Devices, Inc.
TA250/TA450
DUAL CHANNEL AMPLIFIERS
INSTALLATION AND
OPERATION MANUAL
Copyright 1995 by SMART Devices, Inc.
5945 Peachtree Corners East
Norcross, GA 30071-1337
1-800-45-SMART
or
770-449-6698
Table of Contents
Circuit Description -- 3
Construction -- 3
Installation -- 3
Power Connections -- 3
Thermal Protection -- 3
Fan Assist Cooling -- 4
Controls/Connections -- 4
BRIDGED MONO OPERA TION -- 5
SPECIFICA TIONS: -- 5
Copyright 1995 by SMART Devices Inc.
5945 Peachtree Corners East
Norcross, GA 30071-1337
SMART products are designed to deliver unsurpassed quality in workmanship and performance. The following information gives detailed instructions on the installation and operation of the SMART TATA250/450
amplifier. We strongly encourage new owners of the TATA250/450 to thoroughly read this entire manual
before placing their new SMART product into service. This will ensure that the TATA250/450 will be operated properly to give the superior performance that it was designed to deliver.
For service or installation assistance, please call our
Technical Support Department between the hours of
8 a.m-5 p.m. E.S.T., Mon.-Fri.
1-800-45-SMART
LIMITED WARRANTY: SMART products and accessories are warranted against malfunction or failure due to defects in
workmanship or materials for a period of one year from the date of shipment. If a problem occurs during the warranty period, the unit will be repaired, or replaced at our option, without charge for materials or labor. If air freight is requested by the
dealer, the difference between air and surface charges will be billed to the dealer. This limited warranty does not cover
products that have been abused, altered, modified, or operated in other than specified conditions. Prior factory approval is
required on all returns. Returned equipment or defective parts must be shipped freight prepaid to us by the dealer or customer.
Our limited warranty does not cover damages resulting from accident, misuse or abuse, lack of responsible care, or failures not attributable to manufacturing defects, except as provided herein. SMART Devices, Inc. makes no warranties, express or implied, including warranties of merchantability or fitness for a particular purpose.
RETURN POLICY: Factory authorization MUST be obtained before returning any product. A 15% restocking charge will be
issued on unused equipment (in original box) that is returned for credit. Credit is issued to the dealers account. The credit
may be used against future purchases and no cash transactions are offered. All returns must be shipped freight prepaid by
the dealer. Equipment returned without a factory RA (Return Authorization) will be refused.
Installation and Service ManualInstallation and Service Manual
Installation and Service Manual
Installation and Service ManualInstallation and Service Manual
TA250/450 Power AmplifierTA250/450 Power Amplifier
TA250/450 Power Amplifier
TA250/450 Power AmplifierTA250/450 Power Amplifier
Circuit Description
To assure absolute long term reliability, the output section of each channel incorporates multiple Motorola
Power Transistors, which provide 3 times the amplifiers rated power in watts of dissipation per channel. The
output stage is arranged in a full complimentary format
for class AB/2 operation.
The bias current is evenly distributed among all output
devices. Bias thermal compensation is accomplished
by a thermally bipolar semiconductor junction to the
heat producing output device. Triple diffused high
power driver transistors are employed along with high
speed, high voltage silicon annular devices for the
predriver and inverter stages. Utilization of these components provides the required separation of Ft break
points for absolute stability. Full complimentary drive
and loading is employed throughout. Only 20 dB of
negative feedback is used to reduce forward transfer
distortion to minimum levels. V1 type energy limiters
are incorporated for short circuit protection of the amplifier. Due to the unusually large safe operating area
of the output stage, the limiters do not activate until
driving a forty-five degree reactive load under 2 ohms at
full power.
Construction
The amplifiers are designed on an all modular concept
permitting rigorous preassembly module testing and
maximum service accessibility. Each functional module is fully tested before final assembly. Although components of the highest quality are used throughout,
each amplifier is burned in, prior to shipment, at the
worst case operating point to eliminate any possibility
of component malfunction. All chassis components are
precision machined from high quality aluminum and
sheet steel stock. The entire package concept is directed
toward maximum efficiency of space and structure, accounting for the unit’s compact size and light weight.
Installation
All SMART amplifiers are designed for mounting in a
standard 19 inch equipment rack, or one of the many
rack type portable cases available on the market. The
amplifiers require 3-1/2 inches of vertical panel space,
with 13-1/2 inches required behind the panel. Total
depth, Including handles, is 14-3/4 inches, Front panels are machined from solid aluminum stock with a
black textured finish and sturdy rack mount handles.
Placement of the amplifier is not critical for normal operating conditions, provided that sufficient air flow is
allowed to reach the heat sink array. If the unit is. to be
placed on a shelf, or a similar unenclosed area, allow
four inches clearance behind the heat sink to permit
vertical air flow through the array, For installation in a
cabinet, allow an additional two inches above and one
inch below the amplifier to permit air to be drawn
around the back of the unit. If the amplifier is to be
mounted in an equipment rack or cabinet with other
heat producing equipment, ensure environmental operating temperatures do not exceed 55C (131F). Should
overheating occur because of inadequate ventilation,
thermal protection circuitry will automatically protect
the amplifier. When a safe operating temperature is restored, the amplifier will resume normal operation.
Because the amplifiers are capable of delivering high
power from a relatively small physical package, considerable heat can build up in cabinets containing several
instruments. A good rule of thumb to adopt is; “Provide forced air cooling in any enclosure containing four
or more instruments.”
Power Connections
SMART power amplifiers are specified for operation
from 120-240 Volt, 50-60 Hz mains supply.
Equipment for domestic (USA) consumption includes a
captive cord with a three pin polarized plug. DO NOT
REMOVE THE CENTER GROUNDING PIN! In new
installations and portable sound systems, or any situation in which the mains power is suspect, it is wise to
confirm appropriate voltage and line polarity BEFORE
connecting the instrument to power sources.
Thermal Protection
Certain conditions of operation (restricted airflow cooling, sustained high power operation into low impedance loads) can result in an increase in output device
case temperature sufficient to affect any amplifiers performance.
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Should the heat sink reach 95C, thermal protection circuitry will automatically disconnect the amplifier’s output stage from the load (loudspeaker) until the temperature decreases sufficiently. The action of removing the
load eliminates output current, resulting in an immediate temperature drop. The thermal protection circuit
will automatically reconnect the load when the temperature drops below 95C.
Fan Assist Cooling
To provide continuous operation under adverse operating conditions, a Dual Fan Forced Air Cooling System
has been added for extra protection.
INSTALLATION & OPERA-
GROUND/LIFT SWITCH
To eliminate ground loops between this amplifier and a
preamplifier in certain installations, a GROUND/LIFT
SWITCH is provided.
INPUT SIGNAL SELECTOR SWITCH
This switch is used to select one of three input configurations.
1) PARALLEL: The input signal is applied to Channel
One only. Channel One and Two inputs are connected
in parallel and the same signal at both Channel One
and Channel Two outputs.
Temperature is controlled automatically by a thermal
switch which turns on the Cooling System when required.
Controls/Connections
POWER SWITCH
To turn the amplifier ON or OFF, press the upper or
lower portion of this rocker switch.
POWER INDICATING LED
This LED indicates power is turned ON.
LEVEL CONTROLS
Each channel has a separate low noise 41 click detent
rotary level control. Rotate controls clockwise to increase level.
SIGNAL STATUS INDICATORS
Two green LED indicators are normally off with no signal present and illuminate when signal is present.
CLIP INDICATORS
Two red LED indicators illuminate when the amplifier
has reached full power, If the amplifier is driven into a
clip condition, a Softclip circuit is activated attenuating
the input signal and preventing a Hard Clip condition
where the amplifier’s output saturates to a DC level.
NOTE: Channel Two’s input becomes a signal output
for use in Daisy Chaining additional amplifiers.
2) STEREO: This is the amplifiers standard mode of operation where channel inputs and outputs corresponds
(Chan. 1 in = Chan. 1 out and Chan. 2 in = Chan. 2 out.)
3) BRIDGED: This mode is used to obtain the highest
power output levels possible from the amplifier. Both
Channels combine to form a single high power mono
output. See Bridged Mono Operation Pg. 9.
OUTPUT CONNECTIONS
Output connections are made via five-way binding
posts. Polarity is indicated by red and black terminals.
We suggest the use of dual banana plugs for convenient
and reliable hook-up. They also allow quick connection changes, when reversing polarity, as required during test and calibration of multilevel biamplified and
triamplified systems. Heavy Class 11 wire may be used
by unscrewing the large plastic portion of the output
terminal and inserting the wire into the hole provided.
EXTREMELY IMPORTANT:
When making wire connections, Double Check that NO
wire strands or ends touch an adjacent terminal, shorting the output.
1/4” JACK INPUT CONNECTIONS
Balanced and Unbalanced inputs can be accepted via
the 1/4” Jack. Balanced inputs: Tip = High, Ring =
low, Sleeve = Ground.. Unbalanced inputs: Tip = High,
Sleeve = Ground.
Note: The Unbalanced 1/4” Jack parallels the XLR
connector for easy daisy chaining of amplifier inputs.
XLR INPUT CONNECTIONS
XLR input connectors are provided for balanced input
signals. Please note; Pin 1: Ground, Pin 2; High, Pin 3:
Low
CAUTIONS:
Never strap the two red output terminals together (in
parallel).
Never connect either red output terminal to chassis
ground.
FUSE HOLDER
The Fuse Holder contains the Primary AC Fuse. The
fuse should only be replaced with one of the same type.
If the fuse continues to blow out, stop replacing the fuse
and refer servicing to qualified personnel.
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TA250/450 Power Amplifier
AC POWER CORD
Plug the Power Cord into an AC outlet that delivers the
proper voltage and current for amplifier operation.
CAUTION:
The TA250 and TA450 amplifiers are a product of the
most advanced technology and manufacturing techniques. The amplifiers are fully protected against overheating, input overload and shorted or mismatched
loads. As is the case with any precision instrument,
some care should be taken in the unit’s operation. The
following precautions should be noted and adhered to.
Damage resulting from their omission is not covered
under the terms of the warranty.
1) DO NOT PARALLEL THE TWO OUTPUTS OF
EACH CHANNEL BY CONNECTING THEM TOGETHER OR PARALLEL THEM WITH ANY OTHER
AMPLIFIER OUTPUT.
2) NEVER CHANGE A FUSE WITH AC POWER CONNECTED.
3) UNDER NO CIRCUMSTANCES SHOULD THE AMPLIFIER BE OPERATED WITH THE COVER REMOVED. THERE ARE NO USER SERVICEABLE COMPONENTS INSIDE THE AMPLIFIER. AVOID POTENTIALLY DANGEROUS SHOCK HAZARDS. REMEMBER TO KEEP THE COVER CLOSED AT ALL TIMES.
BRIDGED MONO OPERA TION
1. Set the INPUT SELECTOR SWITCH to BRIDGE.
2. Connect the input signal to Channel One’s input
jack.
3. Connect the speaker load to the two red terminals of
each channel. Confirm the (+) terminal of the speaker to
channel one and the (-) terminal to channel two.
SPECIFICATIONS:
Gain:
26 dB (per Channel) TA250
28 dB (per Channel) TA450
Continuous Power:
145 watts per Ch. @ 8 ohms TA250
240 watts per Ch. @ 4 ohms TA250
200 watts per Ch. @ 2 ohms TA250
400 watts bridged mono @ 8 ohms TA250
300 watts bridged mono @ 4 ohms TA250
270 watts per Ch. @ 8 ohms TA450
425 watts per Ch. @ 4 ohms TA450
290 watts per Ch. @ 2 ohms TA450
765 watts bridged mono @ 8 ohms TA450
600 watts bridged mono @ 4 ohms TA450
Frequency Response:
Plus/Minus 0.5 dB, 20 Hz to 20 KHz
Distortion:
< 0.25% THD or IM, .01W to rated power, 20 Hz to 20
KHz (0.01% typical)
Input Sensitivity:
1.0 Vrms standard with 0.775 Vrms and 1.5 Vrms internally selectable.
Hum and Noise:
104 dB below rated output (unweighed 20 KHz bandwidth)
Input Impedance:
15K ohms, nominal
Transient Inter Modulation Distortion:
< 0.02%
4. DO NOT use the black terminals of either channel.
5. Assure the speaker impedance is 4 ohms or above.
6. Adjust output using Channel One control and Set
Channel Two level to “0”
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