automotive subwoofer

Transcription

1 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 infinitebaffle 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 enclosures 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 2

3 infinite baffle An infinite-baffle system has no separate enclosure, per-se. In effect, it uses the trunk of the automobile as the enclosure. When installed properly, this system acts like a large sealed enclosure, 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 installations. 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 frequencies 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. Maximum SPL is somewhat lower than vented systems, 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. 3

4 vented Also known as ported or bass-reflex enclosures, these systems combine accurate musical reproduction 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 excellent 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 determines 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. 4 single-reflex band-pass This design can provide accurate musical reproduction 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 output goes into a vented chamber. The output is emitted entirely from this chamber into the listening environment through the vent. The resulting 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 airtight 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. Alternately, wires may be soldered directly to the terminals. Each voice coil has a nominal impedance of 4-Ohms. When using two subwoofers with two amplifier 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. 5

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 channel. This will give you a 2-Ohm load for each channel. When using a single woofer per pair of amplifier 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, controlled low-frequency performance. warnings and tips 8Ω series wiring 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 improper 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 bottom 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. 2Ω parallel wiring series / parallel wiring 6

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 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 PH FAX