, thus enabling higher power output in a smaller package.
A look at the front panel of the PA702 reveals recessed screwdriver adjustable left and right channel gain controls, treble and bass controls, left and right channel signal indicator LEDs, limiter LED, power indicator LED and power switch. The back panel has IEC AC power line receptacle with integrated mains fuse holder, un-switched Edison style AC outlet, left and right unbalanced RCA input connectors, left and right balanced Phoenix input connector, left and right Phoenix speaker connector, dip switches for activating the above mentioned turn-on options as well as stereo-mono input selection and high pass filter, and audio/AC sensing attenuators. On the top of the unit you will see a recessed 2-inch hole, which completely passes through the unit. This is where the pole mount that facilitates the clamping assembly is located.
Product Points
Plus
Compact
Unique Features
Good Sonics
Minus
None
Score An amp with high power-to-size ratio that incorporates useful power-up features.
In Use
I recently had a project that required localized distributed sound for a classroom video projector. After specifying the ceiling speakers and installing them, I endeavored to attach the PA702 to a Chief RPA-U projector mount, which would ultimately hold a Panasonic PT-L780NTU projector. The Chief mount affixes to an industry standard 1.5” O.D. pole. Unfortunately, the adapter included with the amplifier tightens to 1.75-inches maximum, so I had to fashion a bushing that would allow me to snuggly hold the PA702. I interfaced the projector to activate the audio sensing circuit, thus turning on the PA702 when the class played a DVD through the system. This gave the operator one button operation, with no need to turn on and off the amplifier. The amp’s small footprint was a natural fit between the projector and the ceiling. And the recessed screwdriver adjustable volume controls kept twiddling fingers at bay.
Summary
I found that the amplifier had good sonic qualities and ample headroom to drive the four 8-inch coaxials. I would like to see an adapter that would allow the PA702 to be mounted to a typical 1 and 3/8” diameter speaker tripod; it has enough power to drive a small pair of two-way box speakers, which would make it handy for rentals. It certainly is put together solidly enough to handle rental abuse. At an affordable $332 manufacturer’s suggested retail, the PA702 is a great niche product that lends itself to a myriad of applications.
Microphones Need sound amplified or recorded? Shure microphones are the recognized leader for both stage and studio. Wireless Microphone Systems available online.
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