Professional Quality Component Subwoofers
Subwoofers ti composant de
qualitci!
professionneile
-woofers-cotxomponente-de-catidad
profesiona----
Subwoofers corn componente de qualidade profissional
Made in the U.S.A
Bosch Group
TOPICS
New Pro Component features
System design guidelines
Acitve & Passive electrical configurations
Subwoofer enclosure types
Subwoofer enclosure construction
Installation guidelines
Additional reference information
Limited warranty information
Technical support
PC85 technical specifications and recommended box designs
PC1 05 technical specifications and recommended box designs
PC1 25 technical specifications and recommended box designs
PC1 55 technical specifications and recommended box designs
Blaupunkt technical support summary sheet (fax sheet)
Other notes
PAGES
1
2
3,4
4,5
6,7
8
8
9
9
28,29
30,31
32,33
34,35
36
37
Principes de conception du
systeme
Configurations
Blectriques actives
et passives
Types d’enceintes de subwoofer
Construction d’enceintes de subwoofer
Principes d’installation du
systeme
References
Garantie
limitee
Soutien technique
PC85 specifications techniques et conception recommandee des enceintes
PC1 05 specifications techniques et conception recommandee des enceintes
PC1 25 specifications techniques et conception recommandee des enceintes
PC1 55 specifications techniques et conception recommandee des enceintes
Blaupunkt demande de soutien technique
(feuille
de fax)
SUJETS
Caracteristiques des nouveaux composants Pro
PAGE
10
11
12,13
13,14
15,16
17
17
18
18
28,29
30,31
32‘33
34,35
36
Autres notes
37
TEMAS
Nuevas Caracteristicas Pro Component
Principios de
diseiio
del sistema
Configurations electricas activas y pasivas
Tipos de
caja
del altavoz
para
bajas frecuencias
Construccidn de la
caja
del altavoz
para
bajas frecuencias
Principios de
instalaci6n
del sistema
Information de referencia adicional
lnformacidn de la garantia
limitada
Apoyo
Tdcnico
PC85 especificaciones tecnicas y
disefios
recomendados de
la.caja
PC105 especificaciones
tecnicas y diserios
recomendados de la
caja
PC1 25 especificaciones
tecnicas y disetios
recomendados de la
caja
PC1
55 especificaciones
tecnicas y
diseiios recomendados de la
caja
Blaupunkt hoja de resumen de apoyo
t6cnico (hoja
fax)
Otras
notas
.
PAGINAS
19
20
21,22
22,23
24.25
26
26
27
27
28,29
30,31
32.33
34,35
36
37
_i_
subwoofersinorder to
introduce the second generation of PC subwoofers offering
unparalleled value in the car audio market. Why mess up a good design? Well, the PC
performance standards, rugged design, and flexible installation were maintained but now
offer aggressive new cosmetics and an improved owner’s manual.
Throughout the life of the PC woofers we have continued to improve the reliability to
industry leading standards in quality. We have followed product improvements with
owner’s manual refinements to help the end user in the box decision process. A COMMON
BOX DESIGN CHART offering suggested box designs for SMALLEST, MOST ACCURATE,
and POUNDER designs is given for each woofer.
This manual is composed of several sections and offers brief discussions in each area.
New PRO COMPONENT FEATURES lists technical advancements of the VPC woofers.
SYSTEM DESIGN GUIDELINES addresses system layout, sound quality, and amplifiers.
SUBWOOFER ENCLOSURE TYPES discusses the trade-offs of popular box designs with
SUBWOOFER ENCLOSURE CONSTRUCTION reviewing basic box building techniques.
INSTALLATION GUIDELINES examines additional automotive installation concerns and
ADDITIONAL REFERENCE INFORMATION offers additional technical references for those
trying to learn more about car audio. BLAUPUNKT WARRANTY INFORMATION for the
applicable country is noted. BLAUPUNKT TECHNICAL SUPPORT provides telephone and
fax support numbers and addresses with the BLAUPUNKT TECHNICAL SUPPORT
SUMMARY SHEET formalizes your tech requests so they can be mailed in and/or faxed in to
our technical support people. Finally, in-depth TECHNICAL DATA for all PC woofers is
provided.
High performance car audio can be achieved with value conscious components. Simply
speaking, 95% of the car audio subwoofer installations made today really don’t need $400
woofers with 100 oz magnets! The VPC series woofers were designed for HIGH POWER
HANDLING LEVELS, HIGH SOUND PRESSURE LEVELS, and FLEXIBLE INSTALLATION
CHOICES.
HIGH POWER HANDLING was achieved
through a new ultra-linear long-throw
suspension with “bottomless” back plate
design allowing for tremendous cone
excursion without voice coil damage. The
new rigid spider design
(Blaupunkt
trademarked as “SPIDERMAX”) renders
-
DUSTCAP
spider tears a thing of the past. Double
thickness compressed foam surrounds offer
linear cone movement without tearing from
over-excursion. New Strontium Ferrite
magnets yield smaller magnet sizes without
reduced magnet strength but retain their
magnetic power far beyond the expected
life of the woofer. Four layers of wire on
DuPont Kapton Polyamide voice coil
bobbins with “Armorcoat” allow for voice coil temperatures exceeding nearly
400”
Fahrenheit without damage. New basket designs prevent the back of the cone from
slapping the steel frame thus avoiding acoustical distortions and possible cone damage.
Rear vented pole plates allow fresh air to move in from behind the woofer to cool the voice
coil plus help prevent dust cap “popping” at the excursion limits.
-l-
SUPERIOR PERFORMANCE PARAMETERS for the new PC units were strategically balanced
so that low resonant frequencies could be achieved along with high sound pressure levels.
Cone mass is held to a minimum for high efficiency yet its Acrylic Resin Laminate (ARL)
design yields tremendous rigidity. The lighter the cone the easier it is for the magnet to
move it in and out; therefore, higher sound pressure levels for a given amount of amplifier
power input. Additional loudness is achieved through longer cone travel so we designed
the PC units with 0.25 to 0.35 inches (6-8 mm) of peak-to-peak excursion which is rarely
found in component woofers of this price range.
INCREDIBLY FLEXIBLE INSTALLATION is the real benefit to the new Pro Components. The
PC woofers perform well in sealed, vented, and
bandpass
boxes. Due to the low resonance
values, they also work quite well in infinite baffle installations where the woofer is mounted
on the rear deck of a car and uses the trunk for its enclosure.
The best investment in system design is planning time. Before building a house an architect
completely draws building plans. Although small modifications are often made throughout
construction, 99% of the home is built as planned.
Exactly the same attitude must be
followed in the design of a car audio system and we therefore refer to it as “System
Architecture”.
MULTI-WAY SYSTEMS
Although a simple head-unit with four
speakers will provide reasonable sound, a
really good system almost always requires
some kind of subwoofer. In order to
include the subwoofer speakers a dividing
network must be installed that keeps the
low frequencies out of the midrange
speakers.
“Two-way”
”
crossovers” have a
crossover point set of 80 to 100 Hz for
example. You can’go crazy with additional
crossover points and amplifiers (three-way,
five-way, etc.) but these should be left to
the better retail installers or high-end
hobbyists.
SUBWOOFER
SOUND QUALITY VS. SPL
A well designed sound system can provide good sound quality and still play loud. Above
about 120 dB (decibels) the sound isn’t perceived as getting much louder due to the non-
linearities of the human ear. A loudspeaker with reference value of 90 dB 1 watt/l meter
will usually offer about 11 O-l 15 dB inside a car if driven by an amplifier of about 100 watts
(more than enough for most listeners).
Good sound quality is achieved when a system offers several sonic attributes. IMAGING is
the accurate rendition of instrument placement which can only be achieved with proper
loudspeaker placement. STAGING is an extension of imaging where a perceived listening
event is recreated with well defined height, width, and depth as with an actual sound
stage. Correct FREQUENCY RESPONSE implies that all frequencies within the range of
human hearing (20-20 kHz) are audible and balanced in relation to one another. TIMBRE
(pronounced
Tam-bur’)
is the system’s ability to reproduce the sound signature of a trumpet
so that it doesn’t sound like a trombone. LINEARITY is the systems ability to provide
consistent frequency response regardless of volume setting. Some systems sound “shrill”
at high levels if the
tweetersgre
over driven. They may also sound weak at low volumes
due to our psychoacoustic hearing effects which we perceive bass loss at low levels.
-2-
SYSTEM PLANNING
: i I!:::,
: : I!
If,
::_
The largest possible impact on any audio
system (home or car) is the quality of
loudspeakers used and their placement.
EFFICIENCY defines how loud a speaker
will play for a given input power and is
often quoted at 1 watt input and measured
at a 1 meter distance. When designing a
system you want to keep the component
efficiencies as close as possible. Always
match components for efficiency and
complementing frequency response to
ensure smooth transition from
IOW
frequencies to higher ones for accurate
performance. Remember that for every 3
FREQUENCY
[Hz1
dB
of increased efficiency
(SPL)
a speaker has over another, the end performance is as if
the amplifier has doubled it’s power output.
.-
1
I
SPEAKER CONFIGURATIONS can become a problem in autosound installations. We would
like to achieve a sound field in front of us (like a live concert) as compared to sound partly
from the front and partly behind us. This virtually dictates good midrange and tweeter
speakers in front, usually mounted in the doors for good left/right balance, with high-pass
crossovers set greater than 80-100 Hz. For deep bass a subwoofer is required but is nearly
always located behind us in a rear trunk or hatch area. If the subwoofer crossover is too
high in frequency male voices can be heard “gurgling” out of the subwoofer speaker and
therefore pulls the sound-stage to the rear of the car, which is undesirable.
AMPLIFIER POWER is important but should be of lesser importance compared to speaker
choice and placement. Matching the rms (continuous) power levels to that of the speaker
is important but it should be noted that under-powering a system can often cause more
damage than slightly overpowering it. If the speakers are rated for 50 watts rms, you can
often drive them with a 100 watt power amp without concern. IMPEDANCE is the electrical
resistance to AC current flow and is typically 4 ohms for most car speakers. Impedance
loads for a speaker configuration shouldn’t fall below 2-4 ohms for most installations to
avoid amplifier overheating, regardless of manufacturer (Impedance = D.C. resistance of
the voice coil wire + A.C. resistance due to the coil of wire formed).
At some point, the subwoofer speaker must be electrically connected to an
audro
amplifier,
be it a stand-alone unit of some kind or the amplifier built inside the radio. The highest level
of performance will be from the outboard unit in most cases due to its power. To avoid
disapppointing performance we recommend power amplifier levels above 40-50 watts. This
is
NOT
a minimum value; it is simply a nice power point where you begin to really u the
substantial improvements in sound offered by a good subwoofer.
In addition to the amplifier, there needs to be an electrical “crossover” which limits the
frequencies sent on to the subwoofer speaker to only bass type signals. There are two
types of electrical crossovers; ACTIVE and PASSIVE. The Active crossover requires an
interface box (the Active crossover) and connects between the radio and amplifier thus
limiting the frequency range of signal (e.g., below 100 Hz) before it’s sent on to the
amplifier.
The Passive crossover allows the amplifer to reproduce all frequencies (20-20
kHz) and then “brute-force” limits the signal to the low frequencies (e.g., below 100 Hz)
before being passed on to the woofer. The Active crossover offers the highest performance
but is more expensive and has increased installation complexity compared to the Passive
design.
-3-
ACTIVE CROSSOVER SYSTEM
OUTPUT
/
,’
RADIO
/
T-I
AMP
‘~=lx~
‘Xx
a
ACTIVE CROSSOVE
FREQUENCY
1
PASSIVE CROSSOVER SYSTEM
6
dBlOctave
PASSIVE CROSSOVER
<
Inductor Value
W-U
I
80
8.0
100
6.4
150
4.2
200
3.2
I
I
12
dBlOctave
100
150
200
9.0
6.0
4.5
280
iao
140
Sound is created by the movement of the woofer cone back and forth.
If a woofer cone moves
forward creating a positive pressure wave, this same motion creates a negative pressure at the
back of the woofer.
If these
t\iiro
waves combine due to the lack of a wall separating the front of
the speaker sound from the back, the output from the woofer is effectively canceled thus
substantially reducing the bass output of the speaker. This wall is absolutely necessary and is
referred to as an acoustical “baffle”.
It can be accomplished using a box of some kind or simply
the rear package shelf of an automobile to isolate the front and back waves of the speaker.
THIELE-SMALL PARAMETERS
Every woofer has its own electromechanical characteristics which are called THIELE-SMALL
parameters. The three most important parameters include RESONANT FREQUENCY
(“fs” -
the frequency where the speaker moves with the least
mecha’nical
resistance), TOTAL
0
(“Qts” -
the
”
magnification” of the cone movement at its resonant frequency), and
VOLUMETRIC
COMPLIANCE Was” - the equivalent volume of air that the woofer cone can
displace for a given power input). Using these parameters we can then calculate an
optimum box volume for a particular woofer and reasonably predict its frequency response.
.
-4
COMMON ENCLOSURE TYPES
In the car audio world there are 5 types of subwoofer enclosures commonly used; INFINITE
BAFFLE, SEALED BOX (closed box), VENTED BOX (bass reflex), SINGLE-VENTED
BANDPASS
(often incorrectly referred to as “5th” order), and DUAL-VENTED
BANDPASS
(often incorrectly referred to as “7th” order). No single design is superior because each has
its own compromise in performance, power handling, and design complexity. The
bandpass
name implies a “built-in” acoustical response which has a natural
highpass
response (@ 30
Hz for example) but also a
lowpass
response suppressing high frequencies (e.g.,
>80
Hz).
INFINITE BAFFLE designs simply use the trunk of the car
for its acoustical enclosure and the rear deck to isolate the
front and rear sound paths. Advantaaes include simple
0
:
(7
installation and adequate performance for most systems.
Disadvantaaes include poor power handling capability and
substandard transient response.
9
._
:
SEALED boxes offer one of the best compromises in
power handling and performance. Because of the “air
spring” provided by the box the advantaaes include simple
box construction, high power handling, excellent transient
response, and smooth low frequency roll-off.
Disadvantaaes include only moderate efficiencies at low
frequencies and the need for large box volumes.
VENTED boxes extend the low frequency response below
that of the sealed box by using a port tube. Advantaaes
include extended low frequency response, lower distortion
due to smaller cone movements in its passband, good
efficiency, good transient response, moderate size boxes,
and high power capacity. Disadvantaaes include increased
complexity in box design and possible woofer damage due
to over-excursion of the woofer cone below the cut-off
frequency of the vented box.
L
SINGLE-VENTED BANDPASS boxes are relatively new
(about 5 years in the car) but offer some advantages of
both the sealed and vented designs. Advantaaes include
reasonable efficiency, small box volumes, good transient
response, extended low frequency performance, and can
be used with very high power amplifiers. Disadvantaaes
include slightly lower efficiency compared to a vented box
and increased complexity in box design and construction.
DUAL-VENTED
BANDPASS
boxes vent the sound from the
front and back of the woofer through individually tuned
enclosure on the front and rear of the woofer. The
advantaae of this design is its high efficiency over a
narrow frequency band. Disadvantaaes include complex
design and construction, large box volumes, poor transient
response, and susceptibilities to cone over-excursions
(damage) for sound outside its primary frequency band.
%
-5-
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