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Before final design, wood cutting, and assembly of the enclosure some basic box construction issues need to be
understood.  These items are acoustically related, some are construction tips, and some are simply to ensure a long lasting
product for the listener.  

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Infinite baffles are simply a piece of wood holding up the woofer to the back deck of a car.  If you chose this installation 
(which is generally a poor performer) you must take great care in sealing/caulking all holes that vent into the back seat for 
proper bass response.

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Wedge shaped boxes are simply a triangular box added to a rectangular box.  

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Mathematically add up the volumes of these two boxes and you have the total of a wedge shaped box.

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When making the calculations, be sure to adjust interior box volumes for port volumes and woofer displacement volumes.  

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All calculations should be made in advanced of cutting wood out.  If the final box is off by +/- 5% of optimum values don’t
worry about it; you will rarely be able to hear the difference!  This is very important since prefabricated boxes often work 
well even if off a little bit.  Also, if you do forget to compensate for woofer and port tube volume displacement, it is rarely 
acoustically noticed by most people.

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Very low frequencies simply do not care about the shape of the box.  Such wavelengths allow for nearly any reasonable 
shape or length but really odd shapes should be avoided so they can be easily cut and glued.

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Particle board, MDF, or high grade birch plywood are good materials to build boxes with thicknesses of 5/8"-1" (14-
25mm).  Solid wood panels should actually be avoided of splitting and warping over time in the car environment.

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All seams in the box should be glued, screwed, then caulked to prevent panel separation and air leaks over time.

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Cross bracing of panels is important for large boxes to prevent the panels them selves from radiating sound.

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Acoustical damping material (e.g., fiberglass batting material 2-4" thick) should cover about 50% of the interior walls.  This
helps reduce high frequency resonances and increase the box volume as seen by the woofer by about 10-15%.  

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Spraying the interior walls of the box with a damping material such as tar based automotive undercoating is one of the 
best things to help dampen wall resonances.

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The final box should allow for servicing the woofer at a later time should it be damaged for any reason.

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5-way binding posts mounted on the box for electrical connections are highly recommended.  It is then easy to remove 

the box from the vehicle for service or theft protection.

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Where possible, use the largest diameter port tubes to prevent wind noise.  PVC plumbing pipe is inexpensive and is 
common in 3, 4, and 5" diameters.  PVC “elbow” connectors allow you to make turns inside the box with the average 
diameter being along the centerline of the tube.

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Try to always use active (electronic) crossovers.  Today, most power amps have them built in. The mounting distance from
the side of the woofer and the port should be less than 12" or so if possible.  Regarding simple vented boxes, you 
CANNOT achieve lower frequency response by simply lowering the port tuning frequency from its recommended value.  
This severely over-damps the box and results in a very “muddy” sound for the box.

Before gluing and screwing everything together, lightly “tack nail” the sides together and make sure the box fits in the
vehicle.  Also, look carefully to see if the woofer magnet has enough depth of clearance from the back wall.  There are many
other things to think about when design and building subwoofer boxes but they are too numerous to mention here.  But, for
those interested, please refer to some of the related reading for more information on speakers and audio in general.

F

INAL

S

UBWOOFER

E

NCLOSURE

C

ONSTRUCTION

The following is a list of materials and sources of recommended reading for the person interested in loudspeakers,
acoustics, and audio in general.  Subjective comments are noted for each.

■

DESIGNING, BUILDING, AND TESTING YOUR OWN SPEAKER SYSTEM, David Weems, Copyright 1984, TAB Books 
#1964, Blue Ridge Summit, PA 17294.  

(This is an excellent introductory book on designing speakers for the home but is

quite applicable to the car since many concepts are carried over.)

■

LOUDSPEAKER DESIGN COOKBOOK, Vance Dickason, copyright 1991-1996, distributed by Old Colony Sound Lab, 
Peterborough, NH, 03458.  (A significant technical step up from Weems addressing complex woofer box and crossover 
designs. Clearly a reference book useful for all.)

■

BLAUBOX WOOFER BOX DESIGN COMPUTER PROGRAM, Thomas Breithaupt, Blaupunkt div. Robert Bosch 
Corporation, 2800 S. 25th Avenue, Broadview, IL 60153.  (

This is a simple to use IBM PC computer program used to 

predict the frequency response of a subwoofer in 10 different enclosures including sealed, vented, and bandpass 
configurations.  Basic passive crossover designs are covered as well.  It is provided free of charge as a download from 
the Blaupunkt Internet site at: http://www.blaupunkt.com.)

A

DDITIONAL

R

EFERENCE

I

NFORMATION

– 

9

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Содержание Blau PCwg100

Страница 1: ... VE ER R P R O COMP DRIVER PCwg100 PCwg120 Professional Quality Component Subwoofers Subwoofers à composant de qualité professionnelle Subwoofers con componente de calidad profesional Subwoofers com componente de qualidade profissional ...

Страница 2: ...Purchase Date Retailer Address City State Zip Telephone Installer Vehicle PURCHASE INFORMATION OTHER NOTES ...

Страница 3: ...focus on our new subwoofers is the vacuum formed polypropylene cone material offering lighter mass compared to older paper cones but without the flexing properties common to paper This gives a much tighter bass response without distortions often found at high listening levels Below is a good summary comparing old cones with the new technologies In addition to the vacuum formed poly cones is the ex...

Страница 4: ... and speaker wires are routed away from high current power lines for audio amplifiers and vehicle systems lines when possible This will help prevent noises from creeping into the audio system plus prevent potential damage to the vehicle wiring itself BE CARFUL WITH ALL CONNECTIONS When making connections make sure each connection is clean and properly secured Observe all polarity markings carefull...

Страница 5: ...ividing network must be installed that keeps the low frequencies out of the midrange speakers Such a crossover network directs the higher and lower frequencies to their respective drivers Such a crossover can be passive simple coils and capacitors that limit the operating frequencies seen by their respective speakers A crossover can also be active where an electronic box must be installed in front...

Страница 6: ...nse and smooth low frequency roll off Disadvantages moderate to large box sizes moderate efficiency moderate sound pressure levels VENTED BOX a k a Ported Box and Bass Reflex is simply a sealed box but with a specifically tuned tube inserted It extends the low frequency response compared to a sealed box Advantages low cut off frequency low distortion in its operating pass band excellent efficiency...

Страница 7: ...to its small size and better frequency contouring But it must be placed in front of the amplifier and process the signals via the RCA cables This is rarely a problem in most installations The passive design is more of a brute force process requiring large inductors and capacitors but it is often a cheap and dirty way to get bass response into the car quickly and without noise problems sometimes as...

Страница 8: ... by improper installation on uneven surfaces This can occur when surfaces are heavily padded or carpeted and the screws are unevenly tightened or over tightened The results will be a damaged voice coil assembly due to knocking it off center When installing more than one speaker per amplifier channel be sure that the combined impedance values will not damage the amplifier should they be too low i e...

Страница 9: ...asured in cubic inches in3 Such calculations depend upon height width and depth calculations for rectangular shapes and a diameter and height for a tube shape AREA AND VOLUME CONVERSIONS Technical data for speakers are often given in English and Metric unit values e g inches and meters Also when calculating dimensions we must often flip between size formats e g cubic inches and cubic feet To easil...

Страница 10: ...ounted on the box for electrical connections are highly recommended It is then easy to remove the box from the vehicle for service or theft protection Where possible use the largest diameter port tubes to prevent wind noise PVC plumbing pipe is inexpensive and is common in 3 4 and 5 diameters PVC elbow connectors allow you to make turns inside the box with the average diameter being along the cent...

Страница 11: ...writing by an officer of Robert Bosch Corporation THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES OR REPRESENTATIONS EXPRESS OR IMPLIED INCLUDING ANY WARRANTY IMPLIED BY LAW WHETHER FOR MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR OTHERWISE AND SHALL BE EFFECTIVE ONLY FOR THE PERIOD THAT THIS EXPRESS WARRANTY IS EFFECTIVE In the event any provision or any part or portion of this warrant...

Страница 12: ...tion DC resistance Re 3 56 ohms Force factor BL 10 2 Tm Effective cone area Sd 320 sq cm Compliance Cms 540 uM N Moving mass Mms 61 g COMMON BOX DESIGNS SEALED BOX VOLUME cu ft COMMENTS Small box 0 5 Not a lot of deep bass but O K for most listeners Pounder 1 0 O K low end but tons of power handling JAM ON IT Most accurate 1 5 Very natural low frequency performance with good transient response VEN...

Страница 13: ... Freq Freq Port tube length for 3 I D port Port tune freq Sealed rear box volume Vented front box volume Port tube length for 4 I D port cu ft Hz Hz Hz cu ft cu ft in in dB 0 75 52 140 85 0 4 0 35 4 4 8 8 90 1 00 45 130 75 0 5 0 5 4 6 9 1 90 1 25 45 110 70 0 6 0 65 4 3 8 6 90 1 50 43 95 65 0 7 0 8 4 2 8 5 89 1 75 38 92 60 0 7 1 05 5 3 10 4 88 2 00 32 95 55 0 7 1 3 6 7 13 0 87 VENTED BOX VT f3 fB P...

Страница 14: ...tion DC resistance Re 3 47 ohms Force factor BL 10 3 Tm Effective cone area Sd 500 sq cm Compliance Cms 340 uM N Moving mass Mms 84 g COMMON BOX DESIGNS SEALED BOX VOLUME cu ft COMMENTS Small box 0 75 Not a lot of deep bass but O K for most listeners Pounder 1 5 O K low end but tons of power handling JAM ON IT Most accurate 2 0 Very natural low frequency performance with good transient response VE...

Страница 15: ...rt tube length for 4 I D port cu ft Hz Hz Hz cu ft cu ft in in dB 0 75 78 180 120 0 5 0 25 0 75 1 75 93 1 00 55 150 90 0 6 0 4 1 7 4 0 92 1 25 45 130 75 0 8 0 7 2 0 4 5 91 1 50 40 120 65 1 1 0 9 2 0 4 3 90 2 50 35 95 60 1 25 1 25 2 0 4 5 90 3 50 25 85 47 1 25 2 25 4 6 9 3 87 VENTED BOX VT f3 fB PL PL SPL Total box volume Freq Port tune freq cu ft Hz Hz in in dB 0 50 62 40 9 1 NR 92 0 75 55 40 5 6 ...

Страница 16: ...erform well All dimensions are stated for exterior sizes and are calculated with compensations for box wall thickness using 3 4 wood Also each volume is adjusted for air volume displacements for a woofer average 0 15 cu ft for 10 12 woofer and a mid size port 3 dia x 7 long Please be aware of the small impact that box size fluctuations has on the end sound quality loudspeaker enclosure interior si...

Страница 17: ...n the same cabinet 4 How many ports do you have or want Diameter and length in inches of each Diameter Length 5 Do you want round or square ports or another style 6 What is the grand total cubic volume of the box you want 7 What mounting dimensions in inches are you limited to Height Width Depth 8 How much amplifier power watts rms are you applying to each woofer 9 Is there any other information w...

Страница 18: ...S 25th Avenue Broadview Illinois 60153 U S A http www blaupunkt com Copyright 1998 by the Robert Bosch Corporation No portion of this work may be reproduced in any form without the written consent of the Robert Bosch Corporation Printed in China 7 98 2nd Edition ...

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