J 820M (serv.man2) - JBL Audio User Guide / Operation Manual. Page 5

Part B indicates that the amplifier can
handle 4-ohm combined impedances
created by two sets of speakers. 
If only an 8-ohm rating is given, the
amp/receiver may or may not be
designed to handle 4-ohm combined
ratings.  Consult the owner’s manual
of the amp/receiver for clarification.

Thanks to their high efficiency, the
JBL J Series Loudspeakers will pro-
duce reasonable volume levels in a
room of moderate size with very little
amplifier power.  However, using a
small amplifier to obtain the desired
volume listening levels may lead to
overdriving the amplifier. This will
generate high distortion levels and
may cause damage to your loud-
speaker.  For the best performance,
an amplifier should be selected with
an output rating that is greater than
the maximum power that will be
used. This margin of reserve power
will ensure that the amplifier will not
attempt to deliver more power than
its design allows.  However, the
amplifier’s power rating per channel
must not exceed the maximum rec-
ommended amplifier power for that
specific loudspeaker model.  Please
see the specification section for
details.  Following these guidelines
will provide virtually distortion-free
sound reproduction and long loud-
speaker life.

The vast majority of new speaker
“malfunctions” end up being traced to
connections or switch settings. To
avoid packing up correctly functioning
speakers and sending them off, only
to find that they’re not really at fault,
check the following tips first, before
requesting service.

No sound at all or very faint sound
from both speakers
1

. Amp/receiver tape monitor button

pushed in while using CD, FM or
phono inputs.

Wrong speaker switch, “A” or  “B”

speaker output.

. Sound source (CD, cassette deck,

turntable) not turned on, not activated,
not hooked up or not selected on
amp/receiver front panel.

No sound from one speaker
1. 

Balance control turned all the way

left or right.

Speaker wire has become discon-

nected.

. One of the connections between

sound source and amp/receiver is
faulty or has become disconnected.

Both speakers play at low volumes 
but shut off as volume is in-
creased OR sound turns on and 
off intermittently

A few strands of speaker wire may 
be shorting out. Recheck the con-
nections. Recheck the impedance of
the amp.

Bass is very weak AND/OR sound
seems to come from each speaker
separately, without creating a 
stable stereo image between the
speakers.

The polarity (+ & –) of one speaker

has been reversed relative to the
other. Double check connections.

Speakers are too far away from

back and side walls or too far apart.
Experiment again with the speaker
placement. If you are still encounter-
ing problems, consult your JBL
dealer.

J Series OM  7/28/98 10:20 AM  Page 5