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PURPOSE AND FUNCTION 

The ST55.2 is a compact, very efficient, two channel power amplifier. It is designed for use in all types of audio or 
audio/video systems. The term versatile is almost adequate to describe the variance of operational modes the 
ST55.2 is capable of providing. This is all accomplished through the simple placement of internal jumpers and the 
paralleling or bridging of its outputs and/or linking multiple ST55.2’s. 
 

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

 

• 

The most obvious function for the ST55.2 is to take 2 separate audio inputs, such as a stereo 
pair, and provide 2 separate amplified outputs. Your ST55.2 has arrived set up in this 
configuration. 

 

• 

With the inputs buffered, a line output (OUT BUS) may be taken from 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 ST55.2 may be used mono to provide one, medium current channel 
in order to drive a speaker requiring more power. 

 

• 

As a result of the ST55.2’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.

 

 

 

 

DESIGN AND CONSTRUCTION 

The ST55.2 utilizes high quality electronic circuitry to achieve an environment wherein a detailed, transparent, 
and highly musical sound can be realized. The high quality complement of parts, include state-of-the-art solid-
state devices, 1% metal film resistors, computer grade electrolytic power supply capacitors, and a high capacity 
toroidal transformer. 
 
 

FEATURES 

Toroidal Transformer

 - Efficient high current transformer for improved dynamics. 

 

Discrete Circuitry

 - More accurate and three dimensional reproduction of source material. 

 

Limited Protection

 - Provides short term protection from accidental shorting of output devices and protection 

from thermal overload. 
 

Gold Plated Connectors

 - Improve connections for better sound and minimized signal loss and degradation. 

 

1% Metal Film Resistors

 - Low noise resistors for better sound and a greater degree of repeatability. 

 

Medium Current

 - Ability to reproduce demanding recordings. 

 

Computer Grade Capacitors

 - Large capacity computer grade electrolytic capacitors for extended low frequency 

control and improved dynamics. 
 
 
 
 
 
 
 
 
 
 
 
 

Summary of Contents for ST55.2

Page 1: ...P N13436 0702 B K S B IMPLY ETTER B K Components Ltd ST55 2 OWNER S MANUAL ...

Page 2: ...ii B K Components Ltd 2100 Old Union Road Buffalo New York 14227 2725 Phone 1 800 543 5252 or 716 656 0026 Fax 716 656 1291 E mail info bkcomp com Web www bkcomp com ...

Page 3: ...l 3 Control Muting 4 Level Controls 5 Inputs 5 Outputs 5 Internal Bus Structure 6 Jumper Description 7 Mono Application Medium Current 7 Bridged Application High Voltage 8 System Installation 9 Making the Connection 9 Troubleshooting 10 Care and Cleaning 10 Specifications 11 Limited Warranty 12 Returning Equipment 12 WWW BKCOMP COM 13 ...

Page 4: ...ace 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 amplif...

Page 5: ...us 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 DESIGN AND CONSTRUCTION The ST55 2 utilizes high quality electronic circuitry to achieve an environment wherein a detailed transparent and highly musical sound can be realized The high quality complement of parts include sta...

Page 6: ...S PLUS PLUS MINUS RIGHT LEFT LEVEL CONTROLS B K Components Ltd Made in the U S A B K Components Ltd Made in the U S A www bkcomp com AC LINE 2 1 3 7 6 5 4 1 AC fuse holder Holds the AC Line fuse This fuse is an 8 Amp 250 Volt Slow Blow fuse Replace with same type and value fuse only 2 AC Input receptacle For attaching the supplied AC power cord to the amplifier 3 Speaker outputs For connecting the...

Page 7: ...AL IS APPLIED TO CTRL IN WHEN SWITCH IS SET TO ENABLE THE AMPLIFIER WILL ONLY OPERATE WHILE A 5 24VDC SIGNAL IS APPLIED TO CTRL IN DEFEAT CTRL IN ENABLE CTRL IN ENABLE CONTROL I O CTRL OUT CTRL OUT 12VDC 125mA 12VDC 125mA CTRL IN CTRL IN WHEN SWITCH IS SET TO ENABLE THE AMPLIFIER WILL ONLY OPERATE WHILE A 5 24VDC SIGNAL IS APPLIED TO CTRL IN WHEN SWITCH IS SET TO ENABLE THE AMPLIFIER WILL ONLY OPE...

Page 8: ...nnectors one for each channel which may be used to connect the amplifier to the preamplifier RCA connector Here is a typical input setup BUS INPUT LEFT RIGHT LEFT RIGHT MONO BUS OUTPUT R M L L From Left Output Of Preamplifier From Right Output Of Preamplifier Left Channel Output to Another Amplifier R Right Channel Output to Another Amplifier Left Right Mono Channel Output to Another Amplifier You...

Page 9: ...ations If you wish to use the amplifier as a stereo two channel amplifier you need not change any of the settings In order to reconfigure the ST55 2 s channels remove the source control group jumper from its present position if necessary and install it on the terminal you wish to select as the source for that channel Make sure it has been inserted on both terminal pins of the jumper modules To com...

Page 10: ... USE VOL location The USE VOL setting SHOULD NOT be used when channels are bridged or combined Invert Jumper module This is a single jumper module that is set apart up and to the right from the channel jumper modules on the circuit board It provides a special function when the jumper is set on the L pins the left bus signal feeding the left channel will be inverted Note A jumper MUST be installed ...

Page 11: ...L terminal Finally connect the speakers to the right channels terminal and the speakers to the left channels terminal Input your source signal into the left channel input only the left channel may be used for bridging Note The default position for this jumper plug is set to the L terminal The jumper plug must be installed at this location at all times when not using the L invert function MINUS PLU...

Page 12: ...t is recommended that you locate a separate AC power outlet for the amplifier one that is not shared by any other audio component in the system or any other household component This will eliminate the possibility of the amplifier modulating the power being supplied to the component and compromising the signal originating from that component Locate the AC power cord provided with the amplifier and ...

Page 13: ... Speakers connected out of phase 1 Check all connections making sure that cables are connected to and to Loud hum or buzz on one or more channels 1 Poor ground connection in inter connect cables 1 Check all connectors and repair as necessary Channel sounds distorted and low output 1 Blown rail fuse 1 Replace blown rail fuse inside amplifier Note If unit continues to blow power inlet fuses DO NOT U...

Page 14: ... ohms Damping factor 100 Current peak to peak 20 Amps Slew rate 14 V sec Dynamic headroom 1 4 dB S N A weighted 95 dB Voltage gain 28 Line voltage 120 220 240 VAC switchable Dimensions O A 17 w X 12 d X 3 75 h Weight 23 lbs max Power consumption 210 watts max 2 3 Amps max current draw 15 watts no input Replacement fuses Line 8 Amp 250 Volt Slow Blow Rails 4 Amp 250 Volt T Lag ...

Page 15: ...ades B K delivers exceptional value to its customers But what is Upgradability Upgradability is not a guarantee we define it as a philosophy of designing and manufacturing products so that as audio technology evolves B K can provide enhancements and improvements to its products that are economically viable THE EXPRESS FACTORY WARRANTY HEREIN CONTAINED IS IN LIEU OF ANY AND ALL OTHER WARRANTIES EXP...

Page 16: ...13 WWW BKCOMP COM B K Components Ltd 2100 Old Union Road Buffalo New York 14227 Phone 716 656 0026 ...

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