B and K ST-125.1 Owners manual

B&K

SB!IMPLY ETTER

B&K Components, Ltd.

ST125.3

ST125.2

P/N13437 0702

ST125.1

Owner’s Manual

B&K Components, Ltd., 2100 Old Union Road, Buffalo New York 14227-2725

Phone [phone] or [phone], Fax [phone]

E-mail: [e-mail] Web: www.bkcomp.com

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TABLE OF CONTENTS

Table of Contents ....................................................................................................................................................iii

Safety Precautions .................................................................................................................................................. 1

Purpose and Function............................................................................................................................................. 2

Design and Construction ....................................................................................................................................... 2

Features.................................................................................................................................................................... 2

Rear Panel ................................................................................................................................................................ 3

Level Adjustment..................................................................................................................................................... 4

Inputs ........................................................................................................................................................................ 4

XLR Balanced ....................................................................................................................................................... 4

RCA Unbalanced................................................................................................................................................... 4

Balanced or Unbalanced Connections.................................................................................................................. 5

Outputs ..................................................................................................................................................................... 6

System Installation.................................................................................................................................................. 7

Making the Connection ........................................................................................................................................... 7

Control Input and Output........................................................................................................................................ 8

Troubleshooting ...................................................................................................................................................... 9

Care and Cleaning ................................................................................................................................................... 9

Specifications ........................................................................................................................................................ 10

Limited Warranty ................................................................................................................................................. 11

Returning Equipment........................................................................................................................................... 11

Rear Panel Enlarged Veiw .................................................................................................................................... 12

WWW.BKCOMP.COM ............................................................................................................................................ 13

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SAFETY PRECAUTIONS

PLEASE READ BEFORE INSTALLING

WARNING: to prevent fire or shock hazard, do not expose this unit to rain or moisture. Care should be
taken to prevent objects or liquid from entering the enclosure. Never handle the power cord with wet
hands.

• The lightning flash with arrowhead, within an equilateral triangle, is intended to alert the user of the
presence of uninsulated “dangerous voltage
electric shock to you.

” within the product’s enclosure that may constitute a risk of

• The exclamation point within an equilateral triangle is intended to alert the user of the presence of
important operating and maintenance (servicing) instructions in the literature accompanying the unit.

• Caution: To prevent the risk of electric shock, do not remove cover. No user-serviceable parts inside.
Refer servicing to qualified service personnel.

• Unplug the amplifier from the AC outlet when plugging in or unplugging cables, when left unused for an
extended period of time, moving the amplifier, or when you suspect lightning in your area.

• Prevent damage to the power cord. Do not bend, pull, place objects on, alter, etc. Replace the power cord
if it becomes damaged. Always grasp the plug on the power cord when plugging in or unplugging the
amplifier from the AC outlet.

• Your system may produce sound levels capable of causing permanent hearing loss. Do not operate for
extended periods of time at high volume levels.

• Make sure the amplifier is placed on a level surface.

• The amplifier is equipped with raised feet to provide ventilation, reduce acoustic feedback, and provide

protection against scratching the surface the unit is resting on. We advise against removing or altering
feet.

• Do not stack anything on top of the amplifier (processor, source, etc.) Leave a minimum of 2” clearance
from the top of the amplifier to the next shelf (or component) to insure proper ventilation.

• The amplifier should be located away from other sources that may be sensitive to heat.

• Do not perform any internal modifications to the amplifier.

• Always connect the amplifier’s power cord to an unswitched AC outlet for normal operation.

• If young children are present, adult supervision should be provided until the children are capable of

following all rules for safe operation.

• Do not plug the amplifier’s power cord into an outlet with an unreasonable number of other devices. Be
careful if using extension cords and ensure the total power used by all devices does not exceed the
power rating (watts/amperes) of the extension cord. Excessive loads may cause the insulation on the
cord to heat and possibly melt.

• Mistaking CONTROL OUTPUT or CONTROL INPUT connectors for audio/video inputs or outputs may
damage your amplifier or other components.

• Damage can occur to your speakers if the power rating of each individual driver is exceeded by the
amplifier. Ensure that all the drivers in your system are capable of handling not only the average power
being delivered by the amplifiers, but also the peak power that is likely to be generated during strong
passages. If you are unsure of your speaker's power rating, contact the speaker manufacturer or the
dealer where you purchased them.

• The amplifier should be serviced by qualified personnel when:

A. The amplifier is not functioning properly.
B. Objects have entered the chassis.
C. The amplifier was exposed to rain or other type of moisture.
D. The amplifier was dropped, or the chassis is damaged.

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PURPOSE AND FUNCTION

The ST125.3 (three channel), ST125.2 (two channel) and ST125.1 (mono) are high power amplifiers that are
designed for use in all types of audio or audio/video systems.

DESIGN AND CONSTRUCTION

The ST125.3, ST125.2 and ST125.1 amplifiers utilize high quality electronic circuitry to achieve an environment
wherein a detailed, transparent, and highly musical sound can be realized. The high quality parts complement
includes: state-of-the-art solid state devices, 1% metal film resistors, computer grade electrolytic power supply
capacitors, and a high capacity toroidal transformer.

The ST125.3, ST125.2 and ST125.1 operate with a class A predriver and AB MOSFET power output stages.
These high power amplifiers are capable of delivering their full rater power while reproducing the most demanding
music passages effortlessly into the most demanding audiophile speakers.

FEATURES

Control Output - one 3.5 mm 12 VDC @ 125 mA output for turning on amplifiers and controlling external

systems such as a projection screen or B & K amplifier.

Control Input - one 3.5 mm jack that allows standby on/off with a 5-24 VDC control signal.

Gold Plated Connectors - better sound with minimum signal loss and degradation.

Toroidal Transformer - Efficient, high current, shielded transformer that supplies the amplifier with a clean and

constant supply of power, even during highly demanding source material passages.

Discrete Circuitry - Dynamically provides a full, accurate, and three dimensional reproduction of source material.

Class A Predriver - Improves low level detail and clarity for smoother, more musical sound.

AB MOSFET Output Stage - Provides efficient and linear power delivery, as well as protection from thermal

overload.

1% Metal Film Resistors - Higher quality resistors for lower noise, better sound, and a greater degree of

repeatability.

High Current - Ability to cleanly, accurately, and reliably reproduce demanding recordings or source materials

into low impedance drivers and speaker systems.

Computer Grade Capacitors - Large capacity computer grade electrolytic capacitors for extended low frequency

control, increased power supply, and improved dynamics.

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