Information Sheet

AtlasSound.com
3/4
©2017 Atlas Sound L.P. All rights reserved. Atlas Sound and Strategy Series are trademarks of Atlas Sound L.P. All other trademarks are the property of their respective owners. ATS002219 RevF 1/17
1601 JACK MCKAY BLVD. ENNIS, TEXAS 75119 U.S.A.
TELEPHONE: [phone]
FAX [phone]
Subwoofers and the Inverse Square Law
Even though frequencies below 200Hz are relatively omni-directional,
listeners can still "localize" the subwoofer from the volume produced. To
avoid "hot spots" it may be necessary to use two or more subwoofers
tapped at a lower setting spread throughout the room instead of a single
subwoofer tapped at maximum wattage.
Ratio of Subwoofers to Full Range Speakers
Due to the many potential variables, it is difficult to give accurate
suggestions on system design. It is important for the system designer to
look at the required SPL at ear level, ambient noise in the room, speaker
/ transformer efficiency, and transformer insertion loss to determine
the number of speakers and amplifier power required. In 70.7V / 100V
systems, care should be taken so the total speaker power taps do not
exceed the amplifier's 70.7V output capability.
The following “rule of thumb” information and examples are offered to
provide a starting point for system design.
For “good” low frequency augmentation in a full range system (all full
range speakers and FAPSUB-1 subwoofers on the same amplifier), a
single FAPSUB-1 should be used for every four full range speakers.
For “excellent” low frequency augmentation in a full range system (all
full range speakers and FAPSUB-1 subwoofers on the same amplifier), a
single FAPSUB-1 should be used for every two full range speakers.
Amplier Limitations
Even with the extreme efficiency of the FAPSUB-1 it will not overcome
the limitations of an underpowered system. Be sure to allow sufficient
headroom by using basic system design parameters in choosing an
amplifier.
Example Small Sports Bar
Square Feet 1,500
Ceiling Height 9'
Peak Ambient Noise Level 75 dB
Program Digital Music
Full Range Speakers
Eight Atlas Sound FAP42T speakers tapped at 4 watts each (32 watts
total) will provide 90dB on axis at 3.5' ear height (15dB above ambient).
13.5' spacing between speakers provides minimum overlap coverage at
4kHz.
Subwoofers
Two Atlas Sound FAPSUB-1 subwoofers tapped at 30 watts each (60
watts total) will fill out the low frequencies at 8dB above the level of the
full range speakers. If boundary loaded into one corner of the room the
level will be increased another 6dB (14dB above the full range speakers).
Total Wattage: 92 watts x 1.3 Multiplier (for headroom) = 119.6 watts
Amplifier Power Suggested: 120 Watts Atlas Sound AA120
Amplier Low Frequency Capability
Many 70.7V / 100V power amplifiers on the market today are from the
era when business music systems extending down to only 100Hz were
widely accepted. These less expensive amplifiers are not capable of
driving today's high fidelity systems that require sound below 100Hz.
When specifying the Atlas Sound FAPSUB-1, which operates well below
100Hz, it is very important to use a power amplifier capable of full
output down to and below the lowest frequency going INTO the amp,
which is often around 50Hz. An amplifier with low-frequency capability is
absolutely crucial whenever the system includes a subwoofer and is very
important for today's high fidelity business music systems.
Architect & Engineer Specications
The loudspeaker system shall be Atlas Sound FAPSUB-1 or approved
equal. System shall include a high performance 8" subwoofer
loudspeaker, ported bass reflex enclosure, and stud mount grille for
conventional ceiling installation.
Frequency response for the system shall be 45Hz – 120Hz (±10dB) and
the sensitivity shall be 89dB (SPL at 1W / 1M).
Loudspeaker shall be comprised of an 8" low frequency cone type driver.
Magnet shall be a minimum of 20oz (580g) and the voice coil diameter
shall be 1". Transformer shall be 70.7V with primary taps at 1.9, 3.8, 7.5,
15, 30, and 60 watts. A front mount tap selector switch shall be included.
This switch shall have a transformer bypass setting for 8Ω / direct
coupled operation.
Enclosure shall be a deep drawn, 937 in3, steel enclosure design. To
facilitate connection in conduit systems, enclosure shall be equipped with
an access panel covering a recessed terminal cup. This cover shall provide
a combination
3
/4" (19mm inside diameter) / 1" (25mm inside diameter)
knock-out on the side access and a top access compression fitting /
strain relief to facilitate flexible conduit up to 22mm outside diameter
or 1" (25mm inside diameter) conduit when the compression fitting is
removed.
External wiring shall be accomplished via a removable, lockable wiring
connector with screw-down terminals to provide both secure wire
termination and prewiring capability before loudspeaker installation.
The 4 pole locking Phoenix Style / Euro connector shall facilitate in / out
connections and shall be located in the recessed area behind the conduit
access panel.
Seismic support eye shall be provided on top of enclosure for additional
suspension point when used in drop tile ceilings. Construction of
enclosure shall be a minimum of 18-gauge deep drawn galvanized metal.
The system shall include a support backing plate to reinforce the ceiling
material and tile support rails for use on either 2' x 4' (609mm x 1219mm)
or 2' x 2' (609mm x 609mm) suspended ceiling tiles. This assembly can
all be installed from beneath the ceiling tile.
Overall front face diameter shall not exceed 15
3
/4" (400mm); overall depth
from the bottom of the ceiling shall not exceed 12
3
/4" (323mm). Grilles
shall be a press fit installation, manufactured 24-gauge (perforated mesh)
and finished in white epoxy.