Velodyne Servo 1200 User manual

Vel od yne
OWNER'S MANUAL
Ser vo 1200
Subwoofer System

SAFETY INSTRUCTIONS
IA
AI
CAUTION: To reduce the risk of electric shock, do not remove cover (or back). No user-serviceable parts inside. Refer
servicing
to qualified service personnel.
The lightning flash with arrowhead symbol, within
an equilateral triangle, is intended to alert the user to the presence of
uninsulated "dangerous voltage" within the product's enclosure that may
be of sufficient magnitude to constitute a risk of
electric shock
to persons.
The exclamation point within
an equilateral triangle is intended to alert the user to the presence of important operating and
maintenance (servicing) instructions
in the literature accompanying the appliance.
1. Read Instructions - All the safety and operating instructions should be read before the appliance is operated.
2. Retain Instructions -The safety and operating instructions should be retained for future reference.
3. Heed Warnings -All warnings on the appliance and in the operating instructions should be adhered to.
4. Follow Instructions -All operating and use instructions should be followed.
5. Water and Moisture -The appliance should not be used near water -for example, near a bathtub, washbowl, kitchen
sink, laundry tub,
in a wet basement, or near a swimming pool, and the like.
6. Carts and Stands -The appliance should be used only with a cart or stand that is recommended by the manufacturer.
7. Wall or Ceiling Mounting -The appliance should be mounted to a wall or ceiling only as recommended by the
manufacturer.
8. Ventilation -The appliance should be situated so that its location or position does not interfere with its proper ventilation.
For example, the appliance should not
be situated on a bed, sofa, rug, or similar surface that may block the ventilation
openings; or, placed
in a built-in installation, such as a bookcase or cabinet that may impede the flow of air through the
ventilation openings.
9. Heat -The appliance should
be situated away from heat sources such as radiators, heat registers, stoves, or ot er
appliances that produce heat.
10. Power Sources -The appliance should be connected
to a power supply only of the type described in the operating
instructions or
as marked on the appliance.
11. Power-Cord Protection -Power-supply cords should
be routed so that they are not likely to be walked on or pinched by
items placed upon or against them, paying particular attention
to cords at plugs, convenience receptacles, and the point
where they exit from the appliance.
12. Cleaning -The appliance should
be cleaned only as recommended by the manufacturer.
13. Nonuse Periods -The power cord of the appliance should
be unplugged from the outlet when left unused for a long
period of time.
14. Object and Liquid Entry -Care should
be taken so that objects do not fall and liquids are not spilled into the enclosure
through openings.
15. Damage Requiring Service -The appliance should
be serviced by qualified service personnel when:
a. The power-supply cord or the plug has been damaged; or
b. Objects have fallen, or liquid has been spilled into the appliance; or
c. The appliance has been exposed to rain; or
d. The appliance does not appear to operate normally or exhibits a marked change in performance; or
e. The appliance has been dropped, or the enclosure damaged.
16. Servicing -The user should not attempt
to service the appliance beyond that described in the operating instructions.
All other servicing should
be referred to qualified service personnel.

For Your Records:
Serial Number
__ _ _ _ ________ _
Date of Purchase
_________ _ _ _
Name of Store
_______ _ _ _ ___ _
OWNER'S MANUAL
VELODYNE SERVO 1200 SUBWOOFER SYSTEM
Congratulations on your purchase of a Velodyne Servo 1200 Subwoofer System. This system represents the
state of the art
in accurate bass reproduction. Read and follow the instructions below to insure safe and proper
system operation. Save this manual for future reference.
Warning: To prevent fire or shock hazard, do not expose this equipment to rain or
moisture. To avoid electrical shock do not open speaker enclosure or amp chassis
cover. Please observe all warnings
on the equipment itself. There are no user
serviceable parts inside. Please refer all service questions to your authorized
Velodyne dealer.
Prior to installation: Please unpack the system carefully. Remove all staples used to seal the carton
as they can
scratch the cabinet. Please save the carton and all packaging materials for future use. Record the serial number
in the space provided above and both locations on the warranty card for future reference.
INSTALLATION
Your new Servo 1200 subwoofer system provides for a number of installation options. Read all the installation in-
formation below
in order to determine which installation option is best for your system. Remember to perform all
installation procedures with system power turned off.
Inputs. The Servo 1200 is equipped with both speaker-level and line-level stereo inputs. Use the LINE IN jacks
when connecting your subwoofer
to a pre-amp, signal processor,or line-level crossover. The FROM AMPLIFIER
jacks connect directly to the speaker outputs of your integrated amplifier or receiver. Your amplifier section will
notice
no additional loading effects when you use these inputs because of their high impedance.
NOTE:
Do not use both line and speaker level jacks simultaneously.
High Pass Crossover. Because your satellite speakers cannot reproduce bass
as accurately as the Servo 1200,
optimum system performance
is attained by rolling off the low end response of your satellites. The Servo 1200 is
equipped with a high pass crossover for this purpose. To use the crossover, simply drive your power amplifier or
satellites from the Servo 1200's outputs.
Interconnection Cables. When installing your Servo 1200 using FROM AMPLIFIER and TO SPEAKERS (as
in
Figure 1) run the same quality speaker cable to your subwoofer as you do to your satellites. If the speaker level
cables to your Servo 1200 will not
be driving any satellites, then a medium guage "zip cord" is sufficient to supply
the subwoofer alone.
Line level cables should
b.e standard shielded phono cables. Always keep leads between your pre-amp and
power amplifier as short as possible.
If necessary, cables to the subwoofer unit a'ione can be qU 'ite long (see
Figure
3).
-1-

INSTALLATION OF SERVO 1200 USING FROM AMPLIFIER INPUTS
Figure 1 shows how to connect your Servo 1200 to a receiver or integrated amplifier. When using the speaker
level terminals, note the right and left channel designations above the terminals. Red speaker jacks are positive,
black speaker jacks are negative (common).
SATELLITE SPEAKERS
AMPLIFIER OR RECEIVER
R L
+ - - +
T<D SPEA
kE~S
+-- +--
~G
n
rR GH EF
I :tJ I :tJ I !) I c> I
117 VAC
50/60 HZ
2AMPS MAX
RIGHT LEFT
+ - + -
I I
FROM
AMPLIFIER
I LEFT II RIGHTI
I ~ I <; J ~ 1( 1
j
LOW PASS
LINE CROSSOVER
.-
70
IN OUT
OLO
8~O
ORO
90 50
'---
100 40
NOTE: RED TERMINALS ARE
POSITIVE, BLACK
TERMINALS ARE NEGATIVE
SERVO 1200
REAR PANEL
Figure 1: Installation Using FROM AMPLIFIER Inputs
Caution: To avoid damage to your main amplifier be sure to make all speaker
connections from RED (positive) to RED and from BLACK (negative) to BLACK. Be
surethat all connections are tight, and thatthere are no loosestrandsor frayed wires.
-2 -

INSTALLATION OF SERVO 1200 USING LINE INPUTS
Figure 2 shows how to install your Servo 1200 between a pre-amplifier and power amplifier. If you are con-
necting to the monaural subwoofer output of a surround sound decoder, then run a single phono cable from the
decoder's sub out to either the right or left LINE
IN jack on the Servo 1200. Leave the unused input a'nd both
outputs disconnected.
SATELLITE SPEAKERS
PRE-AMPLIFIER
MAIN OUTPUTS
L 0
R 0
117VAC
50 / 60 HZ
2AMPS MAX
POWER AMPLIFIER
FROM
AMPLIFIER
~~
l \ ~d~ A I ~ 1. \ ~ ;; l
R L
+ - - +
~ I ~ I
LOW PASS
LINE CROSSOVER
-
IN O UT 70
-E) L G- r- 80m 60
_~ 90~50
100 40
RIGHT
+ -
-
LEFT
SERVO 1200
REAR PANEL
Figure 2: Installation Using LINE Inputs
-3-

INSTALLATION OF SERVO 1200
USING EXTERN AL CROSSOVER
Velodyne offers an optional external high pass crossover unit (part no. 80-111 FIN) for those who wish to use
LINE IN/OUT but must locate their Servo 1200 away from system electronics. By installing the external crossover
near your electronics, all leads between your pre-amp and power amp are kept as short as possible. High fre-
quency integrity is thereby maintained while enabling remote subwoofer installation (see Figure 3).
The external crossover operates at line level only and
is characteristically similar to the high pass crossover
built into the Servo 1200.
PRE-AMPLIFIER POWER AMPLIFIER
R L
INPUTS
SOURCE INPUTS OUTPUTS + - - +
o 0 0 0 R L
o 0 0 0 Q
(---- short leads ~
INPUT HIGH-PASS TO SUB EXTERNAL CROSSOVER
'-------l- -f-C) 1 LEFT 88--+---
L--- - -i--tJr. RIGHT Gl7-- +-- -----.
TO SPEAKERS
rRiGHTl~
I 0 1 1 I 0
0 0
11 7 VAC
50 / 60 HZ
2 AMPS MAX
(---- long leads
LOW PASS
C ROSSOVER
70
8°ffl 60
90 ~ 5 0
100 40
L-} TO SATELLITE
I~ ========== SPEAKERS
SERVO 1200
REAR PANEL
Figure 3: Installation With Optional EXTERNAL CROSSOVER
-4-

INSTALLATION OF TWO SERVO 12005 AS A STEREO PAIR
Although a single Servo 1200 will improve the performance of any audio system, many listeners demand the
additional power and effect of stereo Servo 1200s. Figure 4 shows stereo connection using speaker level inputs.
Note that one pair of input/output terminals remain unused on each unit. Stereo connections can also be made
with the line level inputs.
RECEIVER OR AMPLIFIER
R L
117 VAC
50/60 HZ
SERVO 1200
(RIGHT)
2 AMPS MAX
LINE
IN OUT
LOW PASS
CROSSOVER
70
8°ffl60
90~50
100 40
11 7V AC
50 / 60 HZ
2 AMPS MAX
SERVO 1200
(LEFT)
LINE
IN OUT
LOW PASS
C
ROSSOVER
70
8°ffl 60
90~50
100 40
NOTE: RED TERMINALS ARE
POSITIVE, BLACK
TERMINALS ARE NEGATIVE
RIGHT SATELLITE LEFT SATELLITE
SPEAKER SPEAKER
Figure 4: Stereo SERVO 12005, Speaker Level
-5-

PLACEMENT
The Servo 1200 operates primarily at frequencies below 85 Hz. These frequencies are essentially non-direc-
tional such that you may place the subwoofer almost anywhere without degrading the stereo imaging characteris-
tics of your main speakers.
When using a pair of Servo 1200s
in stereo, it is preferable to place each subwoofer adjacent to the satellite
of the same channel.
Keep
in mind that frequency response and output level can be greatly influenced by placement, depending on
the acoustic properties of the listening room. Typically theServo 1200 will sound louder next to a wall or in a
corner.
Caution: The Servo 1200 amplifier
is built into the woofer cabinet. Do not place
cabinet next to sources of heat such as 'furnace registers, etc. The power cord
should
be routed in such a way that it will not be walked on, pinched, or com-
pressed.
CONTROLS
The control panel on the front of your Servo 1200 includes a power switch, a power-on indicator lamp, and a
level control.
The power switch
is a push-on/push-off type and is located in the upper left position of the panel. The green
indicator lamp comes
on when the Servo 1200 is switched on and properly powered.
The subwoofer level control knob (lower right position)
is used to adjust the volume level of bass information
in relation to the midrange and treble frequencies. We recommend that you begin listening with the level set at the
point midway between MAXIMUM (fully clockwise) and MINIMUM (fully counter-clockwise). Play several selec-
tions of music and vary the subwoofer level until the bass matches the mids and highs to your satisfaction. Once
you set the subwoofer level, you simply use your system's main volume control and the bass proportion will
remain consistent.
The LOW PASS crossover control
is located on the rear panel. It allows you to adjust the upper limit of the
Servo 1200's frequency response. For example, with the crossover set at 60Hz, the subwoofer begins rolling off
above this frequency. Using this control you may match the Velodyne precisely
to your main speakers. If you are
using very sma
ll bookshelf speakers you may wish to raise the low pass as high as 100Hz. If you own large full
range loudspeakers, you may find a lower setting more appropriate.
By fine tuning the level and crossover controls, you can create a seamles blend between the Servo 1200 and
your main speakers, with bass response and output tailored to your listening room and personal preference.
-6-

CARE OF YOUR SUBWOOFER
We recommend using a clean damp cloth for cleaning the cabinet. Never use detergents or abrasives on your
Servo 1200.
The Servo 1200 may be left on continuously without fear of long-term adverse effects. We do recommend that
you turn off the unit during extended periods of nonuse.
PROTECTION CIRCUITRY
Your Servo 1200 is equipped with a special ciruit designed to protect the unit from damage. Either of the two
conditions below will power the unit down and keep
it off for 5 seconds after the fault is corrected.
1) If there is a significant drop in the line Voltage.
2) If there is an input signal which momentarily exceeds the dynamic range of the unit.
TROUBLESHOOTING / SERVICE
Before seeking service for your Servo 1200, please re-check all system and power connections. Also con-
sider the protection circuit described above; you may only need to turn the volume down slightly.
If you determine that your unit requires service, then please contact your local Velodyne dealer.
The following conditions a/ways require service by qualified personnel:
1) If the power cord is damaged
2) If the unit does not appear to operate normally or exhibits a marked change in performance
3) If the unit has been exposed to water
VELODYNE HGS SYSTEM
Velodyne's prime focus is in providing low distortion loudspeaker systems that impress the dedicated audio-
phile as well as the casual listener. Velodyne developed its patented High Gain Servo (HGS) system to bring
nonlinear distortion down to unprecedented levels on its ULD-15 and ULO-18 high performance subwoofers. Your
new Servo Series Subwoofer uses this same HGS technology to reproduce the music you enjoy without the
excessive nonlinear distoritons that plague conventional loudspeaker designs.
The Problem of Distortion
Nonlinear distortion is defined as any form of distortion that moves energy from one portion of the audio
frequency spectrum to another. When a single tone is applied to a nonlinear system, the result is harmonic
distortion,
in which some of the energy leaves the system at integer multiples of the original input frequency.
When multiple tones are applied to the same system, intermodulation tones are produced, usually as simple
combinations of the input frequencies, i.e., sums and differences of integer multiples of the applied tones.
In
general, 3% nonlinear distortion is considered a reasonably small amount. This means that 3% of the total energy
leaving a loudspeaker is at frequencies other than the intended pure tone applied to the input. Our tests, however,
indicate that about
0.5% nonlinear distortion at normal listening levels must be achieved before the average
listener
is truly affected by an improvement in bass response.
In the reproduction of deep bass notes, loudspeakers suffer from a "double-whammy" when it comes to
nonlinear distortion. Fi ,rst, most loudspeakers have much more than even 3% THO (Total Harmonic Distortion) at
-7-

low frequencies. Even at 1 watt drive levels, many loudspeakers have 8 to 10% THO at 40 Hz. With the 50 watt
drive levels needed to produce realistic bass intensity, these distortion figures rise to astonishing levels. Second,
the distortion products produced by a nonlinear woofer are much easier to hear than
is the fundamental fre-
quency. Consider a speaker driven at
30 Hz with 5% 3rd harmonic distortion. If the 30 Hz tone is 90 dB SPL
(Sound Pressure Level), equating
to about 5 watts into a typical woofer, the 3rd harmonic, at 90 Hz, would be
down 26 dB, or at 64 dB SPL. However, humans are more than 10 times
as sensitive to sound at 90 Hz than at 30
Hz. The nonlinear distortion produced by a woofer must be weighted by the sensitivity function of the human ear.
When this
is done, it becomes clear that even a small percentage of harmonic distortion is unacceptable in a bass
driver.
It is also clear that high-order (3rd, 4th, 5th, etc.) harmonic distortion products are more serious than are
2nd harmonic distortion products. These studies have led to the conclusion that 0.5%
is the maximum tolerable
amount of nonlinear distortion for a bass driver, and the less distortion the driver produces, the more capable it
is
of accurately reproducing live sounds.
Since most woofers today have at least 10% THD when 0.5%
is the maximum tolerated, minor improvements
in woofer techno~ogy are essentially ineffective. Servo Series Subwoofers have about 90 times less nonlinearity
than a typical
10 inch bookshelf speaker. They have about 3 times less distortion due to their greater size and
power handling capability, and about
30 times less distortion due to the Servo feedback loop. The improvement is
even greater if one considers exceptionally loud and deep tones such as organ pedal notes.
An interesting result of this reduced distortion is that much of the bass, when played over a servo Series
Subwoofer, seems to actually
be reduced. The truth, of course, is that the "missing" bass was never really there
on the source material, and was never intended to be played by the artist. Distortion products introduced by
conventional woofers actually make the entire bass spectrum sound louder.
Our Solution
The Velodyne Servo Series Subwoofer System produces sound in the same manner as any conventional
loudspeaker: a cone-shaped piston
is forced to move by means of a linear motor composed of a coil situated
between the poles of a very strong permanent magnet.
In the Servo Series, however, this linear motor is a servo-
motor, meaning that the motor
is linked to the power amplifier as part of a control system. The basis for the control
action
is the signal obtained from an accelerometer which is rigidly fastened to the voice coil. The strategy of
continuously monitoring the cone motion, and using this information
as the basis 'for the corrective action, is called
motional feedback. This feedback technique is illustrated
in the system block diagram, Figure 5.
The signal into the system is a time varying voltage which is an exact analog of the desired acoustic output
from the loudspeaker. The accelerometer output contains sufficient information to deduce the actual acoustical
output of the woofer. The servo circuitry compares almost instantaneously how well the acoustic output matches
the command signal coming
in. If and when there is a deviation, the servo circuitry modifies the drive signal to the
amplifier
so that the acoustic output from the speaker is a true representation of the input.
In conventional loudspeakers, the drive signal into the speaker is virtually free from distortion but the
speaker's acoustical output may be highly distorted.
In Servo Series Subwoofers, the speaker coil drive signal is
often highly distorted, or actually pre-distorted, in exactly such a way that the acoustical output from the speaker is
free from distortion. Motional feedback has been used previously in an attempt to make small woofers sound like
larger, more powerful ones. At Velodyne, the use of motional feedback
is applied to make what is already a large
and powerful woofer achieve a level of performance that has never before been reached
in a home entertainment
product.
HGS System Components
(Refer to Figure 5)
High and Low Pass Crossovers receive the incoming audio signals from your system pre-amp or power amp.
Frequencies above 85 Hz are diverted to your power amplifier while frequencies 'from the right and left channels
below 40 to 100
Hz (depending on low pass crossover setting) are summed to monaural and passed on to
subsequent stages in the subwoofer.
Loop/Control Stage. Incoming bass signals pass through a variable gain amplification stage designed to protect
the subwoofer from being overdriven (see Supporting Circuits below). With a bit of added filtering, the bass signal
is now ready to be compared with the feedback signal of the accelerometer. A composite signal is created which
compensates for erroneous movement
of the cone.
-8-

INPUT FROM
HOST SYSTEM SUPPORTING CIRCUITRY
PRE-AMPLIFIER
~
t
HIGH-AI'JD
LOW- PASS LOOP / CONTROL
CROSSOVERS
CUSTOM DRIVER
HIGH-PASS OUTPUT
TO HOST SYSTEM
POWER AMPLIFIER
OR SPEAKERS
FEEDBACK SIGNAL
ACCELEROMETER
AND AMPLIFIER
Figure 5: Servo Series System Block Diagram
Power Amplifier. The Servo 1200's amplifier must provide power for distortion correction as well as basic music
reproduction.
Custom Driver. Although our HGS electronics play the most important role in reducing distortion, the Servo
Series driver must be carefully engineered and constructed so as not to undo the work that the HGS electronics
have done. A large magnet and voice coil are used to improve sensitivity, the cone is specifically shaped to
reduce resonances, and ventilation holes are used liberally to eliminate whistling noises often associated with
long-travel operation (essential for producing low frequencies at listenable volumes).
Accelerometer. Perhaps the most critical component of the HGS system, the accelerometer measures the
motion of the cone and relays
it back to the loop circuits by means of an onboard charge amplifier and special
feedback circuitry.
Supporting Circuits. A GAIN COMPRESSION circuit evaluates the amplitude of the incoming bass signal. The
gain compressor
is directly linked to the control stage and can thereby limit input signal gain in order to prevent
amplifier clipping. If
an extremely loud transient is detected, the gain compressor circuit will signal the COMPARA-
TOR circuit to immediately shut down the subwoofer's power amplifier for five seconds. The comparator circuit will
also Sllut down the power amplifier if
it detects problems with the power supply.
VELODYNE, Servo 1200, ULD-15, and ULD 18
are registered trademarks of Velodyne Acoustics, Inc.
Velodyne Acoustics, Inc.
1070 Commercial Street
San
Jose Ca., 95112
[phone]
-9-

VELODYNE SERVO 1200 ™
SUBWOOFER SYSTEM SPECIFICATIONS
Type:
Power:
Stereo Input:
Diameter:
Linear travel:
Voice Coil:
Magnet:
Cone:
Accelerometer:
High Pass:
Low Pass:
Finish:
Dimensions:
Volume:
Weight:
Grill:
Servo Loop Gain:
Servo Loop Feedback Rate:
Maximum Distortion (25 Hz @ 104 dB):
Frequency Response:
Driver Resonant Frequency:
Damping Facto
r:
Protection:
Warranty:
Amplifier
Integrated Class A/B.
100 watts continuous RMS, 400 watts peak.
Line level sensitivity -100 mV
/1 OK nominal
Speaker level sensitivity - 1 volt nominal
Driver
12 inches.
9 11 6" peak to peak.
Copper; 23/8" Diameter, 1.1" Length.
56 oz.
Resin impregnated fiber.
Piezo with integral amplifier.
Crossover
Passive, 85 Hz nominal. 6 dB per octave.
Active, Dual slope, adjustable from 40 Hz to 100 Hz.
Slope, 6 dB per octave initial, 24 dB per octave ultimate.
Cabinet
Black, Vinyl woodgrain
(H) 16 1/4", (W) 18 1/4", (D) 18 1/4".
3000 cu. in.
601bs.
Black Knit.
Servo
26 dB.
3500 corrections per second.
<.5%
20 Hz low, 40 Hz-100 Hz high
(depending
on crossover setting).
<4 Hz
>1000
Low Voltage, Excessive Signal.
2 years.
Specifications are subject to change without notice.