Legacy Car Audio la970, LA370, LA470, LA2070, LA570 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 the

W ARRANTY

date of original purchase.

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:

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

LA370
LA470
LA570
LA670
LA770
LA870
LA970
LA1470
LA1870
LA2070

HIGH SPEED

CAR AMPLIFIER

www.legacycaraudio.com

Congratulations

on your purchase of a new

Legacy Red Series 2 amplifier!

Legacy Red Series 2 Amplifier Features

all amps feature:

• Polished chrome finish w/plexiglass panel

• Soft turn on/off circuit

• Variable gain control

• Remote turn on/off

• Hi/low level inputs

• Power on LED 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

• LED protection indicator

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 Red 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

LA370/LA470/570/770/970/1470/1870/2070

2

FEATURES & CONTROLS
LA670/870 FEATURES & CONTROLS

3

ELECTRICAL WIRING, INSTALLATION & SETUP

4

2 CH STEREO INPUT CONNECTIONS

5

4 CH STEREO INPUT CONNECTIONS

6

BRIDGED INPUT CONNECTIONS

8

BASIC STEREO SPEAKER CONNECTIONS

9

MONO-BRIDGED SPEAKER CONNECTIONS

10

TROUBLESHOOTING

11

WARRANTY

12

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)

LA370

2CH amplifier

2 X 40W
2 X 60W
2 X 250W
1 X 500W

10-30 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

10.4 X 2.6 X 10.5

(264 X 66 X 268)

LA470

2CH amplifier

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

2-4 OHMS
4-8 OHMS

15 A

10.4 X 2.6 X 12

(264 X 66 X 304)

LA570

2CH amplifier

2 X 50W
2 X 85W
2 X 400W
1 X 800W

2-4 OHMS
4-8 OHMS

15 A

10.4 X 2.6 X 12.7

(264 X 66 X 322)

LA670

4CH amplifier

4 X 35W
4 X 55W
4 X 250W
2 X 500W
(2 X 250W+1X500W)

2-4 OHMS
4-8 OHMS

20 A

10.4 X 2.6 X 14

(264 X 66 X 358)

LA770

2CH amplifier

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

2-4 OHMS
4-8 OHMS

20 A

10.4 X 2.6 X 14

(264 X 66 X 358)

LA870

4CH amplifier

4 X 50W
4 X 85W
4 X 400W
2 X 800W
(2 X 400W+1X800W)

2-4 OHMS
4-8 OHMS

30 A

10.4 X 2.6 X 15.5

(264 X 66 X 394)

LA970

2CH amplifier

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

2-4 OHMS
4-8 OHMS

30 A

10.4 X 2.6 X 15.5

(264 X 66 X 394)

LA1470

2CH amplifier

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

2-4 OHMS
4-8 OHMS

30 A

10.4 X 2.6 X 16.2

(264 X 66 X 412)

LA1870

2CH amplifier

2 X 150W
2 X 230W
2 X 900W
1 X 1800W

2-4 OHMS
4-8 OHMS

40 A

10.4 X 2.6 X 17

(264 X 66 X 430)

LA2070

2CH amplifier

2 X 230W
2 X 350W
2 X 1200W
1 X 2400W

2-4 OHMS
4-8 OHMS

40 A

10.4 X 2.6 X 19

(264 X 66 X 484)

NET WEIGHT, LBS (KG)

7.3 (3.3)

8.4 (3.7)

8.8 (4)

9.7 (4.4)

9.6 (4.3)

Features and Specifications

10.6 (4.8)

10.4 (4.7)

11 (5)

11.5 (5.2)

specs

13 (5.9)

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

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

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

LA970LA970

600W x 2CH

10

1212

11

13

12

9

10

54 7 8

16

2

3

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)

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.

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.

LA870LA870

400W x 4CH

3

11

13

12

9

10

54 7 8

16

2

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.

1212

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.

3

LA370/470/570/770/970/1470/1870/2070

Features and Controls

Remote Bass Boost (LA370 without)

13

Plug in the Remote Bass Boost Control wire in here.

LA670/870

Features and Controls

Remote Bass Boost

13

Plug in the Remote Bass Boost Control wire in here.

LA370

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

LA470
LA570
LA770
LA970
LA1470
LA1870
LA2070

2CH AMPS

5

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

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

R LR L

from speaker terminals

wiring harness

orange
black
black

orange

Input Connections

inputs

LA670

LA670

LA870

4CH AMPS

Left Output

Right Output

Y adaptors

head unit

Low Level 4 CH Stereo Input

from 2 CH Audio Source

orange
black
black
orange

R L

REAR FRONT

wiring harness

R L

LA870

4CH AMPS

High Level 4 CH Stereo Input

from 4CH Audio Source

floating ground connection

head unit

orange
black
black
orange

7

Input Connections

L + R Front Outputs

L + R Rear Outputs

head unit

Low Level 4 CH Stereo Input

from 4 CH Audio Source

orange
black
black
orange

High Level 4 CH Stereo Input

from 4CH Audio Source

common ground connection

head unit

LR L R

orange
black
black
orange

REAR FRONT

Input Connections

inputs

LA370

LA370
LA470
LA570
LA770
LA970
LA1470
LA1870
LA2070

2CH AMPS

LA670

to a second

amplifier

Y adaptors

head unit

Bridged Input Connection

Basic Stereo Output

LEFT speaker RIGHT speaker

LA470

LA570

LA770

LA970

LA1470

LA1870

LA2070

2CH AMPS

9

LA670

LA870

4CH AMPS

Input Connections

Left Output

Right Output

Y adaptors

head unit

4 CH Bridged Input

from 2 CH Audio Source

CH1+2 = Left Channel
CH3+4 = Right Channel

L

FRONT

speakers

R L

Basic 4CH Output

R

REAR

speakers

Speaker Connections

speakers

LA870

4CH AMPS

LA370
LA470
LA570
LA770
LA970
LA1470
LA1870
LA2070

2CH AMPS

LA670
LA870

4CH AMPS

MINIMUM

SPEAKER

IMPEDANCE

speaker

speakers

MINIMUM

L R

SPEAKER

IMPEDANCE

4 OHMS!

4 OHMS!

Bridged Mono Output 2 CH Stereo plus

Mono-Bridged

speakers

MINIMUM

SPEAKER

IMPEDANCE

L

R

Mono

Subwoofer

4 OHMS!

Subwoofer Output

TROUBLESHOOTING

Before removing your amplifier, refer to the list below
and follow the suggested procedures. Always test the

• 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.

• 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.

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

2 CH Mono-Bridged Output

Amplifier will not power up.

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

Protection LED comes on when the amplifier is
powered 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.

• 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.
Try to drive as high a signal level from the head unit as possible.

• 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.

Amplifier(s) gets very hot.

Distorted sound

High squeal noise from speakers.

LA670

LA870

4CH AMPS

11

speakers and their wires first.

Speaker Connections

troubleshooting

Troubleshooting