"...I rank the quality, if not the magnitude, of this small California
company's achievement up there with Dolby noise reduction and
the Compact Disc."
Models DF-12sc & DF-10sc
OWNER'S MANUAL
12" & 10" Distortion Free (DF) Series
-David L. Clark
Audio, Nov. 1990
on Velodyne's servo-controlled
subwoofer systems.
Automotive Servo-Controlled Subwoofers
Superior Design For Superior Sound
"The servo-feedback subwoofers, in our experience, produce the
purest low frequency sounds of all the designs."
-John E. Johnson, Jr., Ph.D.
Secrets of Home Theater and High Fidelity, Jan. 1995
on Velodyne's servo-controlled
subwoofer systems.
"... it's safe to say that when it comes to woofin' done right,
Velodyne's bigger models are probably the safest bet there is."
"If you know subwoofers, you know about Velodyne."
-Corey Greenberg
Home Theater Technology, Feb. 1995
Face Off: Comparison of five subwoofers
Velodyne Acoustics, Inc.
1070 Commercial St. Suite #101
San Jose, CA 95112
AUTOMOTIVE
DISTORTION-FREE
SUBWOOFER
408.436.7270 voice
408.436.7276 fax
Printed on recycled paper.
Velodyne, DF-12sc & DF-10sc are trademarks of Velodyne Acoustics, Inc.
For installation & connections, see the sup-
plied installation / connections manual.
Congratulations!
Thank you for purchasing a Velodyne product. Your purchase of a
Velodyne servo-controlled subwoofer for the automobile shows a
desire to achieve the highest possible quality of sound reproduc-
tion. This product has been engineered and built to the highest
standards to provide you with years of listening pleasure.
Warranty & Service Information
The DF-series servo-controlled subwoofers represent a break-
through in car audio technology. By designing the speaker and
proprietary control circuitry from the ground up, we have reduced
distortion to an order of magnitude below that of the best speakers
currently available. After you listen, we think you'll agree. For the
lowest distortion speakers around, there is only one choice. Velo-
dyne, the bottom line in bass.
This product is constructed of the highest grade materials and
assembled under the strictest possible quality assurance condi-
tions.
Should a situation arise which leads you to believe the product is
malfunctioning, please return to your authorized Velodyne dealer
first.
Care Of Your Velodyne
Should the product require repair or service, your Velodyne dealer
is required to send the product in to Velodyne directly, we do not
authorize outside service stations to make repairs to this product.
This product combines both electronic devices and loudspeakers.
Care must be taken not to damage either unit. Please take every
precaution possible when installing and using the product so
damage does not occur.
If you have any additional questions concerning the specific war-
ranty coverage, please consult the supplied warranty & registration
card.
ꢀꢀDo not allow objects to come in contact with the clear anodized
aluminum cone, as the cone is very delicate.
Any additional questions which are not covered in this manual
should be directed to either your authorized Velodyne dealer or
contact us directly at Velodyne . . .
ꢀꢀUse only damp cloth when cleaning either controller housing or
speaker. No harsh detergents or chemicals that may damage
thesurface.
Velodyne Acoustics, Inc.
1070 Commercial St. Suite #101
San Jose, CA 95112
ꢀꢀNever expose the Servo-Controller housing to moisture.
ꢀꢀDO NOT try to adjust the setup controls in control unit. Refer all
adjustments to an authorized Velodyne dealer/installer.
408.436.7270 voice
408.436.7276 fax
ꢀꢀIf any part of your Velodyne Servo-Controlled subwoofer or
controller should require service, return unit to your authorized
dealer. There are no user serviceable parts inside.
ꢀ
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2
Servo Technology
Practice Safe Sound
Velodyne pioneered the use of servo-control technology as a
means of reducing distortion over a decade ago. Now, we are the
first to offer this revolutionary technology for use in the automobile.
WE WANT YOU LISTENING FOR A LIFETIME!
Used wisely your new sound reproduction equipment will provide
you with a lifetime of listening pleasure. Unfortunately, hearing
damage from exposure to loud noise is often undetectable until it is
too late. Since it is all too easy to keep "turning up the volume" so
you can overcome road noise, we would like to issue this word of
caution. Velodynerecommendsthatyouavoidprolongedexposure
to excessive sound pressure levels. The following list is included for
your protection.
In normal music listening, we are exposed to many forms of
distortion. Every component in the signal path adds it's own char-
acteristicdistortiontothesignal. Sincemosthighqualityelectronics
available now have distortion levels far lower than we are able to
hear, that leaves your speakers as the worst offenders. While we
scrutinize distortion specifications before we buy an electronic
component, we rarely see anyone list distortion on loudspeakers.
That is because traditional subwoofers (even high quality types)
can produce distortion levels around 25% at typical levels. Even at
only one watt input power, many subwoofers produce from 8-10%
distortion.
Decibel Level
40 dB
Example
Traditionalspeakersproducesoundbyusingaconewhichisforced
to move by an electromagnetic motor. The motor is connected
directly to an amplifier, which provides the necessary increase in
power to drive the speaker. If a speaker was functionally "perfect",
this method would work fine. The problem arises when the fast
moving speaker cone is called upon to stop & change direction
quickly. The speaker cone may continue to move, resulting in
muddy bass with an increased amount of harmonic distortion.
Unfortunately there is no way for this traditional system to "control"
distortion. Until now.
Quiet library, soft whispers
Typical quiet room
50 dB
60 dB
Office equipment, background noise
Vacuum, hair dryer, restaurant
Average city traffic
70 dB
80 dB
Sustained exposure to levels of noise higher than this can be
dangerous to your hearing.
90 dB
Subway, motorcycle, lawn mower
Garbage truck, power tools
Live rock concert
100 dB
120 dB
140 dB
180 dB
Velodyne's patented servo-control system uses a "motional feed-
back loop", which corrects for any distortion. Here's how it works.
The music signal that normally goes to your amp is re-routed to our
control unit. This unit monitors the music signal, which should be
reproduced exactly without distortion. We then mount two acceler-
ometers on the speaker. One accelerometer monitors cone motion,
while the other accounts for motion of the vehicle. Now that we can
monitor the actual motion of the cone, we can instantaneously
compare how well the acoustic output of the speaker matches the
musicsignal. If&whentheoutputfromthespeakerstartsto deviate
from the music signal, the servo circuitry modifies the drive signal
Gunshot (close range), jet plane
Rocket launching pad
Information courtesy of Deafness Research Foundation.
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3
8
The Velodyne Story . . .
to the amplifier. Forcing the speaker's acoustical output into a true
representation of the music.
Founded in 1983 by David Hall,
The term "servo" is misused by some manufacturers who use a
differentmotorontheirspeakerstotryandmakewooferssoundlike
larger more powerful units. Unfortunately this usually results in a
large amount of distortion as well. At Velodyne, we take an already
large & powerful speaker, then use motional feedback to create a
true"servo"controlledspeaker.Thisreducesdistorionandachieves
a level of sound quality never before heard of.
Velodyne Acoustics is the result of an
effort to bring the discipline of me-
chanical engineering and the doctrine
of common sense to the field of high
performance audio- the Silicon Valley
approach to sound.
Through innovative thinking and
inventive design, the company pio-
neered the first true servo-controlled
subwoofers. The result was both the
reference standard for bass repro-
duction and the foundation for distor-
tion-free listening.
Product Features & Controls
ꢀꢀRigid cast aluminum basket
ꢀꢀRubber surround for long excursion and durability
ꢀꢀRigid spun aluminum alloy cone
ꢀꢀ2-1/2" high temperature voice coil
ꢀꢀForced air cooling of voice coil
Rejecting the trend toward high-end
indulgence or fancy marketing gim-
micks with no relevance to improving
sound, Velodyne devoted its techni-
cal resources to bringing the benefits
of ultra-low distortion technology
within the reach of all dedicated
music lovers. In fact, many state of
the art recording studios & homes
now feature Velodyne subwoofers as
their "reference standard" by which
all others should be judged.
ꢀꢀGold binding posts accept large guage wire
ꢀꢀPatented High-Gain-Servo control
ꢀꢀSelectable subsonic filter (10 or 30 hz)
ꢀꢀSelectable low pass crossover frequency (60 to 120 hz)
ꢀꢀOptional bypass for low pass crossover
ꢀꢀRemote mounted digital volume control (user adjustable)
ꢀꢀPhase selection (0, 90, 180, 270)
ꢀꢀEnclosure type selection; sealed, infinite baffle, etc.
ꢀꢀLow frequency equalization circuit; to allow use with most
amps on the market
ꢀꢀDelayed turn on/off; prevents pops & thumps
ꢀꢀGain compression circuit; to prevent woofer from over
excursion
ꢀꢀInput overload protection
ꢀꢀThermal power sensing; protects woofer's voice coil from
burnout
With the introduction of Velodyne's
Distortion Free Series for the automo-
bile, listeners finally have access to
all the details and dynamics that
make up the modern listening experi-
ence. Anything imperfect originates
elsewhere. By design, Velodyne
speakers are incapable of error.
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7
4
System Design Suggestions
Servo-System Signal Flow
The Velodyne product you have purchased was designed to offer
you the greatest amount of flexibility possible in your vehicle's
sound system. However, due to the nature of the servo-control
circuitry, there are some suggestions you should observe to avoid
any problems and ensure maximum performance. Please read and
observe these requirements before proceeding with system instal-
lation.
S I G N A L
S O U R C E
ꢀ
S E R V O
C O N T R O L
U N I T
ꢀꢀWhen choosing an amplifier, it must have extended low
frequency response down to at least 10 hz
ꢀꢀOptimum performance is typically realized with one dedi-
cated amplifier per woofer
ꢀ
ꢀꢀAmplifier used must have gain adjustment
ꢀꢀAmplifier used should be capable of supplying woofer with
a minimum of 100 watts RMS
AMPLIFIER
ꢀꢀMaximum suggested amplifier power is 300 watts RMS
ꢀꢀWhen installed in a sealed enclosure, the unit may require
an amplifier towards the high end of the scale (200-300w);
when used in an infinite baffle setup, power requirements
are reduced and satisfactory performance may be attained
with a smaller amp (100-200w)
ꢀ
ꢀꢀSealed enclosures: accurate sound, simple to build but
require more amp power than other enclosures
ꢀꢀInfinite baffle: accurate sound, simple installation, lowest
power requirements
SPEAKER
ꢀꢀPorted enclosures: much higher output, low power require-
ments but more complex to build
As you can see from this diagram, the speaker and amplifier now
become part of a loop. Actual cone motion is monitored, so now we
can control the drive signal to the amplifier. In essence, controlling
how the speaker responds.
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