Legacy Car Audio LA-878, LA-778, LA-1478, LA-978, LA-2078 User Manual

MANUFACTURER’S LIMITED TWO YEAR

LEGACY SOUND CORP. warrants this unit to be free from defective material or workmanship and will repair or

replace this unit or any part thereof if it proves defective in normal use or service within two (2) years from

Our obligation under this warranty is limited to repairing or replacing, at our discretion, the defective instrument

or any part thereof when it is returned, transportation prepaid to the Legacy Service Center at the address

below. This warranty will be considered void if the unit has been tampered with, improperly serviced, subjected

to abuse or misuse or if installed in a commercial vehicle. This warranty does not cover accidental damage.

When returning this unit for service, please include $15.00 for return postage and handling. Send your unit to:

WARRANTY

the date of original purchase.

IMPORTANT: Pack carefully in original carton if possible. We are not
responsible for damage incurred in returning items for repair. A letter
stating your exact street address, daytime phone number, and the
problem you are experiencing should be included. You must also enclose
a copy of the original receipt as proof of date of purchase.

FOR YOUR PROTECTION

Completely and immediately mail the Product Registration Card

so that we may contact you directly in the event a safety

notification is issued in accordance with the 1972 Consumer

Product Safety Act, or for other reasons Legacy may deem

TECHNICAL SUPPORT HOTLINE

Our technical department will gladly answer any questions
you may have about our products. They cannot, however

tell you the status of a repair, or handle other customer

service situations.

1-800-934-2277

Monday through Thursday, 9AM to 5PM
Friday 9AM to 2PM Eastern.

necessary.

LEGACY SERVICE CENTER

1600 63rd Street

Brooklyn, NY 11204

LA-478
LA-578
LA-678

LA-778
LA-878
LA-978

LA-1478

LA-1878
LA-2078
LA-2278
LA-2478

WWW.legacycaraudio.com

Congratulations

on your purchase of a new

Legacy American Series 2 amplifier !

Legacy American Amplifier Features

LA-478/578/678/778/878/978
1478/1878/2078/2278 also feature:

• Soft turn on/off circuit

• Variable gain control

• Remote turn on/off

• Hi/low level inputs

• Power on LED indicator

• LED protection indicator

• Fully adjustable electronic crossover network

• Remote control Bass boost ( 0 – +18dB @ 60Hz )

• 2 ohm stereo stable

• Bridgeable into 4 ohms

• MOSFET PWM power supplies

Legacy amps are some of the most advanced car amplification products
available. These quality audio products are designed and engineered to afford
you years of uncompromised musical service. Legacy has utilized the latest
electronic technologies in order to deliver a superb listening experience.

This innovative system has been designed utilizing a 12 V DC Negative Ground
power supply . The Legacy American Series 2 amps incorporate two to eight
MOSFETS in the different models.

This design produces enough available voltage to supply the main amplifier
sections, and still have a huge amount of reserve voltage for peak “high
demand” situations.

The Legacy line has been designed to ensure adequate headroom for even
the most demanding peaks and dynamic ranges found on today’s CD’s and
recordings. Used properly, these amplifiers will provide you with years of
listening pleasure.

USER MANUAL

table of contents

SPECIFICATIONS

1~2

LA-478/578/778/978/1478/1878/2078/2278

3

FEATURES & CONTROLS
LA-678/878 FEATURES & CONTROLS

4

LA-2478 FEATURES & CONTROLS

5

ELECTRICAL WIRING, INSTALLATION & SETUP

6

2 CH STEREO INPUT CONNECTIONS

7

4 CH STEREO INPUT CONNECTIONS

8

BRIDGED INPUT CONNECTIONS

9

BASIC STEREO SPEAKER CONNECTIONS

11

MONO-BRIDGED SPEAKER CONNECTIONS

12

MONO BLOCK INPUT & SPEAKER CONNECTIONS

13

TROUBLESHOOTING

14

Specifications

OUTPUT POWER

RMS @ 4 OHMS
RMS @ 2 OHMS
MAX OUTPUT 
BRIDGE MODE

FREQUENCY RESPONSE
INPUT IMPEDANCE

LOW LEVEL INPUTS
HIGH LEVEL INPUTS

INPUT SENSITIVITY

LOW LEVEL INPUTS
HIGH LEVEL INPUTS

POWER SUPPLY VOLTAGE
MATCHING SPEAKER IMPEDANCE

STEREO MODE
BRIDGED MODE

MAXIMUM CURRENT DRAW
DIMENSIONS, W x H x L, inches

(mm)

NET WEIGHT, LBS (KG)

LA-478

2CH amplifier

2 X 40W
2 X 60W
2 X 300W
1 X 600W

10Hz-30 kHz

10 k-Ohms
100 Ohms

250 mV

2.5V

14.4 VDC/NEG GD (10.5-16V)

2-4 OHMS
4-8 OHMS

15 A

12.2 X 2 X 8.25

(309 X 53 X 209)

5.2(2.37)

LA-578

2CH amplifier

2 X 50W
2 X 75W
2 X 400W
1 X 800W

2-4 OHMS
4-8 OHMS

15 A

12.2 X 2 X 9.25

(

309 X 53

5.9(2.67)

X 235)

LA-678

4CH amplifier

4 X 35W
4 X 55W
4 X 250W
2 X 250W+500W

OR 2 X 500W

2-4 OHMS
4-8 OHMS

20 A

12.2 X 2 X

(

309 X 53

7.7(3.5)

12

X 305)

LA-778

2CH amplifier

2 X 75W
2 X 125W
2 X 500W
1 X 1000W

2-4 OHMS
4-8 OHMS

20 A

12.2 X 2 X

(

309 X 53

7.6(3.46)

12

X 305)

LA-878

4CH amplifier

4 X 50W
4 X 60W
4 X

400W

2 X 400W+800W

OR

2 X 800W

2-4 OHMS
4-8 OHMS

40 A

12.2 X 2 X

(

309 X 53

9.1(4.4)

15

X 381)

1

Features and Specifications

specs

Legacy American Amplifier Features

LA-2478 also feature:

· Mono Block Subwoofer Amplifier

· 2 Ohm Stable

· MOSFET Power Supply

· Gold Plated RCA Inputs for Line Input & Bypass Output.

· Gold Plated Terminals for Speaker Output and Power Input.

· Thermal, Overload and Short Protection

· Variable Sub-sonic Filter (15Hz~40Hz, 24dB/Octave)

· Variable Low-pass Filter (20Hz~250Hz, 24dB/Octave)

Specifications

OUTPUT POWER

RMS @ 4 OHMS
RMS @ 2 OHMS
MAX OUTPUT 
BRIDGE MODE

FREQUENCY RESPONSE
INPUT IMPEDANCE

LOW LEVEL INPUTS
HIGH LEVEL INPUTS

LA-978

2CH amplifier

2 X 100W
2 X 150W
2 X 600W
1 X 1200W

10Hz-30 kHz

10 k-Ohms
100 Ohms

LA-1478

2CH amplifier

2 X 125W
2 X 200W
2 X 800W
1 X 1600W

LA-1878

2CH amplifier

2 X 150W
2 X 225W
2 X 1000W
1 X 2000W

· Phase Control 0-180 degree

· Remote Bass Control

· Input Impedance : 10K Ohms

· Soft Turn On/Off

· Advanced Protection Circuitry

· S/N Ratio:>90dB

LA-2078

2CH amplifier

2 X 200W
2 X 300W
2 X 1200W
1 X 2400W

LA-2278

2CH amplifier

2 X 300W
2 X 450
2 X 200

W
0W

1 X 4000W

LA-2478

Mono channel amplifier

200W mono
335W mono
2000W mono

20-250Hz( 3dB)

10 k-Ohms
100 Ohms

Speaker Terminals1

These terminals are 14K Gold plated for high conductivity
and minimum impedance loss. The terminals face
upwards for easy wiring in tight situations.

Fuse

2

Protects the amplifier as well as the automobile electrical
system from short circuit conditions.

Power Supply Terminals

3

Input Level Control

4

Use this control to match the output of the head unit
to the amplifier. If distortion is present, reduce the
setting of this control.

5

Crossover Mode Switch

In a full range system, set this to FULL. If the amp is
being used to power a crossover system, set to either
HPF or LPF as needed.

Bass Boost Control

6

Allows you to increase the bass signal level sent to the
speakers

Low Pass Control

7

Permits you to adjust the crossover frequency from 35
Hz to 400 Hz to suit the subwoofers

High Pass Control

8

Permits you to adjust the crossover frequency from
80 Hz to 2.5 kHz to suit the tweeters

High Level Input (Low Impedance)

9

Use these if your car stereo does not have
RCA output jacks: connect the speaker output from
the head unit to these inputs

Low Level Input (High Impedance)

10

This unit is provided with gold-plated RCA input
jacks. Using RCA-RCA type patch cords, connect
these inputs to the RCA outputs from your head
unit.

Power LED Indicator

11

This LED is illuminated when the REMOTE ON
system is turned on.

3

INPUT SENSITIVITY

LOW LEVEL INPUTS
HIGH LEVEL INPUTS

POWER SUPPLY VOLTAGE
MATCHING SPEAKER IMPEDANCE

STEREO MODE
BRIDGED MODE

MAXIMUM CURRENT DRAW
DIMENSIONS, W x H x L, inches

(mm)

NET WEIGHT, LBS (KG)

specs

Features and Specifications

250 mV

2.5V

14.4 VDC/NEG GD (10.5-16V)

2-4 OHMS
4-8 OHMS

30 A

12.2 X 2 X

(

309 X 53

13.5

X 343)

8.2(3.73)

2-4 OHMS
4-8 OHMS

30 A

12.2 X 2 X

(

309 X 53

15

X 381)

8.8 (4.0)

2-4 OHMS
4-8 OHMS

40 A

12.2 X 2 X

(

309 X 53

17

X 432)

10.1 (4.62)

2-4 OHMS
4-8 OHMS

50 A

12.2 X 2 X

(

309 X 53

19

X 482)

11.4 (5.2)

2-4 OHMS
4-8 OHMS

70 A

12.2 X 2 X

(

309 X 53

21

X 532)

12.8 (5.8)

250 mV
4V

14.4 VDC/NEG GD
(10.5-16V)

2 OHM
STABLE

40 A

12.2 X 2 X

(

309 X 53

12

X 305)

7.3 (3.34)

12

Protection LED Indicator

The protection circuitry in the amp will disable it if it
senses an input overload, speaker short circuit, or
thermal overload conditions. Should this occur, the
PROTECT LED will be illuminated. At that time, it is
important that you check to determine what has caused
the protection circuitry to become activated.

If the amp shut off because of a thermal overload,
allow it to cool down before attempting to restart.

If the shutdown occured because of an input overload,
or speaker short circuit, be sure to correct these
conditions before attempting to restart the amp.

To reset the amp, turn the REMOTE power off and on
again.

13

Remote Bass Boost

Plug in the Remote Bass Boost Control wire in here.

LA-478/578/778/978/1478/1878/2078/2278

Features and Controls

1

Speaker Terminals

These terminals are 14K Gold plated for high conductivity
and minimum impedance loss. The terminals face
upwards for easy wiring in tight situations.

2

Fuse

Protects the amplifier as well as the automobile electrical
system from short circuit conditions.

Power Supply Terminals

3

Input Level Control

4

Use this control to match the output of the head unit
to the amplifier. If distortion is present, reduce the
setting of this control.

5

Crossover Mode Switch

In a full range system, set this to FULL. If the amp is
being used to power a crossover system, set to either
HPF or LPF as needed.

Bass Boost Control

6

Allows you to increase the bass signal level sent to the
speakers

Low Pass Control

7

Permits you to adjust the crossover frequency from 35
Hz to 400 Hz to suit the subwoofers

High Pass Control

8

Permits you to adjust the crossover frequency from
80 Hz to 2.5 kHz to suit the tweeters

High Level Input (Low Impedance)

9

Use these if your car stereo does not have
RCA output jacks: connect the speaker output from
the head unit to these inputs

Low Level Input (High Impedance)

10

This unit is provided with gold-plated RCA input
jacks. Using RCA-RCA type patch cords, connect
these inputs to the RCA outputs from your head
unit.

Power LED Indicator

11

This LED is illuminated when the REMOTE ON
system is turned on.

12

Protection LED Indicator

The protection circuitry in the amp will disable it if it
senses an input overload, speaker short circuit, or
thermal overload conditions. Should this occur, the
PROTECT LED will be illuminated. At that time, it is
important that you check to determine what has caused
the protection circuitry to become activated.

If the amp shut off because of a thermal overload,
allow it to cool down before attempting to restart.

If the shutdown occured because of an input overload,
or speaker short circuit, be sure to correct these
conditions before attempting to restart the amp.

To reset the amp, turn the REMOTE power off and on
again.

1 3

Remote Bass Boost

Plug in the Remote Bass Boost Control wire in here.

1

Speaker Terminals

These terminals are 14K Gold plated for high conductivity
and minimum impedance loss. The terminals face
upwards for easy wiring in tight situations.

Fuse

2

Protects the amplifier as well as the automobile electrical
system from short circuit conditions.

Power Supply Terminals

3

Input Level Control

4

Use this control to match the output of the head unit
to the amplifier. If distortion is present, reduce the
setting of this control.

5

Phase Shift Switch

Allows you to change the phase of your subwoofer
from 0 degree to 180 degrees to help compensate from
timing difference between drivers.

High Pass Subsonic Filter

6

Adjustable from 15Hz to 40Hz with a slope of 24dB per
octave.This allows for the attenuation of frequencies that
are mostly inaudible and cause unnecessary strain on the
amplifier.

Crossover Low Pass Filter

7

Adjustable from 20Hz to 250Hz with a slope of 24dB per
octave.This allows for the adjustment of the upper point
of the frequency bandwidth and the respective subwoofer.

Low Level Input (High Impedance)

8

This unit is provided with gold-plated RCA input
jacks. Using RCA-RCA type patch cords, connect
these inputs to the RCA outputs from your head
unit.

Low Level Output (High Impedance)

9

This unit is provided with gold-plated RCA Output jacks.
Using RCA-RCA type patch cords, connect these Outputs
to the RCA Inputs for your anyther amplifier.

Protection LED Indicator

10

The protection circuitry in the amp will disable it if it
senses an input overload, speaker short circuit, or
thermal overload conditions. Should this occur, the
PROTECT LED will be illuminated. At that time, it is
important that you check to determine what has caused
the protection circuitry to become activated.

If the amp shut off because of a thermal overload,
allow it to cool down before attempting to restart.

If the shutdown occured because of an input overload,
or speaker short circuit, be sure to correct these
conditions before attempting to restart the amp.

To reset the amp, turn the REMOTE power off and on
again.

Power LED Indicator

11

This LED is illuminated when the REMOTE ON
system is turned on.

12

Remote Bass Boost

Plug in the Remote Bass Boost Control wire in here.

5

LA-678/878

Features and Controls

LA-2478

Features and Controls

Making Power Connections

1. Connect the +12V terminal directly to the car battery (+) terminal.

2. Connect the GROUND terminal directly to the car battery (-) terminal
OR to a good clean, paint-free chassis ground point.

3. To ensure a good ground, and to prevent “motor-boating” noise in the
system, make an additional connection from the car battery (-) terminal
to the chassis of the stereo unit, using 12 gauge minimum wire.

4. Connect the REMOTE terminal to an external switch for positive 12V
turnon-off. This may be connected to the head unit power antenna lead.

Installation Precautions

This amplifier comes complete with all mounting harware required. Please remember that this is a high-power unit, which generates considerable electrical energy and
heat. Therefore, be sure to install the unit in a place with sufficient airflow, a minimum of dust, and no moisture. Allow enough space around the cooling fins to permit
reasonable airflow and cooling.

• Before you drill or cut any holes, investigate your car’s layout very carefully. Take care when you work near the gas tank, fuel lines, hydraulic line and electrical wiring.

• Do not operate the amplifier when it is unmounted. Attach all audio system components securely within the automobile to prevent damage, especially in an accident.

• Do not mount this amplifier so that the wire connections are unprotected or in a pinched condition, or likely to be damaged by nearby objects. Be sure to select a
location inside your vehicle which has adequate ventilation.

• Before making or breaking power connections in your system, disconnect the vehicle battery. Confirm that your head unit or other equipment is turned off while
connecting the input jacks and speaker terminals.

• If you need to replace the power fuse, only replace it with a fuse identical to that supplied with the system. Using a fuse of a different type or rating may result in
damage to your system which isn’t covered by the manufacturer’s warranty.

Electrical Connections

(all models)

to remote

turn-on

+12V

head unit

12V battery

Low Level Stereo Input Connection

head unit

L/R audio outputs

High Level Stereo Input Connection

PLEASE NOTE! If using high level
inputs, do not use the low level
RCA inputs at the same time!

LA­LA­LA­LA­LA­LA­LA­LA-

2CH AMPS

478
578
778

978
1478
1878
2078
2278

7

Setting Up and Turning On Your New Amplifier

After all electrical connections have been made, and physical installation is complete, turn on your stereo and listen for the amplifier to turn on. If there are any unusual
noises from the speakers, turn the stereo off and recheck ALL wiring.

Assuming the amplifier turn on normally, you may have to adjust the LEVEL control(s) to match the output levels from your head unit. Follow these steps:

1. Set the volume control on your head unit to about the 2/3 position.

2. Adjust the amplifier LEVEL control(s) to an average listening position.

3. Turn the head unit volume all the way down, and listen for background noise.

4. Start your vehicle, and again, listen for background noise.

5. By fine tuning the LEVEL control(s), you can reduce background and engine noise, if present.
These adjustments should only be made once. After that, use the head unit volume control to adjust the system volume, not the LEVEL control(s).

CAUTION: Never turn the LEVEL control(s) up any higher than you need to get clear sound at 2/3 volume on the head unit.

Electrical Wiring and Installation

head unit

L RL R

from speaker terminals

wiring harness

orange
black
black

orange

inputs

Input Connections

LA-

678

LA-

478

LA-

4CH AMPS

878

Low Level 4 CH Stereo Input

from 2 CH Audio Source

Right Output

Left Output

Y adaptors

head unit

to a second

amplifier

Y adaptors

Bridged Input Connection

head unit

LA­LA­LA­LA­LA­LA­LA-

2CH AMPS

LA­LA-

4CH AMPS

578

778

978
1478
1878
2078
2278

9

678
878

inputs

Input Connections

Low Level 4 CH Stereo Input

from 4 CH Audio Source

L + R Front Outputs

L + R Rear Outputs

head unit

4 CH Bridged Input

from 2 CH Audio Source

CH1+2 = Left Channel

CH3+4 = Right Channel

Left Output

Right Output

Y adaptors

head unit

inputs

Input Connections

LA-

678

LA-

478

LA-

4CH AMPS

878

orange
black

black
orange

L R

REAR FRONT

wiring harness

L R

head unit

orange
black

black
orange

High Level 4 CH Stereo Input

from 4CH Audio Source
floating ground connection

LEFT speaker RIGHT speaker

Basic Stereo Output

LA­LA­LA­LA­LA­LA­LA-

2CH AMPS

LA­LA-

4CH AMPS

578

778

978
1478
1878
2078
2278

11

678
878

inputs

Input Connections

orange
black

black
orange

REAR FRONT

head unit

RL R L

orange
black

black
orange

High Level 4 CH Stereo Input

from 4CH Audio Source
common ground connection

L

speakers

FRONT

R L

Basic 4CH Output

R

REAR

speakers

Speakers

Speaker Connections

LA­LA­LA-

478
578
778

Low Level Stereo Input Connection

LA-

MONO CHANNEL

2478

AMPS

LA­LA­LA­LA­LA-

2CH AMPS

LA­LA-

4CH AMPS

978
1478
1878
2078
2278

678
878

MINIMUM

SPEAKER

IMPEDANCE

speaker

speakers

MINIMUM

L R

SPEAKER

IMPEDANCE

4 OHMS!

4 OHMS!

Bridged Mono Output

2 CH Mono-Bridged Output

head unit

subwoofer

L/R Audio

Outputs

Speaker Output Connection

MINIMUM

SPEAKER

IMPEDANCE

2~4 OHMS!

TO SATELLITE AMPLIFIER
LINE INPUT

13

L

Speakers

Speaker Connections

R

Mono

Subwoofer

speakers

MINIMUM

SPEAKER

IMPEDANCE

4 OHMS!

2 CH Stereo plus
Mono-Bridged
Subwoofer Output

inputs/Speaker

Input Connections/Speaker Connection

Amplifier will not power up.

• Check for good ground connection.

• Check that remote DC terminal has at least +12v DC.

• Check that there is battery power on the + terminal.

• Check all fuses.

• Check that Protection LED is not lit. If it is lit, shut off amplifier
briefly and then repower it.

High hiss or engine noise (alternator whine) in
speakers.

• Disconnect all RCA inputs to the amplifier(s) – if hiss/noise
disappears, then plug in the component driving the amplifier
and unplug its inputs. If hiss/noise disappears, go on until the
faulty/noisy component is found.

• It is best to set the amplifier's input level as insensitive as
possible. The best subjective S/N ratio is obtainable this way .
T ry to drive as high a signal level from the head unit as possible.

Protection LED comes on when the amplifier is
powered up.

• Check for shorts on speaker leads.

• Check that the volume control on the head unit is turned
down low.

• Remove speaker leads, and reset the amplifier. If the
Protection LED still comes on, then the amplifier is faulty.

STOP

4 ohm

2 -c hannel Amplifier

(Operating in Stereo)

YES! NO!

Two 4-ohm speakers, wired in stereo,
will present a 4-ohm load to each
channel of the amplifier. Most two­channel amplifiers will work well in this
configuration.

sound around, Inc.

1600 63rd street. brooklyn. ny 11204

4 ohm

STOP

4 ohm

2 -c hannel Amplifier

(Operating in

Bridged Mono)

4 ohm

Two 4-ohm speakers, wired in parallel
to a bridged two-channel amplifier.
will present a 2-ohm mono load to the
amplifier. MOST TWO-CHANNEL

AMPLIFIERS DO NOT SUPPORT 2-OHM
MONO OPERATION! AMPLIFIER DAMAGE
COULD RESULT!

15

Amplifier(s) gets very hot.

• Check that the minimum speaker impedance for that model
is correct.

• Check for speaker shorts.

• Check that there is good airflow around the amplifier. In
some applications, an external cooling fan may be required.

Distorted sound

• Check that the Level control(s) is set to match the signal
level of the head unit.

• Check that all crossover frequencies are properly set.

• Check for shorts on the speaker leads.

High squeal noise from speakers.

• This is almost always caused by a poorly-grounded RCA
patch cord.

troubleshooting

4 ohm

4 -c hannel Amplifier

(Operating in Stereo)

YES!

Four 4-ohm speakers, wired in stereo,
will present a 4-ohm load to each
channel of the amplifier. Most four­channel amplifiers will work well in this
configuration.

4 ohm

4 ohm

4 ohm

4 -c hannel Amplifier

(Operating in

Bridged Mono)

NO!

Four 4-ohm speakers, wired in parallel
to a bridged four-channel amplifier,
will present a 4-ohm mono load to the
amplifier. MOST FOUR-CHANNEL

AMPLIFIERS DO NOT SUPPORT 2-OHM
MONO OPERATION! AMPLIFIER DAMAGE
COULD RESULT!

Troubleshooting

4 ohm

4 ohm

4 ohm

4 ohm