Velodyne Acoustics Speaker DF 12sc User Manual

"...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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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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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.  
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.  
5
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