2 Description
2.2 Unpacking
2.3 Optional
Accessories
2.4 General Description
Professional studio quality
processor
Universal interfacing
Digital signal processing
Digital signal transmission
using ACS Audio Coding
System
Digital receiver
Acoustic status indicator
914 MHz or 864 MHz
UHF headphones available
separately
Rack mount case
2.5 Four 3-D Sound
Processing Techniques
14
HEARO 999
AK 1 RCA to
AUDIOSPHERE
RCA stereo
DIGITAL
connecting
TRANSMITTER
cable
Check the packaging. If any of the above items is missing, contact your AKG dealer
immediately.
RMU 60 rack mount kit for one or two HEARO 999 AUDIOSPHERE II units
The HEARO 999 AUDIOSPHERE II is a UHF transmitter designed specifically for use with
digital wireless headphones from AKG. Outputs for hardwire stereo headphones and
loudspeakers allow the unit to be used in professional recording studios as well. The
heart of the HEARO 999 AUDIOSPHERE II is a high quality digital signal processor whose
high resolution ensures optimum sonic results with both analog and digital program
material.
The HEARO 999 AUDIOSPHERE II provides analog and digital inputs for easy interfacing
with analog outputs on audio, video, TV equipment or PCs as well as digital outputs on DVD
and CD players or digital TV sets.
Analog signals are digitized immediately after the input stage. All signal processing that
affects the sound takes place in the digital domain. This maintains the full dynamic range of
the input signal and minimizes noise.
The signal is transmitted in its digital form to the receiver in the wireless headphones.
Conventional digital audio signal transmission techniques delay the signal by about 60 to 100
milliseconds due to the required data compression. As a result, TV or video sound may seem
slightly out of sync. The ACS Audio Coding System developed by AKG is he first technique
that reduces the time delay to approximately 5 milliseconds so that there will be no notice-
able delay between picture and sound.
The receiver built into the headphones converts the received digital signal into an ana-
log audio signal. The greatest advantage of digital over analog transmission is that it
requires neither an automatic gain control (AGC) nor a compander system. This maintains the
full original dynamic range of the audio signal. Other benefits of this process include mini-
mum noise, better high-frequency reproduction, lower distortion, better interference rejec-
tion, and consistent transmission quality throughout the transmitter range of up to 165 feet
(50 m) under ideal transmission conditions (free field). Unlike infrared signals, RF signals will
penetrate walls and ceilings.
If the transmitter and receiver are tuned to different frequencies or if you are too far from the
transmitter, you will hear a beep tone in the headphones.
The HEARO AUDIOSPHERE II is available for one of two frequency bands: 914 MHz (US
and Canada) or 864 MHz (UK, Europe, etc.).
The HEARO 999 AUDIOSPHERE II system lets you share your listening enjoyment with
other persons. You can operate your transmitter with several digital headphones simultane-
ously. Make sure to use digital wireless headphones operating in the same UHF frequency
band as the HEARO 999 AUDIOSPHERE II.
The HEARO 999 AUDIOSPHERE II features a 1 U half-rack case with removable feet. The
optional RMU 60 rack mount kit allows you to install one or two units side by side in a 19"
rack.
The HEARO 999 AUDIOSPHERE II is the first device that provides four unique 3-D sound pro-
cessing techniques in one unit:
•
IVA Individual Acoustics with 7 selectable ear matching functions for absolutely realist-
ic, three-dimensional listening through headphones;
AK 2 mini
DK 1 fiber
jack to 2 x
optical cable
RCA stereo
connecting
cable
Mini to 1/4"
AC Adapter
stereo
adapter