Smart AFT660 Operating Manual
Copyright 1998 by SMART Devices Inc.
5945 Peachtree Corners East
Norcross, GA 30071-1337
Table of Contents
AFT660 AFTERBURNER
SECTION 1 INTRODUCTION .......................... 2
SECTION 2 INSTALLATION .................................... 3
SECTION 3 OPERATING INSTRUCTIONS ....... 4
SECTION 5 HOOK-UP DIAGRAMS ................. 5
SECTION 6 SCHEMATICS .................................... 10
AFT660PnP AFTERBURNER W/ DIGITAL PLUG 'N PLAY
SECTION 7 INTRODUCTION .......................... 14
SECTION 8 INSTALLATION .................................... 15
SECTION 9 OPERATING INSTRUCTIONS ....... 17
SECTION 10 SCHEMATICS ................................... 18
SMART products are designed to deliver unsurpassed quality in workmanship and performance. The
following information gives detailed instructions on the installation and operation of the SMART AFT660
processor. We strongly encourage new owners of the AFT660 to thoroughly read this entire manual before placing their new SMART product into service. This will ensure that the AFT660 will be operated
properly to give the superior performance that it was designed to deliver.
For service or installation assistance, please call our
Technical Support Department between the hours of
8 a.m-5 p.m. E.S.T., Mon.-Fri.
1-800-45-SMART
LIMITED WARRANTY: SMART products and accessories are warranted against malfunction or failure due to defects in workmanship or materials for a period of one year from the date of shipment. If a problem occurs during the
warranty period, the unit will be repaired, or replaced at our option, without charge for materials or labor. If air freight
is requested by the dealer, the difference between air and surface charges will be billed to the dealer. This limited
warranty does not cover products that have been abused, altered, modified, or operated in other than specified conditions. Prior factory approval is required on all returns. Returned equipment or defective parts must be shipped
freight prepaid to us by the dealer or customer.
Our limited warranty does not cover damages resulting from accident, misuse or abuse, lack of responsible care, or
failures not attributable to manufacturing defects, except as provided herein. SMART Devices, Inc. makes no warranties, express or implied, including warranties of merchantability or fitness for a particular purpose.
RETURN POLICY: Factory authorization MUST be obtained before returning any product. A 15% restocking charge
will be issued on unused equipment (in original box) that is returned for credit. Credit is issued to the dealers account. The credit may be used against future purchases and no cash transactions are offered. All returns must be
shipped freight prepaid by the dealer. Equipment returned without a factory RA (Return Authorization) will be refused.
AFT660 Afterburner & AFT660PnP Digital Plug 'N Play
Installation and Operation Manual
AFT660 Afterburner
For Digital Systems
Introduction
Many theatres added digital sound in order to present
the best available format, but found that their present
power amplifiers and speakers were not up to the job of
handling the increased sound levels without distortion
during the most dynamic portions of the movie. Increased dynamic capability means the sound difference
between average dialog levels and the maximum action
sequence can be extremely wide. You cannot simply
add a digital player to an existing sound system without closely studying the capability of the amplifiers and
speakers to reproduce the increased sound levels. Most
existing cinema stereo systems were designed to adequately handle the maximum levels of optical stereo.
With louder sounds created by more channels and
more dynamic range, more sound pressure is produced.
This can cause annoying “sound bleed through” to adjacent auditoriums through common air conditioning
ducts, passageways, a common ceiling and thin walls.
A common complaint from audiences about digital
sound systems is that the sound is too loud. Our hearing is most sensitive to mid-range frequencies. Louder
mid-range sounds appear to be sharp or piercing in
proportion to the bass frequencies. A skilled recording
artist can fix this in the mix by re-equalizing the track
during loud sequences to minimize the subjective harsh
sound. Unfortunately, you cannot control the content
of the soundtrack you receive. An operator who is responsible for 12 booths cannot run to a single booth
and turn it down every few minutes. Often, what happens is the sound level is set to compensate for the
loudest parts of the movie and the dialog is then hard to
hear.
The chart below shows how the sound pressure is controlled when the threshold is reached. The actual
threshold point is set by the installer in the auditorium.
Some theatres would require a lower threshold level
than others. The end result is that a normal dialog level
can be achieved consistently and the loud passages are
controlled automatically. The AFT660 is installed between the output of any digital player and the rest of
the system. Convenient plug in cables make the installation quick and easy. The product only occupies 1 3/
4” of rack space. An emergency bypass switch on the
front of the product will hard wire the digital player
around the AFT660 so that it won’t cause a failure to
the digital system.
If the system amplifiers and auditorium speakers are
not quite big enough, the AFT660 will control the
amount of power that is fed to them. A reduced sound
level means less complaints from patrons and less
sound bleed through to other auditoriums. The action
of the limiters has been carefully shaped so that you
cannot hear the product working. The resulting sound
would appear to be similar to a good optical SR print.
However, all the other sterling attributes of the digital
recording are preserved, such as extended fidelity, no
soundtrack noise and low distortion.
The Model AFT660 AFTERBURNER from SMART
solves all of these problems. The AFT660 is an automatic 6-channel threshold limiter that “burns off” the
top dynamic range of the soundtrack. Unlike simple
compressors or peak limiters, this circuit does not affect
the sound dynamics until the threshold (which is adjustable) has been reached. All louder sounds are then
reduced by a 2:1 ratio above the threshold. The AFT660
is extra sensitive to the mid-range frequencies that our
ears are most sensitive to. The stage and surround
channels track together to keep the channels balanced
whenever one of the channels reaches its threshold.
The subwoofer’s threshold level is set separately from
the other channels.
2
INSTALLATION AND OPERATION
A large button on the front of the product allows the operator to select the mode of operation. If the digital
soundtrack you receive is well recorded and well balanced, then do nothing. The signals will pass through
the AFT660 without being altered. However, if you receive a screamer, the operator can push the ENABLE
button and the automatic level control kicks in. No special training of the staff is required.
Installation
Inputs and Outputs
The output of the digital decorder should feed directly
into the input of the AFT660 for the unit to operate
properly. However, if desired, the AFT660 can be installed after the processor so that the AFT660 can monitor the levels of both optical and digital prints using the
Afterburner Breakout board (Part #0660A390). See the
Afterburner Breakout board section of the Setting the
Threshold Levels instructions.
See section 5 for configuration diagrams for various
types of systems.
If the AFT660 is installed into an existing digital sound
system, it will not effect any calibration settings that
were made previously. Only the threshold levels of the
AFT660 need to be adjusted.
The AFT660 has two inputs, both of which are connected together in parallel. One input is a female DB25
connector, and the other is a header pin connector.
Both will accept the outputs of any six channel digital
decoder. Only one input will be used and the choice
will depend on the other equipment used (see hookup
diagrams). Smart offers adapter cables to mate any
digital decoder to the AFT660. See the illustrations at
the end of the manual for specific hookup instructions.
The AFT660 has two outputs, both of which are connected together in parallel. One output is a male DB25
connector, and the other is a header pin connector.
Only one output will be used. The output from the
AFT660 will mate with the rest of the sound system. On
SMART processors, this will be the digital inputs on the
processor. See the illustrations at the end of the manual
for specific hookup instructions.
Setting The Threshold Levels
There are two threshold levels on the AFT660 that need
to be set after hooking the unit into the sound system.
One is the threshold level for the five main channels
(Left, Center, Right, Left Surround & Right Surround).
The other is the threshold level for the Subwoofer chan-
nel. The threshold level trimpots are located at the rear
of the unit. Two single-turn pots allow the user to set
the threshold level. Turning the pot clockwise increases the threshold level. In other words, a louder
sound passage is required to reach the threshold level.
Turning the pot counterclockwise has the reverse effect.
Once a sound passage exceeds the threshold level, the
AFT660 compresses the audio above the threshold level
at a 2:1 ratio. This means that for every 2 dB increase in
sound pressure level above the threshold, the AFT660
allows only a 1 dB increase. The instructions below
will outline a procedure for setting the threshold level
at what we believe is an optimum setting. However, the
end user is free to lower or raise the threshold level from
this setting to accommodate their particular situation.
DTS: The DTS digital decoder is supplied with a test
disc titled “DTS 6-track Setup Disc.” This disc is a convenient item for setting the AFT660 threshold levels.
The test disc has 50 tracks with different test signals for
the various channels. One test is “Pink Noise @ Reference Level (85 dB SPL).” The Left, Center and Right
channels have different tracks for this test:
Track #37 — Left Pink Noise @ Reference Level
(85 dB SPL)
Track #39 — Center Pink Noise @ Reference Level
(85 dB SPL)
Track #41 — Right Pink Noise @ Reference Level
(85 dB SPL)
Put the test disc in the DTS and adjust the rotary dials
for track #37. This is the Left channel pink noise test.
Make sure that the engage light on the front of the
AFT660 is on, indicating that the AFT660 is “active.” If
not, then press the Engage button to activate the
AFT660 (the light on the Engage button will illuminate).
With the Pink Noise playing, adjust the MAIN threshold control until the red LED just above the pot illuminates. Turn the rotary dials on the DTS for both Center
and Right Pink Noise (see above). Make certain that the
LED above the threshold pot illuminates while these
channels are playing Pink Noise. Make any minor adjustment to the MAIN threshold pot so that all three
tests illuminate the red LED
Adjusting Subwoofer threshold level: Set the rotary dials on the DTS to track #42. This is Sub-Bass Pink
Noise @ Reference Level (85 dB SPL). With the Pink
Noise playing, adjust the SUB threshold control until
the red LED just above the pot illuminates.
These adjustments set the AFT660 to activate its 2:1
compression when the sound pressure level in the auditorium reaches 85 dB. As stated before, the end user
may wish to set the threshold level to a higher or lower
3
AFT660 Afterburner & AFT660PnP Digital Plug 'N Play
setting depending on their requirements.
Other Digital Decoders:
If there is a pink noise source available for the system,
play it through the Left channel. Set the system so that
85 dB SPL is measured in the auditorium while the Afterburner is DISENGAGED. Engage the Afterburner,
and adjust the MAIN threshold level so that the red
LED just about the pot just comeson. Confirm that the
LED stays on when pink noise is played through Center and Right channels also.
Play the pink noise through the subwoofer channel at
85 dB SPL in the auditorium, again engage the Afterburner and set the SUB threshold level so that the red
LED just above the pot just stays on.
If no calibration sound material is available, then setting the threshold levels for other digital decoders will
require playing a digital print and setting the threshold
levels by ear. Wait for a sound passage that has some
strong dialog. Set the MAIN threshold level so that the
red LED just above the pot blinks during these passages. Verify that during loud action scenes the red
LED illuminates. For the SUB threshold adjustment,
wait for a sound passage with a strong amount of
subwoofer material. Adjust the SUB threshold level so
that the red LED above the pot just illuminates.
Using the Afterburner Breakout board:
When using the Afterburner AFTER a processor to compress optical and digital soundtracks, it is possible to
set the thresholds using either a digital OR optical Pink
Noise track, and then following the instructions in the
Other Digital Decoders section above.
cuitry in the AFT660. In the event that the AFT660 has
failed, this switch can be turned off which will force the
audio channels to be “hard bypassed” around the
AFT660.
Engage Button
This button on the front panel turns the compression
circuitry on and off in the AFT660. When the red LED
on the button is illuminated, the compression circuitry
is activated. This is the normal power-up state for the
AFT660.
Processing LED
When this LED on the front panel illuminates, the audio level coming into the AFT660 has surpassed the
threshold level, and the compression action on the high
end of the audio material is taking place. This LED
should only illuminate on hard or loud passages. If it is
never illuminating or is on all the time, then the threshold levels may not be set properly (see Installation Instructions). This LED will illuminate whenever the
Subwoofer or one of the five main channels (Left, Center, Right, Left Surround or Right Surround) exceeds the
threshold level.
Pinout Configuration
Input DB25: Input Header:
Left: Pin 1 Left: Pin 2
Center: Pin 3 Center: Pin 14
Right: Pin 5 Right: Pin 8
Left Surround: Pin 6 Left Surround: Pin 4
Right Surround: Pin 7 Right Surround: Pin 3
Subwoofer: Pin 8 Subwoofer: Pin 10
GND: Pin 14-25 GND: Pin 1
Mono: Pin 9 Mono: Pin 19
Music: Pin 10 Music: Pin 13
Stereo A: Pin 11 Stereo A: Pin 20
Digital: Pin 12 Digital: Pin 18
SR/Optical: Pin 13 SR/Optical: Pin 17
-15 VDC: Pin 11
+15 VDC: Pin 12
Note: When either of the red LED’s above the threshold
pots illuminate, the red PROCESSING LED on the front
of the AFT660 will also illuminate, indicating that the
AFT660 is compressing the top end of the sound material.
Operating Instructions
Red Bypass/Power Switch
This switch located on the front panel applies power to
the unit and routes the audio channels through the cir-
4
Output DB25: Output Header:
Left: Pin 1 Left: Pin 2
Center: Pin 3 Center: Pin 14
Right: Pin 5 Right: Pin 8
Left Surround: Pin 6 Left Surround: Pin 4
Right Surround: Pin 7 Right Surround: Pin 3
Subwoofer: Pin 8 Subwoofer: Pin 10
GND: Pin 14-25
Mono: Pin 9
Music: Pin 10
Stereo A: Pin 11
Digital: Pin 12
SR/Optical: Pin 13
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