Legacy Car Audio LA1438 patch cord. troubleshootingTroubleshooting, Bridged Mono Output, Stop

L A 4 3 8 L A 5 3 8 L A 7 3 8 L A 9 3 8 LA1438 LA1838 LA2038

2CH AMPS

Bridged Mono Output

MINIMUM

SPEAKER

IMPEDANCE

speaker 4 OHMS!

L R

Mono

Subwoofer

speakersMINIMUM SPEAKER IMPEDANCE 4 OHMS!

L A 6 3 8

L A 8 3 8

LA1038

4CH AMPS

2 CH Stereo plus Mono-Bridged Subwoofer Output

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.

STOP

11

L A 6 3 8 L A 8 3 8 LA1038

4CH AMPS

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

Protection LED comes on when the amplifier is powered up.

4 ohm

2 -c hannel A m p l i f i e r (Operating in Stereo)

YES! 4 ohm

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

sound around, Inc.

1600 63rd street. brooklyn. ny 11204

	4 ohm
2 -c hannel Amplifier
(Operating in
Bridged Mono)
NO!	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!

2 CH Mono-Bridged Output

• 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

	speakers
	MINIMUM
L	SPEAKER	R
	IMPEDANCE
	4 OHMS!

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.

4 ohm

4 ohm

4 -c hannel Amplifier (Operating in Stereo)

4 ohm

4 ohm

4 ohm

4 -c hannel Amplifier

(Operating in

Bridged Mono)

4 ohm

Distorted sound

• Check that the Level control(s) is set to match the signal

YES! 4 ohm

NO!

4 ohm

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.

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

sound around, Inc.

1600 63rd street. brooklyn. ny 11204

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!

Speaker Connections

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

patch cord. troubleshootingTroubleshooting