ST260 Two Channel Amplifier OWNER'S MANUAL B & K Components Ltd. 12997 REV 050500 B&K Components, Ltd., 2100 Old Union Road, Buffalo, New York 14227 Table of contents Safety Precautions Purpose and function Design and construction Features Rear panel view Rear panel description Control muting Level controls Inputs Outputs Internal Bus Jumper description Mono application Bridged application System installation Making the connection Troubleshooting Care and cleaning Specifications Warranty Accessories included: Manual and Power cord Page 2 Page 3 Page 3 Page 4 Page 4 Page 5 Page 5 - 6 Page 6 Page 7 Page 8 Page 9 Page 9 - 10 Page 11 Page 12 Page 13 Page 13 - 14 Page 15 Page 15 Page 16 Page 17 Page 1 SAFETY PRECAUTIONS PLEASE READ BEFORE INSTALLING 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 ST260 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 alter or remove them. 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 ST260's purpose and function The ST260 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 ST260 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 ST260's. Here is a listing for some of the many tasks it can be set up to perform: & The most obvious function for the ST260 is to take 2 separate audio inputs, such as a stereo pair, and provide 2 separate amplified outputs. Your ST260 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 ST260 may be used mono to provide one, medium current channel in order to drive a speaker requiring more power. As a result of the ST260'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 ST260 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 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. Rear Panel View )LJXUH$ 1. AC fuse holder 2. AC Input receptacle 3. Speaker outputs 4. Amplifier control muting input/output 5. Line Level outputs 6. RCA inputs 7. Level controls Page 4 Rear panel description 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 speakers to the amplifier. Explained further on page 8. 4. Amplifier control muting input/output To provide remote switching of mute on/off of the amplifier. Explained further on page 5. 5. Line level outputs 6. RCA inputs For connecting signal to another amplifier (daisy chaining). For connecting signal patch cables (interconnects) from the preamplifier to the amplifier to pass signal. For adjusting the input level to the amplifier. Explained further on page 6. 7.Level controls - Control muting A control is provided on each ST260 amplifier to allow remote switching of mute on/off. The preamplifier's control output, such as is provided with B&K series preamplifiers, can be utilized to provide a control signal to the ST260. If more than one amplifier is being controlled, the control signal can be extended to include each successive unit by simply running an RCA type audio cable from the CTRL OUT connector of the first amplifier to the CTRL IN connector of the next unit (commonly referred to as `daisy chaining'). An example of how to connect two amplifiers is illustrated in figure B. If a source other than a B&K series preamplifier is used to control multiple amplifiers, only the control output voltage from the source is critical. It must be within the range, as indicated on the rear panel, 5-24 volts DC is required. The amplifier will provide each successive amplifier with a control voltage of 12 volts DC for reliable operation. The amplifiers control output may be used as a source of 12 VDC @ 125 mA for other user applications as well. DO NOT POWER MOTORS WITH THIS CIRCUIT. Page 5 )LJXUH% If the control function is desired, each unit in the system must remain connected at all times and the control must be enabled. To enable the control function, the CTRL ENABLE button must be out for each controllable amplifier in the system. For more information on the amplifiers output status under various control conditions, refer to the table below. @ CTRL IN Signal Signal No Signal No Signal Button position OUT IN OUT IN Output status Sound Sound Mute Sound @ CTRL OUT Signal Signal No Signal Signal *Note: The control voltage is for muting control only. Each amplifier must be connected to its own source of AC power in order for it to operate. Level controls There are two level controls on the back of the amplifier. One level control for each channel. When using the level controls, first start with them turned all the way up (clockwise). Then adjust them according to your system requirements to match the sound level coming from each speaker. This is a rough adjustment for matching different driver impedances. Any fine tuning should be done by the preamplifier. Page 6 Example: When using 4 ohm and 8 ohm speakers together, the 4 ohm may sound louder then 8 ohm at a given volume level. The level controls on the amplifier are used to match the speakers volume level. Clockwise will increase the output. Counter clockwise will decrease the output. )LJXUH& Inputs RCA type connectors accept line input from the preamplifier's unbalanced output connectors. There are two input connectors, one for each channel, that may be used to connect the amplifier to the preamplifier. RCA cable connector - Here is a typical input setup: )LJXUH' You will notice the OUT BUS connections shown above. You may use these to connect to another amplifier. The L BUS OUT carries the same signal as the L INPUT. The R BUS OUT carries the same signal as the R INPUT. The L+R BUS OUT carries the combined signal from the left and right inputs. Page 7 Outputs Five way binding posts are provided. One pair for each channel. They are designed to accept a banana-type plug or spade lug connector (shown below) and are color coded for easy identification. The red (+) post should always be connected to the speakers (+) jack. The black (-) post should always be connected to the speakers (-) jack. Spade connector Banana jack Here is a typical amplifier setup: )LJXUH( Page 8 ST260's internal bus structure In order to gain access to the internal bus structure, you must first remove the top cover. Turn the amplifier so the rear panel is facing your. The jumper modules may be seen on the circuit board just behind the level controls. Below is the default setup for the ST260 amplifier. By arranging the jumpers allows you to configure the amplifier for different applications. If you wish to use the amplifier as a stereo (two channel) amplifier, you need not change any of the settings. )LJXUH) In order to reconfigure the ST260'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 complete the configuration, the volume group jumper should be placed at either the `USE VOL' or `NO VOL' terminal depending on you configuration. Note: A channel that is not being used in your configuration should have its jumper plugs installed at the default position as shown in Figure F. Jumper description Figure G illustrates the jumper modules used in configuring each channel. Each jumper terminal location is conveniently labeled as to the source it can be configured to provide. Explained further on the following page. )LJXUH* Page 9 R BUS - Along with being the right channel input, it is used as the input to the right bus and the right source for the `L+R BUS'. Because it is a BUS input, any signal input here will appear at the `R BUS' jumper terminal for both of the ST260's jumper modules. L+R BUS - Installing a jumper plug at this terminal on either of the two internal jumper modules selects the combined signal being carried by both the left and right inputs. If the left bus and right bus are being used to carry stereo right and left channels, a jumper plug installed at the `L+R BUS' location will provide a true L+R mono output. L BUS Along with being the left channel input, it is used as the input to the left bus and the left source for the `L+R BUS'. Because it is a BUS input, any signal input here will appear at the `L BUS' jumper terminal for both of the ST260's jumper modules. NO VOL - If volume control is desired only from the source, or if outputs are being combined to obtain higher power, the jumper plug should be installed at the `NO VOL' location. USE VOL - If volume control is desired at the amplifier, beyond that provided at the source, a shorting plug is installed at the `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 at L BUS, R BUS, or L+R BUS, AND a jumper MUST be installed at NO VOL or USE VOL for the amplifier to operate. Page 10 Mono application (Medium current) The ST260's two output channels may be paralleled (mono) to combine the left and right channels output current. This feature allows the amplifier to double its apparent output current. To use, place the source group jumper for both channels on the `L BUS' jumper terminal. Place the volume group jumper for both channels on the `NO VOL' jumper terminal. )LJXUH+ The speaker output terminals on the ST260's rear panel must be paralleled in order to complete the setup. Simply connect the (+) terminals for both channels together using a jumper wire (not supplied with th ...