Reference 7250/7260
series II
Five/Six Channel Amplifier
OWNER’S MANUAL
B & K Components Ltd.
P/N 13007 Rev.0004
Table of contents
Safety Precautions
Purpose and function
Design and construction
Features
page 2
page 3
page 3
page 3
Rear panel view
Rear panel description
Level controls
page 4
page 4 - 6
page 5
Inputs
page 5 - 6
page 6
Outputs
Control Muting
page 8 - 9
page 7
System installation
Making the connection
Troubleshooting
Care and cleaning
Specifications
page 7 - 8
page 10
page 10
page 11
page 12
Warranty
Accessories included: Manual and Power cord
Page 1
P/N 13007 Rev.0004
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.
Ÿ
Ÿ
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. Make sure 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.
Ÿ
Ÿ
Turn amplifier ‘off’ before plugging in or unplugging input and speaker cables!!!
The Reference 7250/7260 series II is equipped with raised feet so that continuous
ventilation can be maintained. They help to keep 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.
Ÿ
Ÿ
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 insure proper ventilation.
* If you are at all unsure of what the speaker ‘ratings’ are, contact your dealer.
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P/N 13007 Rev.0004
The Reference 7250/7260 series II purpose and function
The Reference 7250/7260 series II is a high current, five/six channel power amplifier. It
is designed to be used in all types of audio or audio/video systems.
Design and construction
The Reference 7250/7260 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 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 Reference 7250/7260 series II operates class A predriver and AB high current
MOSFET power output stages. It is capable of reproducing the most demanding audio
signals at rated power levels.
Features
Toroidal Transformers -
Discrete Circuitry -
Efficient, high current, shielded transformer.
More accurate and three dimensional reproduction of
source material.
Class A Predriver -
Improves low level detail for smoother, more musical
sound.
AB MOSFET Output Stage - For efficient linear power delivery and protection from
thermal overload
Gold Plated Connectors -
1% Metal Film Resistors -
High Current -
Improved 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.
Computer Grade Capacitors - Large capacity computer grade electrolytic capacitors for
extended low frequency control and improved dynamics.
Fused Outputs -
Provides protection from accidental shorting of amplifier
outputs.
Heavy Duty Binding Posts - Improved current carrying capacity and ease of use.
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P/N 13007 Rev.0004
Rear Panel View
1. AC fuse holder
4. Amplifier control muting input/output
2. AC Input receptacle
3. Speaker outputs
5. Level controls
6. Inputs
7. Speaker fuses
Rear panel description
1. AC fuse holder -
Holds the AC Line fuse. This fuse is a 15 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 6.
4. Amplifier control muting input/output -
To provide remote switching of mute on/off of the amplifier.
Explained further on pages (8 - 9).
5. Level controls -
6. Inputs -
For adjusting the input level of each channel into the amplifier.
There are five/six level controls on the back of the amplifier.
One level control for each channel.
For connecting signal patch cables (interconnects) from the
preamplifier to the amplifier to pass signal. Pages (5 - 6).
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P/N 13007 Rev.0004
7. Speaker Fuses - Protection against amplifier damage in the case of shorted speaker
wires. Replace fuse with same value 6 AMP SLOW BLOW only!
IMPORTANT!
Level controls
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
Example: When using 4 ohm and 8 ohm speakers together, the 4 ohm may sound louder
than the 8 ohm at a given volume level. The level controls on the amplifier are used to
match the speakers volume levels. Clockwise will increase the output. Counter
Clockwise will decrease the output.
Inputs
RCA type connectors accept line inputs from the preamplifier’s output connectors. There
are five/six input connectors, one for each channel, that may be used to connect the
amplifier to the preamplifier.
RCA cable connector
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P/N 13007 Rev.0004
Here is a typical preamplifier to amplifier setup:
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 positive (+) post should always be connected to the speakers (+)
jack. The negative (-) post should always be connected to the speakers (-) jack.
Spade connector Banana jack
Here is a typical amplifier output setup:
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P/N 13007 Rev.0004
System Installation
There will most likely be a number of cables involved in the installation of your home
entertainment system. Preplanning is essential in order to maximize system efficiency.
We recommend the following as a means of helping you reach that goal:
§
§
§
Make a diagram of your proposed system by laying out the relative location of each
component in the system. Then lay out the proposed cable runs between them.
Number each cable and record its length on the diagram for future reference.
Cable runs are critical in that they must be kept away from sources of power
radiation (amplifiers, power cords, heaters, etc...). For safety reasons, they
should also be kept out of traffic areas.
The process of optimizing the system will include the type of cable, the length of the
run, and the obstructions it must deal with along its run. Your dealer can advise you
on the products available and their relative merits. If building custom length audio
cables is not your strength, your dealer should be able to help you with that as well.
§
When possible, use a separate AC power line for the amplifier, one that is not
shared by any other household component. Important!
Tip: Take a piece of string (longer than the longest cable run) and mark it at each foot of length. Then do a
mock cable run using the string, dressing it neatly along the way. Count the divisions to the next full foot,
and add one foot to allow for some movement of the components. This will provide you with the ideal cable
length.
Making the connection
§
§
Before doing anything, insure that the power switch on the amplifier’s front panel is
in the ‘off’ position.
Again, it 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 house hold 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 plug it into the power
input receptacle in the rear panel. Do not connect it to the AC power source yet!
Connect the audio cables from your preamplifier’s output to the corresponding input
connector on the amplifier.
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P/N 13007 Rev.0004
§
Connect the wires from your speakers to the appropriate outputs on the amplifier. It
is absolutely essential that you observe correct polarity in these connections.
Example: If you connect your left front output of your preamplifier to channel 4 input on the amplifier,
remember to connect your left front speaker wires to channel 4's outputs. Always observe polarity when
connecting speakers, connect amplifiers (+) to the speakers (+) and amplifiers (-) to speakers (-).
§
§
Double check all connections.
Connect a playback unit (CD, VLD, Tuner, etc...) to the preamplifier. Turn the
volume on the preamplifier to minimum. Turn on the preamplifier, then the
amplifier (in that order). Set the source on the preamplifier to the playback unit
you’ve just connected. Turn the volume up slowly and listen for music from all
channels. If this is not the case, double check your installation.
§
Should you encounter any problems that cannot be traced to the source or the
material being played, consult the “TROUBLESHOOTING” section on page 10.
Note: When turning equipment ‘off’, the amplifier should always be turned off first, then
the preamplifier. When turning equipment ‘on’, the preamplifier should always be turned
on first, then the amplifier. Before turning anything on, insure the preamplifier is at a low
volume level.
Control muting
A control is provided on each Reference 7250/7260 series II 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 Reference
7250/7260 series II. If more than one amplifier is being controlled, the control signal can
be extended to include each successive unit by simply running a 1/8" MINI - JACK 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 E.
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P/N 13007 Rev.0004
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.
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
following table.
@ CTRL IN
Button position
Output status
@ CTRL OUT
Signal
Signal
No Signal
No Signal
OUT
IN
OUT
IN
Sound
Sound
Mute
Signal
Signal
No Signal
Signal
Sound
* 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.
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P/N 13007 Rev.0004
Troubleshooting
PROBLEM
POSSIBLE CAUSE
POSSIBLE SOLUTION
No sound
1. Reconnect power cord
2. Check AC switch or fuse
3. Check for shorts or
overloading
1. Power cord not plugged in
2. Power off at AC source
3. AC power inlet fuse blown or
faulty
4. Control switch in the wrong
position
(‘on’ LED not illuminated)
4. Place control switch in
proper position
No sound on some or all
selected channels (‘on’
LED illuminated
1. Speaker leads loose or faulty.
2. Line stage to amp cables loose 2. Tighten, repair or replace cable
or faulty.
1. Tighten, repair or replace cable
3. Source to line stage cables
loose or faulty.
3. Tighten, repair or replace cable
4. Line stage or source not
correctly selected.
4. Check all switch settings
5. Speaker fuse blown
6. Level controls adjusted
improperly
5. Check all speaker fuses
6. Re-adjust level controls
Sound lacks direction,
bass weak
1. Speakers connected out of
phase
1. Check connections making sure
that cables are connected (+)
to (+) and (-) to (-)
Loud hum or buzz on one 1. Poor ground connection in inter-
1. Check all connectors and repair
as necessary.
or more channels
connect cables.
Channel sounds distorted 1. Blown rail fuse
and low in output
1. Replace blown rail fuse inside
amplifier
** Note:If unit continues to blow power inlet fuses, DO NOT USE A HEAVIER
FUSE!!, have it serviced.
Care and cleaning
Under normal use, the amplifier will not require any special care. Over time you may
wish to clean the exterior of the unit by wiping it with a damp cloth to remove any dirt or
dust that accumulates on it. Do not let any liquid enter the amplifier through the vents in
the top cover. You may clean the connectors on the back panel with isopropyl alcohol
annually.
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P/N 13007 Rev.0004
Reference 7250/7260 series II SPECIFICATIONS
Power rating: 8 ohms
4 ohms
200 watts @ 1 kHz
375 watts @ 1 kHz
Frequency response
Input sensitivity
THD (S+N)
5 Hz - 45 kHz
1.4 Volts
0.09 % @ 1 kHz
Input impedance
Damping factor
Current (peak to peak)
Slew rate
33.2 k ohms
450
75 Amps
14 V / usec
Dynamic headroom
S/N (A-weighted)
Voltage gain
1.2 dB
95 dB
28
Line voltage
120/220/240 VAC switchable
17"(w) X 19.25"(d) X 7.25"(h)
70 lb
Dimensions (O.A.)
Weight
Power consumption
1830 watts max
17.5 Amps max current draw
130 watts @ no input
Replacement fuses
Line -15 Amp/250 Volt Slow Blow
Rails - 6 Amp/250 Volt Slow Blow
Speaker - 6 Amp/250 Volt Slow Blow
In-rush - 2 Amp/250 Volt Slow Blow
Control - .5 Amp/250 Volt Fast Blow
Page 11
P/N 13007 Rev.0004
Limited Warranty
B&K Components Ltd., referred to herein as B&K, warrants your B&K equipment against all defects in
material and workmanship for a period of five years from the date of purchase. This warranty applies only
to the original purchaser and only to equipment in normal residential use and service. Defective equipment
must be returned to B&K, prepaid, accompanied by sufficient payment to cover the cost of return shipping
and handling, and will be repaired or replaced at the discretion of B&K whose decision as to the method of
reparation will be final.
This warranty shall not apply to any equipment which is found to have been improperly installed, incorrectly
fused, misused, abused, or subjected to harmful elements, used in any way not in accordance with
instructions supplied with the unit, or to have been modified, repaired or altered in any way without the
expressed, written consent of B&K. This warranty does not apply to the cabinet, the remote controller, or
appearance items such as the faceplate, control buttons, or display lenses, nor does it cover any expenses
incurred in shipping the unit to and from the manufacturer’s service depot.
No warranty, implied or otherwise created by State law shall extend beyond the terms of this warranty and
B&K shall not be liable for any incidental or consequential damage arising out of a defect in material or
workmanship of the unit during the terms of this warranty or thereafter. Some States do not allow the
exclusion or limitation of incidental or consequential damages and the foregoing exclusions may not apply to
you.
This warranty gives you specific legal rights. Your may also have other rights which vary from State to
State.
No agent, representative, dealer or employee of B&K has the authority to increase or alter the obligations or
terms of this warranty.
B&K Components Ltd.
RETURNING EQUIPMENT
No equipment may be returned to B&K Components Ltd. Without a RETURN AUTHORIZATION. Should
you find it necessary to return equipment to B&K, for any reason, a RETURN AUTHORIZATION (RA)
number must be issued by B&K in respect of the equipment being returned. You may request an RA
number by calling B&K at the numbers below. We ask that you provide the following information at that
time.
1.Your name, address, and phone number.
2.The model and serial number of the equipment being returned.
3.A description of the problem being experienced.
Your call will be referred to a Technical Service Representative who will work with you to resolve the
problem. If it is determined that the unit must be returned for repair, an RA number will be issued.
B&K Components Ltd. 2100 Old Union Road, Buffalo New York 14227
1-800-543-5252 or 1-716-656-0023
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P/N 13007 Rev.0004
B&K Components, Ltd 2100 Old Union Road Buffalo, New York 14227
P/N 13007 Rev.0004
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