Samson SA120A User manual

OWNERS MANUAL

STUDIO

AMPLIFIER

SERVO 120

®

Introduction 3
Servo 120 Features 4
Guided Tour 5

Front Panel 5
Rear Panel 6

Setting Up and Using the Servo 120 Amplifier 7
The Servo 120 Protection Circuitry 8
Bridge Mode 9
Appendix A: Linearity vs. Frequency Sweep 10
Appendix B: Power Output vs. THD 11
Specifications 12

3

Congratulations on purchasing the Samson Servo 120 Power Amplifier! Although designed for easy
operation, we suggest you first take some time to go through these pages so you can fully understand
how we’ve implemented a number of unique features.

The Servo 120 is a single rack-space stereo power amplifier which is optimized for use in both
professional and project recording studio environments as well as for live performance. It delivers
60 watts of power per channel into 4 ohms (or, in Bridge mode, 120 watts into 8-ohms) over the full
frequency spectrum, from 3 Hz to 65 kHz. Both balanced 1/4" TRS and unbalanced RCA-type input
connectors are provided, along with push-spring terminal outputs. Front-panel controls and displays
include a power switch, independent left- and right-channel input level controls, five-segment LED
meters, a Protection LED, and a convenient headphone jack and speaker on/off switch for private cue
monitoring. Suggested applications for the Servo120 include:

•

Amplification for nearfield monitors or cue headphones in both professional and project studios ­Its superb audio specs and whisper-quiet performance (its convection cooling design means there is
no fan), along with its unique front-panel speaker on-off switch and dedicated headphone jack, make
the Servo 120 the perfect complement to any recording studio.

•

Home Theatre applications - The power and flexibility offered by the Servo 120 (it can be used either
as a 60 watt stereo amplifier, or, in bridge mode, as a 120 watt monophonic amp) makes it the
perfect addition to any home theatre, in conjunction with any DVD player or other surround sound
system. For example, use it in stereo mode to drive your main front left/right speakers, using your
home stereo to drive the satellite rear speakers—or use the Servo 120 in Bridge mode to drive your
center channel or subwoofer with power galore.

•

As an extension to a home hi-fi system - The Servo 120 boasts professional specs which far exceed
that of most consumer products. For a real “studio” experience in your own home, try connecting
your home hi-fi amplifier’s auxiliary outputs to the Servo 120’s inputs (thus using your hi-fi amp as a
preamplifier) and then connect your existing speakers to the Servo 120’s outputs. If you fall in love
with the sound (as we’re sure you will), you might want to substitute a professional pre-amplifier for
your existing hi-fi amp—and, from there, you may well end up graduating to higher-level speakers.
High quality sound is addicting—don’t say we didn’t warn you!

•

Powering public address systems in permanent installations - The Servo 120 can be used to
effectively drive PA speakers in installations such as classrooms and corporate conference rooms.

•

Onstage monitoring - In small and medium-sized onstage areas (such as in clubs, lounges, etc.), the
Servo 120 can be used to drive stage monitors, allowing the performers to hear themselves without
having to rely on onstage equipment amplification.

•

MIDI rack monitoring - Taking only a single rack space, MIDI musicians can easily incorporate the
Servo 120 into their existing rack of gear. Combined with a pair of high quality stage or studio
speakers, this makes for an excellent monitoring system that can accurately reproduce the broad
range of frequencies typically output by devices such as synthesizers, samplers, and digital audio
workstations.

In these pages, you’ll find a detailed description of the many features of the Servo 120 Power Amplifier,
as well as a guided tour through its front and rear panels, step-by-step instructions for its setup and use,
reference appendices, 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 unit ever require servicing, a

Return Authorization number (RA) is
necessary. Without this number, the unit will not be accepted. Please call Samson at 1-800-372-6766
for a Return Authorization number prior to shipping your unit. Please retain the original packing materials
and, if possible, return the unit in its original carton and packing materials.

Introduction

4

Servo 120 Features

The Samson Servo 120 Power Amplifier utilizes the latest technology in professional power amplifier
design. Here are some of its main features:

• Power to spare - Each channel delivers 60 watts of power into 4 ohms (or, in Bridge mode, 120 watts
into 8 ohms).

• Clean, crisp sound - Impressive audio specifications such as .01% THD, S/N of 105 dB, crosstalk of
75 dB, and frequency response of 3 Hz to 65 kHz guarantee ultra-clean sound quality in any live or
recording environment.

• Independent input level controls for each channel with 41-position detents.

• Five-segment LED meters for each channel continuously display power output levels and allow you

to correct for overloading (clipping) conditions.

• Front-panel Protection LED shows you at a glance overheating or faulty wiring conditions.

• Innovative front-panel Speaker on/off switch and dedicated headphone jack enables private cue

monitoring of the input signal.

• Both electronically balanced 1/4" TRS and unbalanced RCA-type input connector jacks are provided,
along with push-spring terminal output connectors.

• Convection cooling (no fan) makes for whisper-quiet operation even in critical listening environments
such as recording studios.

• Unique bipolar circuit design that continuously keeps DC output during idling at or near 0 volts (thus
keeping idle speakers at their 0 point). This serves to minimize heat overload problems by effectively
preventing the Servo 120 from applying power when unnecessary.

• Protection relay circuitry (linked to the DC offset circuitry) that prevents “thumps” when powering on
or off. This means that you can use the Servo 120 with a single power strip into which a mixer or
other audio devices are connected, without danger of damage to connected speakers.

• Toroidal transformer power supply.

• Rugged construction (an all-steel chassis with a titanium finish and a lightweight anodized aluminum

heat sink) makes the Servo 120 eminently roadworthy.

• Flexible design allows the Servo 120 to be used free-standing or, with the use of included rack ears,
mounted in any standard 19" rack (taking just a single rack space).

• Three-year warranty.

• Last but certainly not least, value. The Samson Servo 120 has been designed from the ground up to

deliver excellent yet affordable sound quality.