B and K ST-120 Mk2 Owners manual

B & K Components Ltd.

P/N 12687

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

Safety Precautions Page 2
Purpose and function Page 3
Design and construction Page 3
Features Page 4
Rear panel view Page 4
Rear panel description Page 5

Control muting Page 5 - 6
Level controls Page 6
Inputs Page 7

Outputs Page 8
Internal Bus Page 9
Jumper description Page 9 - 10
Mono application Page 11
Bridged application Page 12
System installation Page 13
Making the connection Page 13 - 14
Troubleshooting Page 15
Care and cleaning Page 15
Specifications Page 16
Warranty Page 17

Manual and Power cord

Page 1

WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS UNIT
TO RAIN OR MOISTURE.

The lightning flash with arrowhead, within an equilateral triangle, is intended to alert the
user of the presence of uninsulated “dangerous voltage” within the product’s enclosure
that may be sufficient magnitude to constitute a risk of electric shock to you.

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.

 Observance of polarity is essential. Double-check connections before turning

the amplifier on. The amplifier can be damaged if polarities are incorrect.
 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 speaker system

are capable of handling not only the power being delivered by the amplifier, but

the energy that is likely to be generated during strong passages.

 Turn amplifier ‘off’ when plugging in or unplugging input and speaker cables!!!
 The ST1200 series II is equipped with raised feet so that continuous ventilation

can be maintained. They help to maintain acoustic feedback into the amplifier at

a minimum. They also provide a measure of protection against scratching any

surface the unit might be resting on.
 Do not stack anything on top of the amplifier (preamplifier, processor,

source...etc.).
 Leave at least 2-3 inches clearance from the top of the amplifier to the next shelf,

component, etc., to ensure proper ventilation.

* If you are at all unsure of what the speaker ‘ratings’ are, contact your dealer.

Page 2

The ST1200 series II is a compact, very efficient, two channel power amplifier. It is
designed to be used in all types of audio or audio/video systems. The term versatile is
almost adequate to describe the variance of operational modes the ST1200 series II is
capable of providing. This is all accomplished through the simple placement of internal
jumpers and the paralleling or bridging of it’s outputs and/or linking multiple ST1200
series II’s.

Here is a listing for some of the many tasks it can be set up to perform:

& The most obvious function for the ST1200 series II is to take 2 separate

audio inputs, such as a stereo pair, and provide 2 separate amplified
outputs. Your ST1200 series II has arrived set up in this configuration.

& With the inputs buffered, a line output (OUT BUS) may be taken from

either the L BUS, R BUS, or L+R BUS and sent on to another amplifier.
This allows for linking of multiple amplifiers.

& Continuing its versatility, the ST1200 series II may be used mono to

provide one, medium current channel in order to drive a speaker requiring
more power.

& As a result of the ST1200 series II’s unique bus system, the input to the

left channel may be inverted thereby allowing the possibility of creating a
single high voltage (bridged) channel from one source, through the left
bus.

The ST1200 series II utilizes high quality electronic circuitry to achieve an environment
wherein a detailed, transparent, and highly musical sound can be realized. The high
quality parts complement include state-of-the-art solid state devices, 1% metal film
resistors, computer grade electrolytic power supply capacitors, and a high capacity
toroidal transformer.

Page 3

- Efficient high current transformer for improved dynamics.

- More accurate and three dimensional reproduction of source

material.

- Provides short term protection from accidental shorting of output

devices and protection from thermal overload.

- Improve connections for better sound and minimized signal

loss and degradation.

- Low noise resistors for better sound and a greater degree

of repeatability.

- Ability to reproduce demanding recordings.

- Large capacity computer grade electrolytic capacitors

for extended low frequency control and improved dynamics.

1. AC fuse holder 5. Line Level outputs

2. AC Input receptacle 6. RCA inputs

3. Speaker outputs 7. Level controls

4. Amplifier control muting input/output

Page 4