������
�����
������
�����
������
�����
Setting Up and Using Your Servo Series
The Servo Series Protection Circuitry
Bridge Mode
6
7
8
Specifications
10
11
12
Appendix A: Power Output vs. THD
Appendix B: Frequency Response
Copyright 2005, Samson Technologies Corp.
Printed March, 2005
Samson Technologies Corp.
575 Underhill Blvd.
P.O. Box 9031
Syosset, NY 11791-9031
Phone: 1-800-3-SAMSON (1-800-372-6766)
Fax: 516-364-3888
Thank you for purchasing the Servo Series Power Amplifier from Samson Audio! We know you don’t like reading own-
ers manuals, but you’ve just purchased one of the finest sound reinforcement power amplifiers around, and we want
to tell you about it. So, before you plug in, we’d like to suggest you take just a few moments out to scan these pages.
We’ll make it as painless as possible, we promise—and, who knows, you might just pick up a tip or two.
The Samson Servo Series stereo power amplifiers have been designed to provide robust, clean output with low distor-
tion and wide dynamic range, along with the dependability demanded by the most professional audio engineers and
Their convenient 2 rack-space design is compact, and yet there’s plenty of power available, with 2 x 66 Watts at 8Ω, 2
x 100 Watts at 4Ω for the Servo 200, 2 x 100 Watts at 8Ω, 2 x 150 Watts at 4Ω for the Servo 300, 2 x 225 Watts at 8Ω, 2 x
300 Watts at 4Ω for the Servo 600, over the full frequency spectrum, from 10 Hz to 55 kHz.
For mono applications, a Bridge mode links both channels of the amplifiers, thus providing even more single channel
power, with power ratings of 200 watts for the Servo 200, 300 watts for the Servo 300, 600 watts for the Servo 600 into
a 8 ohms load.
the outputs, the Servo Series amplifiers provide standard 5-way binding posts and 1/4”phone jacks. Front-panel con-
trols and displays include a power switch with LED indicator, as well as independent left and right channel input level
controls. To help you set the correct operating levels, the Servo Series amplifiers include front panel Signal, Peak and
Protection LED indicators. There's also a ten-segment Level VU meter to help you set a good operating level.
Like all serious power amplifiers, the Servo Series internal electronics are based around a serious power-core, with
over-sized toroidal transformers and large extruded heat sinks. To keep the amplifiers running cool, their
design employs twin internal wind tunnels with forced-air cooling via two temperature-sensitive, variable speed fans,
which greatly reduce the chance of thermal and overheating problems. Multi-stage protection for power-up, over-
heating, over-current, short circuit, low output impedance and DC voltage, assures high reliability under the most
demanding situations.
The Servo Series amps are road tough with their all steel chassis and19-inch rack mount design. The Servo Series
amplifiers are ready for a life on the road, or to make their home in a nice fixed installation.
Optimized for live sound venues, houses of worship, commercial installations, and for driving small and medium-sized
live PA systems, the Servo Series amplifiers will deliver reliable power from gig-to-gig, venue-to-venue and day-to-
night.
In these pages, you’ll find a detailed description of the many features of the Servo Series power amplifier, as well as
a guided tour through its front and rear panels, step-by-step instructions for its setup and use, and full specifications.
You’ll also find a warranty card enclosed—please don’t forget to fill it out and mail it in so that you can receive online
technical support and so we can send you updated information about these and other Samson products in the future.
SPECIAL NOTE: Should your Servo Series ever require servicing, a Return Authorization number (RA) is necessary.
Without this number, the unit will not be accepted. If purchased in the United States, please call Samson at 1-800-372-
6766 for a Return Authorization number prior to shipping the unit. If purchased outside the United States, contact
your local Samson dealer for details. Please retain the original packing materials and, if possible, return the unit in its
original carton and packing materials.
������
���������
�����
The Samson Servo Series power amplifier utilizes the latest technology in professional power amplifier design. Here are some of
• Power to spare - Each amplifier delivers the following power ratings.
• For mono applications, a Bridge mode links both channels of the amplifiers, thus providing even more power, with power rat-
ings of 200 watts for the Servo 600, all driving an 8 Ohm load.
• Clean, crisp sound - Impressive audio specifications such as 0.04% THD, dynamic range of 105 dB, crosstalk of 80 dB, and fre-
quency response of 10 Hz to 55 kHz guarantee ultra-clean sound quality.
• Independent input level controls for each channel allow precision adjustments.
• 10 segment LED signal indicators for each channel continuously display power output levels and allow you to correct for
overloading (clipping) conditions.
• Unique stable bipolar circuit design that continuously keeps DC output during idling at or near zero volts (thus keeping idle
speakers at their zero point). This serves to minimize heat overload problems by effectively preventing the Servo Series from
applying power when unnecessary.
• Forced air cooling via two temperature-sensitive, variable speed fans provides reliable performance without thermal and
overheating problems.
• Protection relay circuitry (with dedicated LEDs for each channel) that guards against overheating or faulty wiring conditions
and also prevents “thumps”when powering on or off. This means that you can use the Servo Series with a single power strip
into which a mixer or other audio devices are connected, without danger of damage to connected speakers.
• Input connectors for each channel accommodate both RCA or balanced 1/4-inch TRS plugs.
• Output connections are made via 5-way binding posts
• Toroidal transformer power supply for high current and low profile.
• User-resettable circuit breaker for fast, easy startup following a power supply overload.
• The Servo Series can be mounted in any standard 19" rack (taking just two rack spaces), making it easy to integrate the amp
into any fixed or traveling PA rig.
• Rugged construction (an all-steel chassis with a cool gray finish and a lightweight anodized aluminum heat sink) makes the
Servo Series eminently roadworthy.
• Extended three-year warranty.
• Last but certainly not least, value. The Samson Servo Series has been designed from the ground up to deliver excellent yet
affordable sound quality
3
�
�
�
�
�
�
�
������
���������
�����
�
�
�
�
�
�
- The Servo Series amplifiers stay cool thanks to their twin, forced-air cooling tunnels. Cool air is drawn through
the front panel fan vents, reducing the temperature of the internal components while forcing the heat out the rear vents.
The fans will actually sense the internal temperature and adjust their speed to maintain the optimum cooling conditions.
2: Channel input level controls - These 42-position detented controls allow you to precisely adjust the input level of the
signal arriving at the rear-panel input jacks (see #1 and #5 on the following page). At their fully counterclockwise posi-
tion (labeled “MIN”), the signal is attenuated by 80 dB (essentially completely off). At their fully clockwise position (labeled
“MAX”), the signal is at unity gain (that is, no attenuation). When +4 dBu of signal arrives at the input jacks and the Channel
input level controls are set to their fully clockwise position, the Servo Series delivers full power output.
3: LED meters - These ten-segment LED meters continuously monitor the power output level for the corresponding chan-
nel. For convenience, the segments are labeled, from left to right, -24 dB, -20 dB, -16 dB, -12 dB, -8 dB, -4 dB, -2 dB. O, +2 dB
and +4 dB (PEAK). The right (PEAK) segment lights whenever the channel is outputting signal at full strength. For the best
signal-to-noise ratio, the right (PEAK) segment should light occasionally during peak levels; if it lights frequently, you may
be overloading the amplifier and a distorted (“clipped”) signal is probably being output. If this occurs and backing off the
Input Level control delivers too low an output level for your application, consider using Bridged mode (see the “Bridged
Mode”section on page 8 in this manual for more information).
4: Power switch - Use this to power the Servo Series on or off. The internal LED lights whenever the Servo Series is powered
on.
5: Signal LED - The front panel LED indicators continuously monitor the power output level for the corresponding channel.
The SIGNAL LED lights whenever output signal is present.
6: Protection LED - This goes on for approximately five seconds whenever the Servo Series is powered on and then turns
off (you’ll hear a “click”when it does so). The Protection LED will also light when overheating or other severe problems occur
(see page 6 in this manual for more information). It is normal for the Protection LED to fade slowly when the amp is pow-
ered off. When lit, no signal is provided to any connected speakers, thus muting them and preventing any “thump”from
occurring. For a complete description of the conditions under which this light goes on, see the section entitled “The Servo
Series Protection Circuitry”on page 7 of this manual.
7: Peak LED - The PEAK segment lights whenever the channel is outputting signal at full strength. For the best signal-
to-noise ratio, the right (PEAK) segment should light occasionally during peak levels; if it lights frequently, you may be
overloading the Servo Series and a distorted (“clipped”) signal is probably being output. If this occurs and backing off the
Input Level control delivers too low an output level for your application, consider using Bridged mode (see the “Bridged and
Parallel Modes”section on page 8 in this manual for more information).
�
�
�
�
�
�
�
�
�
�
�
�
1: RCA Input connectors – You can connect unbalanced incoming signals to the Servo series using the RCA connectors, which
are wired as follows: Pin 2 (or Tip) hot, and Pin 1 (or Sleeve) ground. The Servo Series accepts input levels of any strength but
needs at least -10dBV dBu to achieve maximum power. Stereo signals should be connected to both the Channel 1 and Channel
2 input jacks; however, when operating the Servo Series in Bridged mode, use the Channel 1 input jack only. See page 8 in this
manual for more information about Bridge mode and page 9 in this manual for full interconnection instructions.
2: Fan - This variable-speed fan provides vital cooling to your Servo Series (the hotter the amp gets, the faster the fan blows!).
Make sure that both the front and rear panels are kept free of all obstructions and that cool, fresh air is accessible at all times.
Also, try to ensure that the Servo Series is used in a dust-free environment.
3: 1/4-inch Output Connectors - Use these to connect each channel of the Servo Series to, 4-ohm or 8-ohm loudspeakers with
1/4-inch input jacks. See page 8 in this manual for more information about Bridged mode and page 9 in this manual for full
speaker connection instructions.
4: 5-way Binding Post - Use these to connect each channel of the Servo Series to 4-ohm or 8-ohm loudspeakers. Be sure to con-
nect the loudspeaker correctly, with the red (+) terminal normally connected to the positive input of the speaker and the black
(ground) terminal normally connected to the negative input of the speaker. See page 8 in this manual for more information
about Bridge mode and page 9 in this manual for full speaker connection instructions
5: 1/4-inch Input Connectors - Connect incoming signals to these electronically balanced inputs, using the 1/4”TRS (Tip/Ring/
Sleeve) plugs, wired as follows: Pin 2 (or Tip) hot, Pin 3 (or Ring) cold, and Pin 1 (or Sleeve) ground. We recommend the use of bal-
anced three-conductor cabling wherever possible (unbalanced two-conductor 1/4”plugs can also be inserted into these inputs,
but you’ll get better signal quality and less outside noise and hum if you use balanced lines). The Servo Series accepts input levels
of any strength but needs at least +4 dBu to achieve maximum power. Stereo signals should be connected to both the Channel
1 and Channel 2 input jacks; however, when operating the Servo Series in Bridged mode, use the Channel 1 input jack only. See
page 8 in this manual for more information about Bridge mode and page 9 in this manual for full interconnection instructions.
6: AC input - Connect the supplied heavy-gauge 3-pin “IEC”power cable here.
7: Bridge / Stereo switch - For normal operation, place this two-way switch in its lower (“STEREO”) position. When placed in its
upper (“BRIDGE”) position, the signal arriving at the Channel 1 input only is again routed to both power amplifiers (again, the
Channel 2 input is ignored), but the two power amplifiers are bridged together. For more information, see the “Bridge Mode”
section on page 8 in this manual and the “Servo Series Connections”section on page 9 in this manual. WARNING: Due to the
extremely high power output of the Servo Series when used in Bridge mode, be sure to use only loudspeakers sufficiently rated to
handle the resultant wattage (in Bridge mode, these must be 8-ohm speakers).
5
Setting Up and Using Your Servo Series
Setting up your Servo Series is a simple procedure which takes only a few minutes:
1. Remove all packing materials (save them in case of need for future service) and decide where the
amplifier is to be physically placed—it can be used free-standing or mounted in a standard 19”rack,
requiring only two rack spaces. When installed, make sure that both the front and rear panels are
unobstructed and that there is good ventilation around the entire unit (we recommend the use of
spacer panels, especially if multiple amplifiers are used in a rack.)
Bridge / Stereo switch
2. Set the rear panel Bridge/ Stereo switch as desired (see the “Bridge Mode”section on page 8 in this
manual for more information).
3. Make the speaker connections, using the banana or 1/4-inch output connectors on the rear panel.
It is never a good idea to power up any amplifier that is not connected to loudspeakers. When oper-
ating in Stereo mode, any loudspeakers with a minimum impedance load of 4 ohms (that is, 4 ohms
or greater) can be used; however, in Bridged mode, 16 or 8 ohm speakers must be used. Be sure to
connect the loudspeaker correctly. In Stereo mode, make sure the red (+) terminal is connected to
the positive input of the speaker and the black (ground) terminal is connected to the negative input
of the speaker. See page 8 in this manual for more information about Bridged mode and page 9 in
this manual for full speaker interconnection instructions.
Output connectors
4. Next, make the signal input connections, using the RCA or 1/4-inch input connectors on the rear
panel (if operating the Servo Series in Bridged mode, use the Channel 1 input only—see page 8 in
this manual for more information). If your mixer or crossover network has balanced outputs, we rec-
ommend the use of three-conductor cabling and connectors (unbalanced two-conductor plugs can
also be inserted into the 1/4-inch inputs, but you’ll get better signal quality and less outside noise
and hum if you use balanced lines).
5. On the front panel of the Servo Series, turn both Channel input controls fully counterclockwise (to
their “MIN”setting). Then connect the supplied heavy-gauge 3-pin “IEC”cable to the rear panel IEC
connector and to any grounded AC socket.
Input connectors
Because of the relay protection circuitry built into the Servo Series, you can even plug it into the
same power strip that other audio devices (such as a mixing console) are connected to. You can then
turn on all devices at once with the single power strip on-off switch, with no danger of damaging
connected speakers by generating “thumps.”
6. Press the front panel Power switch in order to turn on the Servo Series. The Power LED will light
and the Protection LED will go on. After approximately five seconds, the Protection LED will go off
(you’ll hear a click when this occurs).
Channel Input control
7. Apply an input signal to the Servo Series at or about +4dBu (if sending signal from a mixer, drive
the output meters at approximately 0 vu). While the input signal is present, slowly raise the Channel
Input controls until the desired sound level is achieved. The SIGNAL and PEAK LED indicators next to
each Channel input control will show you the continuous power output of the Servo Series as signal
is being passed. For the best signal-to-noise ratio, the Servo Series should normally be run with the
Channel Input controls at or near maximum (fully clockwise, at the “MAX”position) and the PEAK
segments should light occasionally (but not frequently) during peak levels. If you are using a mixer
that has a master output level control (sometimes called “control room level”), use it to attenuate the
signal as necessary to achieve the desired speaker level.
If you encounter difficulty with any aspect of setting up or using your Servo Series, contact your lo-
cal Samson dealer. If purchased in the United States, you can call Samson Technical Support (1-800-
372-6766) between 9 AM and 5 PM EST
Three-segment LED meter
6
The Servo Series Protection Circuitry
As noted in the “Guided Tour”section of this manual, the Servo Series front-panel
Protection LED indicates the activity of the relay speaker connection circuitry. When
the Protection LED is lit, this circuitry is active, and all connected speakers are muted
(provided with no signal), thus protecting them and preventing any audible “thump”
from occurring.
The following conditions will cause the Protection LED to go on:
• Initial power-up: For approximately five seconds after initial power-up, the protec-
tion circuitry is activated and the speaker outputs are muted. If everything is operat-
ing normally, you will hear an audible click at the conclusion of this brief period, as
the protection circuitry is deactivated and the Servo Series begins delivering signal to
connected speakers (at which point you’ll hear a click). It is normal for the Protection
LED to fade gradually after the amplifier is powered off.
Overheating: A temperature sensing device in the Servo Series will cause the protec-
tion circuitry to be activated (and the Protection LED to go on) whenever the operat-
ing temperature of the unit rises above a safe level. To guard against this problem,
make sure the Servo Series receives adequate ventilation on all sides and that both
the front and rear panels are unobstructed.
• Severe overcurrent conditions: This occurs whenever the signal being output from the
Servo Series rises to a level above 20% THD (Total Harmonic Distortion).
• Shorted speaker cables: This will occur if, due to faulty wiring, the hot and ground sig-
nals being output by the Servo Series are shorted to one another.
• Output impedance drops below 4 ohms: This can occur if the Servo Series is connect-
ed to inappropriate speaker systems (see the “Setting Up and Using Your Servo Series”
section on page 6 in this manual for more information).
• DC voltage detected at speaker output: The most likely cause of this is an internal fail-
ure.
In general, any time the Protection LED lights up (other than during the approxi-
mately five seconds following initial power-up), there is reason to be concerned. If this
occurs, turn the Servo Series off immediately and carefully check all wiring and exter-
nal devices in order to locate and correct the condition that caused the LED to light up
in the first place.
For further assistance, contact your local Samson dealer. If purchased in the United
States, you can call Samson Technical Support (1-800-372-6766) between 9 AM and 5
PM EST.
7
Bridge Mode
The Servo Series provides a rear-panel switch that allows it to be used in either Stereo
or Bridge mode. When this switch is placed in the “STEREO” (down) position, the
Servo Series functions as a true stereo amplifier, where both of the two independent
amplifier channels (Channel 1 and Channel 2) can receive different input signals and
produce independent output signals. However, when the switch is placed in the
“BRIDGE”(up) position, the Channel 1 input signal is routed to both power amplifiers
bridged together, producing a single output signal of 200 watts for the Servo 200, 300
watts for the Servo 300, and 600 watts for the Servo 600.
The illustration on the right shows how this works. In Bridged mode, the polarity
(phase) of the Channel 2 output signal is reversed relative to that of the Channel 1 out-
put signal. Both channels then process the same input signal, with the speaker load
connected so that power is derived from both channels. The effective voltage swing
seen by the load is thus doubled, so that the power output is multiplied by more than
Bridge Mode
When using the Servo Series in Bridge mode, be sure to connect your loudspeaker
as shown in the illustrations on page 9 (and as silkscreened on the rear panel), with
the red (+) terminal of the Channel 1 output connected to the positive input of the
speaker and the red (+) terminal of the Channel 2 output connected to the negative
input of the speaker.
Do not use the black ground (-) output terminal of either channel (the speaker
load must “float” away from the amplifier chassis).
See pages 9 in this manual for interconnection diagrams when using the Servo Series
in Bridge mode.
The illustrations on this page show the required
interconnections when using the Servo Series in
Stereo and Bridged modes.
Stereo Mode: (two or four speakers)
������
������
������
P2
�������
�������
�������
�������
MPL2242
�������
-
+
+
-
-
+
+
-
-
+
+ +
+
-
-
-
(4 ohm min)
(4 ohm min)
(4 ohm min)
(4 ohm min)
(8 ohm min)
(8 ohm min) (8 ohm min) (8 ohm min)
Bridged Mode: (single speaker only)
9
Specifications
Bridged mono
Signal to Noise Ratio (20Hz-20k)
Distortion(SMPTE-IM)
Input sensitivity @8ohms
102dB
0.05%
1.24V(4dBu)
32dB
102dB
0.01%
1.24V(4dBu)
33dB
104dB
0.04%
1.24V(4dBu)
34dB
Voltage Gain
Output Circuitry
AB
AB
AB
AC Power @1/8 rated power 4ohms, max.
AC Power @1/3 rated power 4ohms, max.
AC Power @ rated power 4ohms, max.
Distortion(typical @4 ohms)
20Hz-20kHz,10dB below rated power
IkHz,rated power
0.5A
1.1A
3.3A
0.7A
1.7A
5.0A
1.3A
3.3A
10A
0.01%
0.1%
0.01%
0.1%
0.03%
0.1%
Frequency Response @8ohms 1Watt
0/-0.5dB:20Hz-20kHz,0/-3dB:5Hz-60kHz
Damping Factor(400Hz)
Input Impedance
Input Clipping
Cooling
280 280 350
15kohm Unbalanced,30kohm Balanced
10Vrms(22dBu)
Continuously variable speed, fan forced air
Connectors (each channel)
Input:
Output:
RCA unbalanced and1/4”(6.3mm)TRS, balanced
5-way Binding post and 1/4”Phone
Controls
AC power switch,Channel 1 and 2 volume
Indicators
Power on(blue),Protection(amber)
Signal(green) for each Ch.,Peak(red) for each Ch.
Level: , -24 dB, -20 dB, -16 dB, -12 dB, -8 dB, -4 dB, -2 dB. O, +2 dB and +4 dB
(PEAK).
Protection
Short circuit,Thermal,Current limit,DC offset,Current inrush,RF
protection, Turn on/Turn off muting
Power Requirements
Dimensions(WXHXD)
Net Weight
115/230,240VAC,50/60Hz
19”(483mm)X3.5”(89mm)X11.7”(297mm)
15 lbs 6.82 kg 20 lbs 9.09 kg
24 lbs 10.91 kg
10
Appendix A: Power Output vs. THD
Servo 600
1
125
120
115
110
105
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0.95
0.9
0.85
0.8
0.75
0.7
0.65
0.6
0.55
0.5
THD %
�����
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
0
10
20
50
100
200
500
1k
2k
5k
10k
20k
50k
������������
Appendix B: Frequency Response
AUDIO PRECISION Servo 600 LEVEL (dBr) vs FREQ (Hz)
0dB ref
5.0000
4.0000
3.0000
2.0000
1.0000
0.0
Ap
-1.000
-2.000
-3.000
-4.000
-5.000
10
100
1k
10k
50k
Linearity (0 dB Ref) vs. Frequency sweep
10 Hz - 50 kHz Typical for all Servo models
12
Samson Technologies Corp.
575 Underhill Blvd.
Syosset, NY 11791-9031
Phone: 1-800-3-SAMSON (1-800-372-6766)
|