rofessional
Quality Subwoofers
Technical Manual For:
Manuel
Tkchnique
Pour:
Manuel
Tbcnico Para:
PC& PCIO,
Cl!&
ad PC15
Rnsch
Telecam
TOPICS
New Pro Component features
System design guidelines
Subwoofer enclosure types
Subwoofer enclosure construction
System installation guidelines
Additional reference information
Limited warranty information
Technical support
PC 8
technical specifications and recommended box designs
PC 10 technical specifications and recommended box designs
PC 12 technical specifications and recommended box designs
PC 15 technical specifications and recommended box designs
Technical support summary sheet (fax sheet)
PAGES
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2
334
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SUJETS
Caracteristiques des nouveaux composants Pro
Principes de conception du
systeme
Types d’enceintes de subwoofer
Construction d’enceintes de subwoofer
Principes d’installation du systeme
References
Garantie
limitee
Soutien technique
PC 8:
specifications techniques et conception recommandee des enceintes
PC 10: specifications techniques et conception
PC 12: specifications techniques et conception
PC 15:
specification$
techniques et conception
Demande de soutien technique (feuille de fax)
recommandee des enceintes
recommandee des enceintes
recommandee des enceintes
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TEMAS
Nuevas Caracterkticas Pro Component
Principios de
disefio
del sistema
Tipos de
caja
del altavoz
para
bajas frecuencias
Construction de la
caja
del altavoz
para
bajas frecuencias
Principios de
instalacion
del sistema
Information de referencia adicional
Information
de la garantfa
limitada
Apoyo
Tecnico
PC 8
especificaciones tecnicas y
diseflos
recomendados de la
,caja
PC 10 especificaciones tecnicas y
disefios
recomendados de la
caja
PC 12 especificaciones tecnicas y
disefios
recomendados de la
caja
PC 15 especificaciones tecnicas y
diseAos
recomendados de la
caja
Hoja de resumen de apoyo
tecnico
(hoja fax)
.
PAGINAS
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2’,
&
31,32
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Components in order to introduce a series of subwoofer speakersaffering unparalleled value in
the car audio market. The PC performance standards were increased yet we were able to drive
the speaker costs down using improved manufacturing techniques and high technology
materials.
In addition to improved performance, the quality standards have been increased substantially.
A car may see temperature extremes ranging from -40” to nearly 200” F driving from Minnesota
to Arizona. Because of these extremes, our engineers subject their designs to long-term
temperature, humidity, and vibration testing to ensure product life spans exceeding that of most
cars.
This manual is composed of several sections and offers brief discussions in each area.
New PRO COMPONENT FEATURES lists technical advancements of the pc 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.
LLATION
GUIDELINES examines additional automotive installation concerns and
IONAL 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 PC 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
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
tc
danp
n
Polyamide voice coil bobbins with
1’
,rcoat”
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-
IMPROVED 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 work 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
folio*
.’
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.
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 speaker 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-burl) is the
system’s ability to reproduce the sound signature of a trumpet so that it doesn’t sound lik
trombone. LINEARITY is the systems ability to provide consistent frequency response
regardless of volume setting. Some systems sound “shrill” at high levels if the tweeters are
over driven. They may also sound weak at low volumes due to our psychoacoustic hearing
effects which we perceive
b&s
loss at low levels.
-2-
SYSTEM PLANNING
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 (This is usually
addressed
by individual manufacturers
so
it's
a safe bet to buy from one company.).
Always match components for efficiency and
complementing frequency response to
”
z
.
d
ensure smooth transition from low
FREQUENCY
rtkl
frequencies to higher ones for accurate performance. Remember that for every 3 dB of
increased efficiency (SPL) a speaker has over another, the end performance is as if the
amplifier has doubled it’s power output.
KER CONFIGURATIONS can become a problem in autosound installations. We would
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
hi
h in frequency
male voices can be heard “gurgling” out of the subwoofer speaker and there ore
B
sound-stage to the rear of the car, which is undesirable.
pulls the
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).
forward creating a positive pressure wave, this same motion
creates
a negative pressure at the
back of the woofer. If these two 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 absolutelv 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 a car to isolate the front and back waves of the speaker.
THIELE-SMALL PARAMETERS
Ev6woofer
has its own electromechanical characteristics which are called
THIELESMALL
F
eters.
tt:
_
The three most important parameters include RESONANT FREQUENCY
(“fs” -
dquency
where the speaker moves with the least mechanical resistance), TOTAL
Q
-
the “magnification” of the cone movement at its resonant frequency), and VOLUMETRIC
(“Qts”
COMPLIANCE
(‘l/as” -
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 predict its associated frequency response.
-3-
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
(~80
Hz for example).
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. Advantages include simple
installation and adequate performance for most systems.
Disadvantages include poor power handling capability and
substandard transient response.
SEALED boxes offer one of the best compromises in power
handling and performance. Because of the “air spring”
provided by the box the advantaqes 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, good efficiency, good
transient response: moderate size boxes, and high power
capacity. Disadvantages 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.
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 good
efficiency, small box volumes, good transient response,
extended low frequency performance, and can be used with
very high power amplifiers. Disadvantages 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
advantaqe of this design is its high efficiency over a narrow
frequency band. Disadvantages include complex design and
construction, large box volumes, poor transient response,
and strong susceptibilities to’cone over-excursions (damage)
for sound outside its primary frequency band.
-4-
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