Altec Lansing 4200A, 6125A User Manual

Page 1
6125A
4200A
Multi-channel power amplifiers
Altec Lansing PrAltec Lansing Pr
Altec Lansing Pr
Altec Lansing PrAltec Lansing Pr
1000 W. Wilshire Blvd. Suite 362
A division of Altec Lansing Technologies Inc, Milford PA 18337-0277 Made In USA
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
Table Of Contents
1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 UNPACKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 AC POWER REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1 Voltage Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2 Current Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.3 AC Grounding & Earth Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 CABLE REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1 Input Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.2 Output Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5 RACK-MOUNTING REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1 Mechanical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.2 Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.3 Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6 FRONT PANEL FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7 REAR PANEL FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1 Input Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.2 Input Ground Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.3 Multi-Channel Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.4 50Hz Low Cut Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.5 Input Level Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.6 Stereo/Mono Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.7 Dual Channel Mode/Bridge Mode Switches . . . . . . . . . . . . . . . . . . . . . . 8
7.8 Loudspeaker Output Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.9 AC Inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8 SELF-PROTECTION FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1 Power Supply Undervoltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.2 Power Supply Overvoltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.3 Output Overcurrent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.4 Heat Sink Overtemperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.5 Unacceptable DC or High Frequency Output Content . . . . . . . . . . . . 10
8.6 AC Power Interruption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9 TYPICAL APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1 Six Channel Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.2 Dual Mono Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.3 Bridged Mono Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.4 Typical PA Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
10 DESIGN THEORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
11 TROUBLESHOOTING TIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
11.1 No Audio Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
11.2 Distorted Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
11.3 Hum or Buzz Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
12 DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
13 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
14 WARRANTY INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Caution: Caution:
Caution:
Caution: Caution:
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CAUTION
RISK O F ELECTR I C SH OCK
DO NOT OPEN
The lightning flash with arrowhead symbol, within an equalateral triangle, is intended to alert the user to the presence of uninsulated "danger­ous voltage" within the product's enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons.
TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER. NO USER SER-TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER. NO USER SER-
TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER. NO USER SER-
TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER. NO USER SER-TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER. NO USER SER-
VICEABLE PVICEABLE P
VICEABLE P
VICEABLE PVICEABLE P
TO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE THISTO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE THIS
TO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE THIS
TO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE THISTO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE THIS
ARAR
TS INSIDE. REFER SERTS INSIDE. REFER SER
AR
TS INSIDE. REFER SER
ARAR
TS INSIDE. REFER SERTS INSIDE. REFER SER
APPLIANCE TO RAIN OR MOISTURE.APPLIANCE TO RAIN OR MOISTURE.
APPLIANCE TO RAIN OR MOISTURE.
APPLIANCE TO RAIN OR MOISTURE.APPLIANCE TO RAIN OR MOISTURE.
VICING TO QUALIFIED SERVICING TO QUALIFIED SER
VICING TO QUALIFIED SER
VICING TO QUALIFIED SERVICING TO QUALIFIED SER
equalateral triangle is intended to alert the user to the presence of important operating and main­tenance instructions in the literature accompany-
ing the device.
The exclamation point within an
VICE PERSONNEL.VICE PERSONNEL.
VICE PERSONNEL.
VICE PERSONNEL.VICE PERSONNEL.
ss
s
ss
TO REDUCE THE RISK OF FIRE, REPLACE ONLTO REDUCE THE RISK OF FIRE, REPLACE ONL
TO REDUCE THE RISK OF FIRE, REPLACE ONL
TO REDUCE THE RISK OF FIRE, REPLACE ONLTO REDUCE THE RISK OF FIRE, REPLACE ONL
REFER REPLACEMENT TO QUALIFIED SERREFER REPLACEMENT TO QUALIFIED SER
REFER REPLACEMENT TO QUALIFIED SER
REFER REPLACEMENT TO QUALIFIED SERREFER REPLACEMENT TO QUALIFIED SER
WW
ARNING: THIS APPARNING: THIS APP
W
ARNING: THIS APP
WW
ARNING: THIS APPARNING: THIS APP
ARAARA
TUS MUST BE EARTUS MUST BE EAR
ARA
TUS MUST BE EAR
ARAARA
TUS MUST BE EARTUS MUST BE EAR
POWER LINE CORDPOWER LINE CORD
POWER LINE CORD
POWER LINE CORDPOWER LINE CORD
Y WITH SAME TYPE FUSE.Y WITH SAME TYPE FUSE.
Y WITH SAME TYPE FUSE.
Y WITH SAME TYPE FUSE.Y WITH SAME TYPE FUSE.
VICE PERSONNEL.VICE PERSONNEL.
VICE PERSONNEL.
VICE PERSONNEL.VICE PERSONNEL.
THED THROUGH THE SUPPLIEDTHED THROUGH THE SUPPLIED
THED THROUGH THE SUPPLIED
THED THROUGH THE SUPPLIEDTHED THROUGH THE SUPPLIED
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
1. INTRODUCTION
The 6125A and 4200A power amplifiers combine
the efficiency of a MOSFET high-speed switching output stage with the sophistication of modern microprocessor and DSP technology to produce a multi-channel amplifier with unprecedented versatility and power in a single 3RU pac k­age.
Although similar to other amplifiers with class D
output stages, the 6125A and 4200A amplifiers employ internal microprocessor and DSP algorithms to optimize output switching characteristics and eliminate the usual harshness associated with high-frequency audio in stan­dard class D amplifiers. This optimization results in a spread-spectrum switched output that varies with input amplitude and frequency , and minimizes radiated emissions by eliminating the single-frequency high-energy radiated interference normally associated with switching outputs. The use of a simple linear power supply removes another potential source of radio-frequency interference, an im­portant consideration as racks become more and more heavily populated with digital signal processing equipment. A small switching supply using flyback topology provides an efficient power source for logic, protection, pre-ampli­fier and indicator circuits.
To assure reliable operation, the usual protection
from excessive high-frequency, DC offset, and thermal overload is supplemented by power supply undervoltage, power supply overvoltage, and output overcurrent detec­tion, all monitored and controlled by the latest in minia­turized microprocessor technology.
In sum, 6125A and 4200A amplifiers combine the
best of the new digital technologies with the best of the traditional analog technologies to provide a product that will supply clean sound at full output from every channel while generating minimal heat, thus increasing the reli­ability of every other piece of equipment in a rack as well as preserving its own.
2. UNPACKING
As a part of our system of quality control, every
Altec Lansing product is carefully inspected before leav­ing the factory to ensure flawless appearance. After un­packing, please inspect for any physical damage. Save the shipping carton and all packing materials, as they were carefully designed to reduce to minimum the possibility of transportation damage should the unit again require packing and shipping. In the event that damage has oc­curred, immediately notify your dealer so that a written claim to cover the damages can be initiated.
The right to any claim against a public carrier can be forfeited if the carrier is not notified promptly and if the shipping carton and packing materials are not avail­able for inspection by the carrier. Save all packing mate­rials until the claim has been settled.
3. AC POWER REQUIREMENTS
3.1 Voltage Requirements
The 6125A and 4200A amplifiers can be operated from nominal 120VAC or 240VAC, 50/60Hz mains. This is user-configurable by changing the insert in the AC Inlet (See section 7.9). The power connector on the amplifier accepts a standard IEC-320 receptacle.
For nominal 120VAC operation, the power cord should be three-conductor, rated for at least 13A (16AWG). The line fuse should be type MDA, 12A.
For nominal 240VAC operation, the power cord should be three-conductor, rated for at least 10A (18AWG). The line fuse should be type MDA, 10A.
3.2 Current Requirements
1.) Idle (no audio):
6125A 4200A
120V: 0.81A 120V: 0.9A 240V: 0.42A 240V: 0.5A
2.) With typical audio inputs:
8 loads on all channels
120V: 4A 120V: 4.6A 240V: 2A 240V: 2.3A
4 loads on all channels
120V: 6.5A 120V: 7.0A 240V: 3.3A 240V: 3.5A
6125A and 4200A amplifiers consume less than 12 amps when all channels operate at 1/8 power into rated (4 ohm) loads. This condition satisfies the UL, CSA and building electrical code requirements for a piece of audio equipment not to consume more than 80% of the current available when plugged into a grounded 15 amp outlet and operated at 1/8 of maximum power.
3.3 AC Grounding and Earth Grounding
T o reduce the risk of g round loop hum, all system ground references should originate at the same point in your A C po wer distribution. Do not remo ve the amplifier’s ground pin, as it creates a potential shock hazard.
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
4. CABLE REQUIREMENTS
4.1 Input Cables
Be sure to use shielded cable whether balanced or unbalanced. Shielding which is properly grounded will protect the signal from outside electrical interference such as RF, fluorescent lighting, and computer/display emis­sions. As a general rule, unbalanced or single-ended (tip­sleeve) lines of less than 10 feet are satisfactory, but greater distances or noisy field environments require a balanced signal. Avoid running input lines in close proximity or parallel to long speaker lines, AC power cables, or power transformers, as this may generate hum or oscillation.
4.2 Output Cables
These amplifiers are capable of delivering high levels of output current, therefore the wire gauge used for speaker cables is particularly important. Inadequate wire gauge can add significant resistance to the speaker’s own impedance, especially over long distances, reducing the power which is actually delivered to the speaker. It could also result in a decreased damping factor and possible fire hazard. Since power at the speaker load is of primary con­cern in system design, we have included a table to best determine appropriate wire gauge for your application. The following table lists the resistance per 100 feet of com­mon copper wire gauges, and also gives the percentage of the speaker load power which would be lost in an arbitrary 100 ft run of different gauges of 2-conductor copper speaker wire.
5. RACK-MOUNTING REQUIREMENTS
5.1 Mechanical
The 6125A and 4200A amplifiers are designed to fit in standard 19-inch equipment racks. The front panel rack-mount ears are sufficiently strong for most applica­tions, however if you desire further integrity for mobile racks, we recommend using the four additional holes in the back of the chassis for supplemental rear-mounting (see dimensional drawing for details).
5.2 Cooling
Be certain that both the front and back of the rack have unhindered access to free air flow. Fan direction is from front to back. It is not necessary to leave empty space above or below.
5.3 Grounding
In some installations where the sound system is sensitive to RF noise or system-induced oscillation, it may be necessary to ground the amplifier’s chassis to the rack enclosure. This is accomplished using star type lockwashers on the four rack mounting screws. These star washers will penetrate through the amplifier’s paint to ad­equately ground the chassis to the rack.
Wire Gauge Ω/100ft 8Ω load 4 load
#8 .0605 0.8% 1.5% #10 .1018 1.3% 2.5% #12 .1619 2.0% 4.0% #14 .2575 3.2% 6.4% #16 .4094 5.1% 10.2% #18 .6510 8.1% 16.3%
Table 4.1: Wire gauge resistance/power loss
This table expresses the power loss as a percent- age of the load’s po wer rather than the total amplifier out­put power in order to accurately determine power loss at other cable lengths. For example, if you plan to deliver 150 watts to an 8 load through 50 ft of 14 ga. cable, the power loss in the cable would be half that of a 100 ft run of #14 wire as shown in the table, or 1.6% of 150W, which is an insignificant 2.4 watts. However, if you were to run 200 ft of 18 ga. cable to a 4Ω load, the loss would be twice that of the 100 ft run shown in the table, or 32.6% of 250W, which is 81.5 watts lost as heat. Always be sure to use adequate gauge speaker wire.
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
6. FRONT PANEL FEATURES
6.1 Power Switch
When the unit is switched on there is a five sec-
ond delay, during which time the PROTECT circuit will activate, disconnecting the speakers from the amplifier output. When turning off the amplif ier, the load is remo ved instantly, and the protect LED will briefly turn on as the power supply discharges.
6.2 Signal Indicator
The signal present LEDs illuminate at an input
level of about 13mVrms (-35.5dBu).
6.3 Clip Indicator
The clipping LEDs illuminate at an input level of
about 870mVrms (+1.0dBu), with all channels driven by 1KHz into 8. This indicates that the signal processing circuitry has determined output levels to be approaching the available po wer supply rails and has be gun to “soften” signal peaks. Actual onset of “hard” clipping depends on audio program and total load impedance and does not oc­cur until the signal processing circuitry can no longer com­pensate, which means that signal integrity can be maintained even if the clipping indicators illuminate for short periods of time.
6.4 Thermal Status Indicator
The thermal LEDs illuminate when the tempera-
ture of any one of the heat sink extrusions reaches 85 to 90°C. Both channels of the affected amplifier module will shut off until the measured temperature drops below about 70°C. The amplifier should be able to maintain proper
operation at an ambient room temperature of 50°C (122°F) or less with typical audio program and all channels driven into 4Ω.
6.5 Protect Indicator
The protect LEDs illuminate when the fault moni­toring microprocessor has determined that one of the fol­lowing conditions exists:
- Power supply undervoltage
- Power supply overvoltage
- Output overcurrent
- Heat sink overtemperature
- Unacceptable DC output content
- Unacceptable high frequency output content
- AC power interruption
Because the signal processing module used in the 6125A and 4200A amplifiers processes two channels si­multaneously, a fault in one channel will result in a pro­tect condition for both channels processed by the same module, ex. channels 1-2, 3-4, and 5-6 (6125A only). Thus there will never be a case where only one of the amplifier channels is shown in protect mode. When a pair of protect LED's are illuminated, internal relays have removed the channel pair's speaker loads from the amplifier output and connected the speakers to ground. If the fault is isolated to one module (channel pair), the other channels will re­main unaffected.
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
* Model 6125A shown - Model 4200A only has channels 1-4.
7. REAR PANEL FEATURES
7.1 Input Connectors
The 6125A and 4200A inputs use balanced two piece "Euroblock" style connectors. It is recommended that balanced input connections be used whenever possible to take full advantage of the amplifier's common mode rejection properties, and to reduce ground-loop problems. If a hum problem persists even though balanced inputs are used, try connecting a balanced signal to the Euroblock input with the input cable's shield lifted at the amplifier end of the cable (ie. no ground connection), but connected to ground at the signal source. This eliminates potential ground currents through the input cable yet preserves the benefits of shielding. If connecting an unbalanced signal to the Euroblock input, connect the signal wire to (+) and the cable shield to both (-) and ground.
G
-
+
Euroblock
Connector
System
G
-
+
7.2 Input Ground Switch
This switch separates the input signal ground from the chassis ground on all inputs. Ground connections from an incoming signal float from the chassis ground when the switch is out. Unless there ar e special circumstances which
require the input signal ground and chassis ground to be disconnected, it is best to leave this switch in.
7.3 Multi-Channel Operation
The 6125A is essentially three stereo amplifiers in one chassis, for a total of up to six separate channels. The 4200A is essentially two stereo amplifiers in one chas­sis, for a total of up to four separate channels. Thus, the following references to Stereo, Mono, or Bridged opera­tion is with regard to each of three or two pairs of chan­nels in the amplifier . For e xample, Channel 1 and Channel 2 together can provide stereo, mono, or bridged operation, completely independent of Channels 3-4 or Channels 5-6 settings.
7.4 50Hz Low Cut Switch
Each pair of channels has a 50Hz second order (12 dB per octave) low-cut filter option which is applied to both channels within the pair. When the switch is pressed, the audio signal is -3dB at 50Hz, -15dB at 25 Hz,
-27dB at 12.5Hz, etc.
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
Model 6125A shown.
Model 4200A has only four channels.
7.5 Input Level Controls
Input Level Controls attenuate input signal from
0dB down to -. For best performance, Altec recommends that the level controls be operated at full level (0 dB at­tenuation).
In STEREO mode, each level control corresponds
directly to the input signal on its respective channel.
In MONO Mode, the input signal connected to channels 1, 3, or 5 are used to drive channels 2, 4, or 6 respectively, and the level controls for channels 1, 3, and 5 likewise control channels 2, 4, and 6. When switched to
Mono mode, channels 2, 4, or 6 level controls become in­active.
In BRIDGED mode, the level controls function the same as in mono mode.
7.6 Stereo/Mono Switch
The 6125A is comprised of three stereo amplifi­ers (two on the 4200A), each operating independently of the others, with Stereo/Mono switching available for each channel pair. If this switch is set to Stereo mode, the chan­nel pair operates as two discrete amplifiers, each with its own input connection and level control.
Switching to Mono mode allows one input (chan­nel 1, 3, or 5) to drive both channels of a stereo channel pair. Pressing the Mono switch disables the channel pair's
other input connection, as well as its level control. The first channel's input and level control now determines the signal to both channels.
7.7 Dual Channel/Bridge Mode Switch
Bridging a power amplifier is the process wher eby two channels are supplied the same signal, with the sec­ond channel's phase inverted 180°. The speaker is then connected across the (+) output connections of each chan­nel, resulting in twice the power to the speaker that either channel could deliver by itself. Since in Bridge Mode both
connections have voltage present, never connect or touch either speaker wire to ground.
The 6125A is capable of three channels of bridged output (two channels on the 4200A). T o use bridged mode , first press MONO from the Stereo/Mono switch on the channel pair to be bridged. This sends the same audio signal to both channels. Then press BRIDGE from the Dual/Bridge switch on the channel pair to be bridged. This inverts the phase of the input signal to the second channel. These two channels are now operating together in Bridged Mono mode, and the output must be taken from the two (+) terminals of the corresponding bridged channel pair
7.8 Loudspeaker Output Connectors
Three terminal blocks (two on the 4200A) pro­vide connections for the speaker outputs. In BRIDGE mode, the channel 1, 3, or 5 (+) connection is the Bridged (+) speaker output terminal, and the channel 2, 4, or 6 (+) connection is the Bridged (-) speaker output.
CAUTION! NEVER CONNECT THE TWO BRIDGED OUTPUTS TOGETHER OR CONNECT EITHER BRIDGED OUTPUT TO GROUND.
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Model 6125A shown.
Model 4200A has only four channels.
Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
Outputs
7.9 AC Inlet
The 6125A and 4200A amplifiers can be config­ured by the customer for operation at either 115VAC or 230VAC mains. Switching from one to the other simply requires the following steps:
1.) Unplug the amplifier from the wall and re-
move the power cord from the rear of the amplifier.
2.) Using a small screwdriver as a lever, unlatch
the fuse holder in the AC inlet and remove it.
3.) Remove the voltage selection insert and ro­tate until the new nominal mains voltage level indication (115 or 230) is on top and properly oriented for reading.
4.) Replace the voltage selection insert in the AC inlet, making sure that it is plugged in all the way.
5.) Replace the fuse with the appropriate size (see #6 below), and press the fuseholder back into the AC inlet until it latches.
6.) Using a power cord of the appropriate size and with the appropriate terminations, plug the cord into the rear of the amplifier and then into the wall. The ampli­fier is now ready for use at the new mains voltage.
If the mains voltage is 110-125VAC, the required fuse is MDA 12, 250V, and the required power cord is 3­wire grounded, 13 Amp (16AWG) minimum.
If the mains voltage is 220-250VAC, the required fuse is MDA 10, 250V, and the required power cord is 3­wire grounded, 10 Amp (18AWG) minimum.
8. SELF-PROTECTION FEATURES
The 6125A and 4200A amplifiers contain circuitry to self-protect during extreme fault conditions. These fault conditions are:
1.) Power supply undervoltage
2.) Power supply overvoltage
3.) Output overcurrent
4.) Heat sink overtemperature
5.) Unacceptable DC or high frequency output content
6.) AC power interruption
Except for AC power interruption, the detection of any fault will result in the activation of protection cir­cuitry on a particular module, which consists of two chan­nels. That is, a short circuit on the output of channel 1 will result in both channel 1 and channel 2 entering pro­tect mode. This is because the signal processing module, which processes both channels simultaneously, does not distinguish between the two channels within a channel pair when processing a fault.
An AC power interruption will result in all chan­nels entering protect mode simultaneously, just as if the amplifier is being turned off.
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
In all cases, the amplifier will restart the signal processing module after a short delay and will reconnect the speakers after several seconds if no further fault con­ditions exist. This allows the servo circuitry to bring any residual DC offsets to zero before speakers are connected.
Specific conditions resulting in a fault are as f ollows:
8.1 Power supply undervoltage - less than about
55 volts on the either supply rail. Possible causes would be total load on the outputs exceeding recommendations (remove some speakers - 4 load min, 8 min bridged), low AC mains voltage (reduce extension cord length or increase wire size, or switch to an AC mains circuit more capable of supporting the amplifier's power requirements), or improper AC inlet mains voltage setting (make sure nominal A C mains voltage matches the number in the vie w­ing window on the AC inlet).
8.2 Power supply overvoltage - more than about
92 volts on either supply rail. Possible causes would be high A C mains v oltage (change to an A C mains circuit with voltage within the amplifier's stated requirements) or im­proper AC inlet mains voltage setting (make sure nominal AC mains voltage matches the number in the vie wing win­dow on the AC inlet).
8.3 Output overcurrent - more than 15 to 20 amps
being drawn from any output. Possible causes would be total load on the affected output exceeding recommenda­tions (disconnect some speakers), or a short circuit on one of the outputs driven by the affected module (inspect speaker wiring for proper connection).
The above conditions are checked by the signal processing module on a switching cycle by switching c ycle basis and are therefore monitored as often as a million or more times a second, allowing protection well before de­structive conditions have time to cause part failure.
8.4 Heat sink overtemperature - a measured heat
sink extrusion temperature of more than 85 to 90 degrees C. The three-speed fan will switch to medium speed at an extrusion temperature of 45 to 50 degrees C, and to high speed at a temperature of 70 to 75 degrees C. The overtemperature fault will clear itself when the measured temperature is below about 70 degrees C. The fan will operate at low speed below about 50 degrees C.
8.5 Unacceptable DC or high frequency output
content - a DC offset in the output signal of more than a
few hundred millivolts indicates module failure, and will trigger a DC protect fault. High frequency (20kHz to 100kHz) in the output at high amplitudes can cause speaker damage and causes a fault condition more or less rapidly as frequency and amplitude vary.
These two conditions (DC and HF) are tested by the same circuit so the exact cause cannot be isolated. If the fault condition persists after disconnecting all inputs and outputs from the amplifier, there is proba bly a module failure requiring service. Note: the self-testing circuit may
take as long as 30 seconds to recover from this fault, so be sure to give the amplifier enough time to reset itself. If
after 30 seconds the module has recovered, begin plug­ging in one input and output at a time in an effort to iso­late a system high-frequency or oscillation problem.
8.6 A C po wer interruption - a dropout (or brown-
out of sufficient magnitude) of more than one half mains line cycle and less than one whole cycle in duration.
9. TYPICAL APPLICA TIONS
The 6125A is essentially three stereo amplifiers in one chassis, each with dual stereo, dual mono, and bridged mono capabilities, while the 4200A is two stereo amplifiers (four channels), but with more power per chan­nel than the 6125A. Input connections are hard-wired with two-piece Euroblock connectors, while speaker outputs are wired to four position screw terminal blocks. Note: The 6125A is used for the following application details, but
the 4200A is used in a similar fashion, to a maximum of four channels.
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
s
9.1 Six Channel Setup
Six Channel Setup
Input Section: Up to Six Different Inputs Stereo/Mono Switches - Out Dual Bridge Switches - Out Levels Controls - Used Per Input Channel
! " # $
Up To Six Different Amplifier Inputs
(dual stereo)
Possible Applications: Multiple Zone Systems Three Pairs Of Studio Monitors Multiple Stage Monitors 25V Distributed Systems (6125A Only)
Outputs
! " # $
Speaker Outputs
Minimum Speaker Load Per Channel = 4
- Up To Six Different Outputs
Multi-Media Systems Surround Sound Three Way Biamplification Stereo Triamplification
9
9.2 Dual Mono Setup
Dual Mono Setup
Input Section: Up to Three Different Inputs Stereo/Mono Switches - In Dual Bridge Switches - Out Levels Controls - Only Channels 1, 3, or 5 Used
! #
Amplifier Inputs
(An Input Can Be Parallel Connected
To Other "Non-Partner" Channels by
Hard-Wire Jumping the Euroblock Connectors)
Possible Applications: Multiple Zone Systems Three Different Stage Monitor Mixe Dual-Mono FOH Tri-Amplification
Outputs
! " # $
Channels 1 & 2
From Channel 1 Input
Minimum Speaker Load Per Channel = 4
Channels 3
From Channel 3 Input
4
&
From Channel 5 Input
Channels 5
6
&
9
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
)
9.3 Bridged Mono Setup
Bridged Mono Setup
Input Section: Up to Three Different Inputs Stereo/Mono Switches - In Dual/Bridge Switches - In Levels Controls - Only Channels 1, 3, or 5 Used
! #
Amplifier Inputs
Possible Applications: 70 Volt Constant Voltage Systems (6250 Only Subwoofers High Powered Monitors High Powered Full Range PA Speakers
Outputs
Bridged Channels 1 & 2
From Channel 1 Input
Minimum Speaker Load Per Bridged Channel Pair = 8
Bridged Channels 3 & 4
From Channel 3 Input
Bridged Channels 5 & 6
From Channel 5 Input
9
9.4 Typical PA Setup
! #
Subwoofer
Input
(Bridged Mono)
"
Full Range
Inputs
(Dual Stereo)
Monitor
Input
(Dual Mono)
Typical PA Setup
Subwoofer
Bridged Output
8
Minimum
9
Outputs
Dual Full Range
Outputs
49 Min/Channel
Separate Monitor
Outputs
49 Min/Channel
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
10. DESIGN THEORY
The 6125A and 4200A amplifiers are based on stereo driver modules that use digital processing to gener­ate a spread-spectrum switching pattern between about 200KHz and 1.5MHz, depending on input signal ampli­tude and frequency. This overcomes the self-limiting and inherent weakness in traditional class D fixed-frequency PWM amplifiers, and produces an output with THD+N numbers comparable to class A and class AB linear ampli­fiers. (see Specification Notes at end of this section)
In the 6125A and 4200A, the input signal is re­ceived by a single operational amplifier configured as a difference amplifier to reduce common-mode effects from sources located at a distance. This difference amplif ier has a gain of 2.74 which allows the use of less gain later in the system, improving overall system noise performance.
The amplified signal, based on the position of vari­ous selector switches, either bypasses or is processed by a two-pole high-pass filter with rolloff at 50Hz, and then passes through the attenuating potentiometer. The attenu­ated signal is buffered and passed to the amplifier module along with a zero-volt reference.
The amplifier module receives the atten uated sig­nal with a unity gain differential amplifier to eliminate com­mon-mode interference picked up within the amplifier chassis. The signal is then added to a small DC offset sig­nal opposite in polarity to any DC offset on the output bridge and adjusted by the digital processing module as described above. The digital processing module, which also generates FET drive signals, has a v oltage gain of 11.7 for a total system voltage gain of 32. The drive signals generated by the processing module are fed to a pair of high-current MOSFET transistors, and the switched out­put of these transistors is filtered and applied to the speaker outputs. Fault conditions such as overvoltage, undervoltage, and output overcurrent are measured by the module and therefore affect a stereo pair of channels re­gardless of whether the fault actually exists on both chan­nels processed in the module. Since every action applied to protect the digital processing module affects both chan­nels being processed, other fault conditions are not sepa­rated by channel, but rather by amplifier module.
Specification Notes: Due to its spread spectrum out- put switching pattern, the output signal of a
6125A or 4200A
amplifier contains significant dynamic frequency content* far
outside the audio band, which makes no difference to audible performance, but which makes heavily bandwidth-limited** mea­surement of amplifier noise and distortion characteristics man­datory.
*variable 200KHz to 1.5MHz
**greater than 48dB/octave above 22kHz
11. TROUBLESHOO TING TIPS
11.1 No A udio Output
1.) Power LED not lit:
Line fuse is blown or power outlet is dead. IF LINE FUSE IS BLOWN, REPLACE ONLY WITH SAME TYPE AND RATING FUSE.
2.) Power LED is lit but Protect LEDs stay on:
Amp module is in protect mode. Speakers have been disconnected from amplifier output and connected to ground until the protect fault is corrected. See section 8 for a complete explanation of protect fault conditions. Out­put overcurrent, overvoltage and undervoltage faults will reset in about eight seconds once the fault condition is re­moved, while excessi v e DC offset or high frequenc y faults take about 30 seconds to reset.
Speaker Impedance: The 6125A or 4200A may
go into self-protect at high output levels if the actual speaker load impedance is much less than 4 ohms. To cal­culate speaker impedance for a given combination of di­rect-coupled speakers, use Ohm's law as applied to series and/or parallel resistor networks, where each speaker (for this purpose) can be thought of as a single resistor, using DC resistance measurements.
Simply stated, speakers connected in series will add together their impedance. Conversely, two speakers con­nected in parallel will result in half the impedance, three parallel speakers a third the impedance, four speakers a fourth, and so on, assuming the speaker impedances are all the same. Don't use mismatched impedances in parallel. When using paralleled speakers, the available amplifier power for that channel is evenly divided among speakers, so 100 watts driving two parallel speakers of equal imped­ance provides 50 watts to each speaker, etc.
3.) Thermal LED and Protect LEDs stay on:
Amp module is in thermal protect mode and needs to cool. The fan will continue to run while in thermal pro­tect, and other modules will continue to function. See sec­tion 8.4 for details.
4.) Power LED lit but no Signal LED activity
There is no input signal applied or input level con­trols are turned down.
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
11.2 Distorted Sound
1.) Clip LED is flashing regularly
Amplifier is being overdriven. Turn down the in­put level control, or reduce the output level from the sig­nal source.
2.) Clip LED is not flashing at all
Amplifier input signal may be exceeding input headroom, which is greater than +12dBu, or 3.4V rms (measured using continuous 1kHz sine wave). Incoming signal level higher than +12.8 dBu will cause distortion in the amplifier. Turning down the input level controls will
not eliminate distortion if the input headroom is exceeded.
Turn down the output level of the device driving the am­plifier instead.
Additionally, an input signal may already be dis­torted before it gets to the amp. Check to see if a piece of equipment in the signal chain before the amp is clipping. For best performance, the amplifier should be operated with input levels fully CW. Also check for damaged speaker drivers that could cause distorted sound.
11.3 Hum or Buzz Noise
Be sure that the power cord’s 3-prong plug is con­nected to a properly earth-grounded outlet. Lifting the grounding third prong may not improve hum or buzz and can create a potential shock hazard.
Hum is usually caused by ground currents flow­ing between different pieces of equipment. Ground cur­rents can be minimized by using a single point AC ground for the sound system, and by using balanced connections with quality cable throughout the audio path.
Buzz, as well as certain audible high frequency tones, can be caused by environmental emissions such as lighting dimmers, neon lights, or computer equipment. Use balanced connections, and try moving the amplifier, wir­ing, lighting, or other equipment to different locations to isolate the source of the noise.
Sections 3.3, 5.3, 7.1, and 7.2 further discuss is­sues related to grounding and noise problems.
12. DIMENSIONS
13.5" (344)
16.9" (430)
18.5" (470)
2.25" (57.2)
13.2" (335)
1.25"
(31.8)
14
2.25"
(57.2)
4.75" (121)
5.19" (132)
19" (483)
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
13. SPECIFICATIONS
*Power Output
(Maximum A verage Power, 0.1% THD, 1KHz)
Rated Per Channel, Two Channels Driven
6125A 4200A
4 ohm: 250 Watts RMS 400 Watts RMS 8 ohm: 150 Watts RMS 275 Watts RMS Mono Bridged (1 Channel) 8 ohm: 500 Watts RMS 800Watts RMS
Rated Per Channel, All Channels Driven
6125A 4200A
4 ohm: 250 Watts RMS† 400 Watts RMS† 8 ohm: 150 Watts RMS 275 Watts RMS Mono Bridged (3 channels) 8 ohm: 500 Watts RMS 800Watts RMS
(Maximum Average Power, 0.2% THD, 20Hz-20KHz) Rated Per Channel, All Channels Driven
6125A 4200A
8 ohm: 130 Watts RMS 230 Watts RMS
Input Impedance: 10K ohm balanced, 37K ohm unbal­anced
High Pass Filter: 50Hz, 12dB/octave
**Total Harmonic Distortion (20Hz - 20KHz @ 8 ohms):
<0.2%
**IMD
(SMPTE 60Hz/7KHz 4:1) @ 8 ohms: <0.2% (throughout power range) (IHF) @ 8 ohms: <0.1% (throughout power range)
**Hum and Noise: -100dB from full output (A-weighted)
Full Power Input Sensitivity:
6125A 4200A
1.08V RMS (2.9dBu) 1.47V RMS (5.6dBu)
Typical Idle Current
6125A 4200A
120V: 0.81A 120V: 0.9A 240V: 0.42A 240V: 0.5A
Current with Typical A udio Program Material (4 ohm load
- all Channels)
6125A 4200A
120V: 6.5A 120V: 7.0A 240V: 3.3A 240V: 3.5A
Connections
Input: Euroblock
Output: Screw Terminal Block
Cooling: F orced Air , Thermal Sensitiv e 3-Speed Fan, Front
Inlet/Rear Outlet
Dimensions: 19” (483mm) L x 5.25” (133mm) H x 16.5”
(419mm) D
Construction: 14 Gauge All-Steel Chassis
Weight 6125A 4200A
Shipping 56lbs. (25.5Kg) 53lbs. (24Kg)
Net 49lbs. (22.3Kg) 46lbs. (21Kg)
Specification conditions: 120VAC mains at 60Hz, 25° C
* Continuous power limited by power line capacity
**Non-conventional amplifiers require bandwidth limiting
for all distortion and noise measurements.
† Signal peaks in audio programming may trigger protec­tion circuitry at low line voltages. Specifications are subject to change or improvement without notice.
14. WARRANTY INFORMA TION
The unit you have just purchased is protected by a limited five-year warranty . For warranty service or to obtain a return RMA number, please call Altec Lansing technical services at 405-848-3108. Fill out the informa­tion below for your records.
Frequency Response:
8 ohm: ±0.5dB 20Hz-20kHz 4 ohm: ±1.5dB 20Hz-20kHz
Voltage Gain: 32X (30.1dB)
Crosstalk: < -80dB (20Hz - 1KHz)
Signal Present Signal Sensitivity: 13mV RMS (-35.5dBu)
Power Requirement:
110-125VAC, 220 - 250VAC 50-60Hz
Serial Number _________________________________ Dealer ________________________________________ Date of Purchase _______________________________ Dealer’s Address _______________________________ Dealer’s Phone ________________________________ Salesperson ___________________________________
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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier
Altec Lansing PrAltec Lansing Pr
Altec Lansing Pr
Altec Lansing PrAltec Lansing Pr
1000 W. Wilshire Blvd. Suite 362
A division of Altec Lansing Technologies Inc, Milford PA 18337-0277 Made In USA
Printed in USA 6125A-0 0503
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