automotive
subwoofer
2
introduction
Thank you for selecting an a/d/s/ subwoofer for your car stereo installation. Your subwoofer was
engineered and built to provide you with exceptional performance which is not only powerful, but
musical as well. Bass extension, detail, and transient response are remarkable. Narrow voice coil
gaps and suspension systems that allow long, linear throw enable these subwoofers to provide the
best performance available in their intended applications.
The A-series and 3-series are comparable in quality. Do not think of one line as the “step-up”
from the other, merely that they are optimized for different applications. The higher cost of the 3-
series is the result of the dual voice-coils and different materials used to optimize its performance
for smaller enclosures.
· The A-series subwoofers; A8s, A10s and A12s are the optimum choice for vented and bandpass
enclosures, or for infinite-baffle use. They are also a good choice for moderate to large
sealed enclosures.
· The 3-series: 308rs, 310rs and 312rs is best for small sealed and vented enclosures, or for
small single-tuned bandpass applications. The 3-series is not recommended for infinite-
baffle applications.
Both series feature rugged, cast aluminum frames. These assure precise alignment of all the parts
and also help conduct heat away from the voice-coil. All models use massive high efficiency vented
magnet structures with extended center poles for excellent linearity and high power handling.
The A-series utilize a single 4-Ohm voice coil wound with oxygen-free copper wiring and bonded
to a Kapton former with Thermoset adhesives. The 3-series feature Bifilar wound dual 4-Ohm
voice coils on anodized aluminum formers. The mineral filled injection-molded cones of the A-
series are light and rigid, guaranteeing high SPL capability without cone breakup in vented enclo-
sures or when used infinite baffle. The 3-series use anodized aluminum cones chosen for their
extreme stiffness and higher mass, making them ideal for small sealed enclosures.
getting the most from your subwoofers
As with any subwoofer, how you use it is as important as the qualities of the woofer itself. The
enclosure in which you mount the driver, is vital to it’s resulting performance. There are a variety
of different enclosure designs to choose from, each with their unique benefits and disadvantages.
Of the myriad of choices, the most common designs used in car audio are:
· Infinite Baffle - sometimes called “free-air”.
· Sealed enclosure - a.k.a. “acoustic suspension”.
· Vented enclosure - a.k.a. “bass reflex”
· Single-reflex bandpass
3
infinite baffle
An infinite-baffle system has no separate enclo-
sure, per-se. In effect, it uses the trunk of the
automobile as the enclosure. When installed prop-
erly, this system acts like a large sealed enclo-
sure, without occupying any trunk space. In
theory, the trunk is so large, that it’s effect on the
woofer’s frequency response is insignificant, and
the output is essentially the same as the driver
alone. Virtually all the sonic characteristics of
sealed systems are valid for infinite baffle instal-
lations. Installation time is typically less than other
systems because no enclosure is constructed.
Excellent performance can be achieved this way,
at the expense of maximum SPL.
This is because all of the other enclosure types help control woofer cone motion at low frequen-
cies or high output levels. In an infinite-baffle installation, the woofer’s suspension and motor
assembly are the only forces controlling the cone motion, so high signal levels are more likely to
cause woofer bottoming.
To use an A-series woofer this way, we recommend a baffle board be constructed from at least ¾”
thick MDF (medium density fiberboard). The baffle is most commonly mounted to the underside of
the rear package shelf, or behind the rear seat. It should be sealed against the vehicle structure
with gasket material, so that it is completely isolates the sound from the rear of the woofer from
the sound from the front. If there is a solid metal panel between the woofer and the vehicle
interior, it must be perforated for the sound to get through. Do not cut large areas of metal out of
the shelf since it acts as a structural support in most cars. Instead, perforate it with small diameter
holes. Some automobiles have solid metal between the trunk and the back of the rear seat which
provides adequate isolation. With other seats, especially the fold down type, another piece of
MDF should be installed as an isolation wall.
sealed
Sealed enclosures, sometimes called “acoustic
suspension” systems provide extremely accurate
musical reproduction. They are easy to construct
and provide the most consistent results. Maxi-
mum SPL is somewhat lower than vented sys-
tems, but the gradual response roll-off of these
systems works well in concert with the acoustic
loading of automobile interiors. This means that
they often provide deeper bass response in the
automotive environment than vented systems.
Acoustic suspension systems also typically provide
the best musical detail and definition.
4
vented
Also known as ported or bass-reflex enclosures,
these systems combine accurate musical reproduc-
tion with high output level capability. Physically, a
bass reflex system is merely a sealed box with the
addition of a tuned vent. They can produce excel-
lent sound when properly constructed but are
slightly more difficult to build than a sealed box.
One myth of vented enclosures is that they are more
“efficient” than a sealed enclosure, implying that
they will play louder with less power. This is not
necessarily true, the sensitivity of the woofer de-
termines the SPL output for a given power input to
that woofer. Since this is a characteristic of the
woofer, not the enclosure, it will have the same
sensitivity in both sealed and vented enclosures. The
SPL advantage of the vented enclosure comes from
the fact that the effect of the vent tuning reduces the excursion of the woofer cone near the
tuning frequency, allowing more SPL to be produced before the cone “bottoms”.
Tuning bass reflex systems correctly “in the field” can be tricky. Without proper test equipment
there is a high possibility of error when trying to tune these systems. There are a number of
excellent software packages available to help you design an optimum enclosure. If you do not
have access to such software, follow the enclosure and vent dimension recommendations on the
specification sheet included with your subwoofer.
single-reflex band-pass
This design can provide accurate musical repro-
duction with high SPL capability and reduced
mid-bass distortion. This is a combination of the
sealed and vented designs. In a single reflex
bandpass system the rear of the woofer is loaded
into a sealed enclosure, the woofer’s front out-
put goes into a vented chamber. The output is
emitted entirely from this chamber into the lis-
tening environment through the vent. The re-
sulting system is essentially a sealed enclosure
with an additional acoustic low-pass filter formed
by the addition of the vented chamber. Single
reflex bandpass systems offer some advantages.
They are often easier to install because only the
vent must exit to the passenger compartment,
not the woofer. In addition they can be “tuned”
to provide the desired performance characteristics. Unlike sealed or vented systems, you can
effectively increase the system’s apparent sensitivity with appropriate tuning choices. You can
choose to design a for a narrow frequency band, with very high sensitivity, or you can trade-off
some sensitivity for a wider bandwidth. The damping effect of the vented chamber reduces the
motion of the cone compared to a sealed enclosure thereby allowing potentially higher sound
output without the woofer reaching mechanical limits.
As with vented systems, proper construction and tuning is critical to good performance. Minor
deviations from the ideal design may cause frequency response or distortion problems. Follow the
enclosure design recommendations closely, or use one of the respected software packages.
5
construction
materials and assembly
Regardless of the type of enclosure design you choose, it must be solidly constructed and be free
of any air leaks. Make the panels from MDF or Baltic birch plywood at least ¾” (20mm) thick. All
joints should be liberally glued with carpenter’s glue or construction adhesive. Do not depend on
hot-glue, or screws, for joint strength. If screws or staples are used, use them only to hold the
panels in place while the glue dries.
It is a myth that vented enclosures do not need to be as airtight as sealed enclosures. Due to the
reactive effect of the tuning, the internal pressures at some frequencies are greater in vented or
bandpass enclosures than in sealed enclosures. Make a point to make all enclosure types as air-
tight as possible.
Fiber-reinforced resin may also be used to form difficult shapes. When designing an enclosure this
way, try to avoid large flat panels which may easily flex and rattle under pressure.
The woofer should be sealed to the enclosure with foam gasket material or RTV silicone.
damping material
The internal walls of a vented enclosure, or the vented side of a bandpass enclosure, should be
lined with acoustic damping material in order to reduce sonic reflections. If you are constructing a
wood enclosure without any see-through sides, common polyester fiberfill batting or fiberglass,
approximately 1” thick, is good for this purpose. There are a number of commercially available
damping materials available if you need something cosmetically suitable for use in an enclosure
with see-through sides. A sealed enclosure, or the sealed portion of a bandpass enclosure, should
be completely filled with fiberglass or polyester fiberfill with a density of approximately 16oz. of
material for each 1 cu.ft. of enclosure volume. If you choose to use a sealed enclosure without
damping material, add 20% to the enclosure volume recommended on the specification sheet.
vents
Although the vent specifications in the enclosure recommendations are round, they may be any
shape which lends itself to your installation. To adjust vent dimensions from those we recommend,
maintain the same ratio of vent area to vent length. Be careful when you consider changes
however. If you increase vent area, the length must increase to maintain the same ratio. This may
make the vent unreasonably long. If you decrease vent length, the area will need to be decreased,
possibly resulting in excessive wind noise from the vent. To keep vent noise to a minimum, radius
all of the sharp edges of the vent.
wiring
A-series
Each of the terminals used on the speakers is marked on the fiber panel adjacent to the terminal
indicating it’s polarity. These terminals accept standard .250” female quick-disconnects. Alter-
nately, wires may be soldered directly to the terminals.
Each voice coil has a nominal impedance of 4-Ohms. When using two subwoofers with two ampli-
fier channels, it is best to wire each woofer to an individual channel. When using more than one
woofer per channel, they may be wired in series or parallel, as shown on the next page, depending
on the impedance drive capabilities of your amplifier.
6
3-series
The binding posts used on these models are color
coded to indicate polarity. Red is (+), and Black is (-
). These binding posts will accept bare wire, spade
lugs, or banana plugs.
Each of the 3-series woofers has dual 4-Ohm voice
coils. These may be used individually on separate
amplifier channels, or they may be wired in series
or parallel. Connecting both voice coils of a single
woofer in parallel creates the equivalent of a single
2-Ohm woofer. Connecting the two voice coils in
series will create the equivalent of a single 8-Ohm
woofer. When using a pair of woofers on a pair of
unbridged amplifier channels it is best to parallel
the two voice coils of each woofer, and connect
each woofer to it’s own dedicated amplifier chan-
nel. This will give you a 2-Ohm load for each chan-
nel. When using a single woofer per pair of ampli-
fier channels, connect each voice coil to it’s own
channel instead of bridging the channels as you
would for a single voice coil woofer. This will result
in the best damping factor and assure tight, con-
trolled low-frequency performance.
warnings and tips
installation
An unsupported subwoofer enclosure can be a deadly projectile in the event of an accident or
sudden stop. It is up to you to make sure that the subwoofer enclosure is firmly mounted to the
vehicle.
power handling
Your a/d/s/ subwoofer has been designed to handle the demands of high power, high energy
music reproduction. Despite their rugged construction, it is still possible to damage your speakers
if they are used improperly. An inappropriately designed or constructed enclosure can allow im-
proper cone motion, possibly causing physical damage to the voice-coil or suspension. Excessive
drive power for extended periods can cause thermal damage to the voice coil or lead-in wires. Too
much low frequency energy may cause the woofer cone to reach it’s mechanical limits and “bot-
tom” against the structure. In general, you will hear distortion as a warning before any damage
occurs. If you hear distortion, immediately reduce the drive level to the point where the sound
retains it’s clarity. This will assure that you do not damage your woofers.
sound pressure level
Extended listening at high signal levels has been proven to cause permanent hearing damage. a/
d/s/ loudspeakers used with high power amplification are capable of reaching such levels in certain
system configurations. When using a/d/s/ loudspeakers with high power amplification, make sure
to listen responsibly. If you are listening at high volume be sure to use hearing protection, or reduce
the volume to safe levels.
8Ω
4Ω
4Ω
+
–
+
–
series wiring
2Ω
4Ω
4Ω
+
–
+
–
parallel wiring
4Ω
4Ω
4Ω
+
–
+
–
4Ω
+
–
series / parallel wiring
4Ω
+
–
7
warranty information
There are two things you must do to ensure trouble free service in the event you need warranty repairs.
1 - Keep your original sales receipt in a safe place. A copy of the receipt will be required to obtain warranty service.
2 - Be sure your retail dealer has written the date, the model number, and the serial number (if applicable) of the Product on the
receipt.
To give yourself an extra measure of protection, make a separate record of the information about your purchase and keep it in
a safe place. In the event you misplace the sales receipt, your dealer may be able to give you a copy.
Take a moment now to read the terms of your warranty. Check to be sure your sales receipt is dated and has the Product model
number and serial number (if applicable) on it. Then put it away in a safe place.
When shipping a Product in for service:
• Enclose a copy of your original sales receipt that has the date, the Product model number and serial number (if applicable)
written on it.
• Always ship Products in the complete original packing material.
• Avoid shipping Products via the Postal service. If you must use the Postal service, be sure to register and insure the package.
a/d/s/ Limited Warranty
Analog and Digital Systems, Inc. (a/d/s/) warrants to the original consumer purchaser of the a/d/s/ Products described in this
manual, that the Product will be free from defects in materials and workmanship for a period of one (1) year after the date of
purchase. If the product is installed by an authorized a/d/s/ retail dealer, the warranty is extended to three (3) years, a/d/s/' sole
obligation under this warranty shall be to provide, without charge, parts and labor necessary to remedy the defects, if any, that
appear during the warranty period.
This warranty is the sole and exclusive express warranty given with respect to the Product. All other express warranties are hereby
excluded. Neither a/d/s/ nor the authorized dealer who sells the Product is responsible for indirect, incidental, or consequential
damages. Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above limitation
or exclusion may not apply to you. This warranty gives you specific legal rights and you may also have other rights which vary
from state to state.
IMPORTANT - Keep your original sales receipt. Be sure the retail dealer has written on it the date, model number, and serial
number (if applicable) of the Product. This information is required for warranty service.
This warranty is limited to:
• Products purchased from authorized a/d/s/ retail dealers in the United States. a/d/s/ will supply a list of authorized dealers on
request.
In order to obtain warranty service you must:
• Return the Product, freight prepaid, to the a/d/s/ dealer from which it was purchased, an authorized a/d/s/ independent
service agency, or to a/d/s/. If necessary you may call a/d/s/ Customer Service Department for the names and addresses of
authorized independent service agencies in your area.
• Provide proof of purchase in the form of a copy of your original sales receipt. The date, model number, and serial number (if
applicable) of the Product must be written on the sales receipt.
This warranty does not cover:
• Damage that is the result of misuse, abuse, accident (including but not limited to damage by water), faulty hookup, defective
or maladjusted associated equipment, or the use of the Product with equipment for which it was not intended.
• Cosmetic defects that appear more than thirty (30) days after the date of purchase. Cosmetic damage caused by improper
handling is also excluded.
• Products that are used for commercial purposes.
• The cost of removing or reinstalling the Product.
• Damage that occurs while the Product is being shipped to whoever will service it. See the information above regarding
shipping procedures.
This warranty is void if:
• The Product identification or serial number label is removed or defaced in any way.
• The Product is serviced or repaired by any one other than a/d/s/ or an authorized a/d/s/ dealer or service agency.
analog and digital systems
one progress way
wilmington, ma 01887
usa
If you want to consult the factory, write or call our customer service department:
Customer Service Department
Analog and Digital Systems, Inc
One Progress Way
Wilmington, MA 01887
PH 978.658.5100
FAX 978.658.8498
/