Comments

"Shotgun mics do their job well. They can reach five feet across a film set and reject moderate ambience to enhance an actor's conversational voice, all with full-range fidelity. Parabolic mics do their job well too. They can reach 150 feet across an American football field and isolate the cracks of helmets from the screaming fans, with all the purposeful bandwidth of a carbon telephone handset. The problem is that there is a huge gap that needs to be filled between these two jobs".

"When the AT-89 is used, because of its full-range and narrow low-frequency pattern, the home audience will discover that there are thuds and whomps when games are played. At the other extreme, consider another televised sporting event, such as rowing. A microphone is needed to pick up the subtle rumble of the oars against the locks, the ripples in the water and the voice of the Coxswain, while rejecting the motor noise of the camera chase boat".

New Directions In Design

"AT-89 is unique in the way it accomplishes an astonishing amount of rejection of sound coming from unwanted directions. While the system does incorporate a conventional ported interference tube element, that's where tradition ends".

"Surrounding the base of this shotgun element is an interesting array of four cardioids condenser capsules dedicated to picking up the sounds you don't want to hear.
The sound from all of these elements is fed into a small, belt pack sized DSP (Digital Signal Processor), and if the cardioids array hears sounds that the shotgun doesn't hear, and/or sounds that the shotgun does hear, then those sounds are digitally suppressed from the output".

"The DSP is also aware of the tendencies for the shotgun element to be less selective with low frequencies, and it compensates for this. The end result is a microphone with up to a remarkable 80dB of off-axis rejection at 1kHz, and has directional characteristics that are actually narrower in the lower end than the high end".

"To add to the mic's versatility, the DSP box has a switch for selecting three pattern options: tight, extremely tight, and 'blade' (my term, not AT's). When the blade pattern is selected, two of the cardioids elements are disabled so that the pattern can be horizontally wide from left to right while remaining razor thin from top to bottom. Rotate the mic 90 degrees to make the pattern vertical. I imagine this pattern could allow the AT-89 to be permanently mounted overhead to cover, for instance, a hockey arena while still minimizing the crowd noise".

Field Trials

"In rodeo events, most of the action sounds are low-frequency thuds and snorts, with the occasional clanging of the gate, and voices. Parabolic's proved unsuitable for several reasons, such as being too large, and having to be held by someone out of danger from the bulls and broncos, and parabolics don't do well with the sounds that bulls and cowboys make. We had also tried mounting standard shotgun mics onto the camera lenses, but the rejection was not enough to overcome the crowd noise and PA system.
Since shotguns become more and more omni around the low frequencies, they are of little use in isolating the important thumps and bumps. When the only options were either shotguns or parabolas, all we could do was concede that we cannot fight the laws of physics and shrug our shoulders."

"When used at the rodeo, he AT-89 was awesome. The results were unbelievable.
Distinct sound effects including speech, fence noise, leather saddle noise, the thud of the cowboy hitting the dirt, even rope noise, were all easily discernable and intelligible at distances of over 250 feet! That's right, the AT-89 was mounted to the lens of a camera positioned 250 feet from the action. The sounds weren't parabolic thin either, but fat and crisp, even overcoming the sound of the crowd and PA announcer. During a subsequent rodeo event, I suggested that we mounted t the AT-89 onto a closer camera, a mere 75 feet away".

"Used for a different broadcast sporting event, 'Sculling' (rowing a thin boat), the challenges are somewhat different. When televised, these boats are chased by a small powered boat containing the camera and sound crew.
There is not the frantic crowd noise of stadium events to overcome, but the distance can be a formidable 200 feet or more, and the sounds are of much lower level and more delicate in nature. Trying to pick up these sounds while avoiding the noisy motor of the chase boat had previously been impossible when using conventional shotgun mics. The AT-89 met this challenge wonderfully. I understand that it sounded like being only a few feet away from the boats, with no detectable motor noise from the chase boat".

"I'm sure that after reading this far, the gears in heads of news producers are already spinning, dreaming about what they could do from a distance of more than 250 feet. Being able to grab distinct, full-sounding for news sound, finally being able to match the camera's zoom lens".

Signal Uses

"This microphone is bound to peak the skeptical interest of location sound mixers for film and television production, but their criteria for quality will be stricter than the sports production recording of distant sound effects. They will, and have asked, how it sounds compared to the standard top-shelf shotgun mics. All of this range and rejection comes at a price".

"With a maximum SPL of 117dB and a noise spec of 24dB, yielding a dynamic range of 93dB, the AT-89 would certainly not be the preferred choice when distance and ambience are controlled and in the 'normal' range. However, don't be misled by these specs, because when used at great distances, the SPL would rarely exceed 117dB, and the ambient level that makes this microphone necessary in the first place would certainly mask the self-noise".

"For film production dialogue, I believe the microphone could be very useful in wide crowd scenes, for instance, when needing to focus on a particular area, and in action scenes when competing with the special effects noises of wind machines, and so on".

Physical Description

"The AT-89 is actually a little shorter than most long shotguns, with a length of 14 inches.
Because of the four-element array, it takes on a modified cone shape with a maximum diameter of two-and-three-quarter inches. However, the larger diameter is in no way a detriment, because its special zeppelin windscreen is still the same diameter used by the standard shotguns.
The biggest difference is in the weight, which is a bit more than most long shotguns at one pound. However, the weight is not unmanageable on poles of 12 feet or less.
The DSP control box can be clipped to a belt and is powered internally by three 9V cells, or externally with 12V on its standard four-pin male XLR. With a current of 250mA, internal battery life is about five hours using alkaline or 12 hours using lithium".

Conclusion

"I can easily imagine an instant acceptance by sports production trucks, news production outside broadcasts and government security areas such as prisons, etc. This microphone is truly a unique and useful tool".

AT-89 Remote Kit includes:

• AT-89MIC Adaptive-array Microphone
• AT-89CP Control Pack with attached belt clip
• AT-89BH Click-on Battery Housing
• AT-89PG Pistol-grip shock mount
• AT-89Z Zeppelin-type windscreen
• AT-89C-10 Special 6-conductor shielded Cable, 10' long
• AT-89CC Carrying Case

AT-89 Specifications: