"Noise", as used in this document, is a general term referring to
any sound a speaker system makes that is not part of the original
source material. There are many different types and sources of noise,
each with its own solution. Below is an explanation of the common types
of noise, what causes them, and how to minimize their occurrence.
Hum or Buzz
There are four common causes of humming and buzzing:
Pops and Clicks
- Sound card If the humming or buzzing gets louder or softer
with changes in the volume setting, this is an indication of noise
coming from the sound card. In this case, check all of the connections
to the sound card to make sure they are all completely plugged in and
secure. Then, adjust the level setting of the sound mixer to obtain the
best performance. Generally, you should leave your CD volume settings
in the mixer at full and reduce the sound card's master output level
down. For information on doing this, please refer to your sound card
- Unused input cables If you are not using all of the source
inputs to your speaker system (such as using a 5.1 speaker system with
a 4 channel sound card), the unused input cables will pick up noise.
The solution is different for each speaker system, as described below:
Z-540 / Z-560 (2 channel sound card): Depress the M3D button.
Z-640 (4 channel sound card): Depress the Matrix button.
Z-680 (2 or 4 channel sound card): Disconnect the unused input cables from the control pod
- High-power devices If you are using other high powered
devices on the same electrical circuit, they may be causing hum or
buzz. If so, discontinue their use while you are using your speaker
system. Examples of such devices include microwave ovens, halogen
lamps, power tools, etc.
Also note that high-power devices with dimmer switches (such as
halogen torchiere lamps) will cause an especially pronounced buzzing
effect. To minimize hum or buzz, make sure that the dimmer switch on
these products is either all the way on or off.
- Electric Polarity In many countries, the US being one, the
electrical power grid is polarized. In these countries, the power plugs
are designed so they can only be inserted into the wall socket in a
single direction. For example, in the US one of the plug blades is
larger than the other. To avoid humming and buzzing, both your computer
and speaker system must be properly plugged into polarized outlets. If
your wall outlets do not have polarized plugs, as in the case of many
older homes, and you are using adapters to plug these power cords into
the wall, it is possible that the polarity of either your computer or
your speaker system is reversed. In many other countries, such as most
of the European continent, wall sockets are not polarized at all -
making it even more difficult to properly match the computer and
To solve the problem you will need to remove the power plug from
the wall outlet, rotate the plug 180°, and re-insert it into the wall.
Try this for your speaker system power cord, your computer power cord,
or both. You should be able to find a combination that will eliminate
the humming and buzzing.
There are three main causes of pops and clicks:
- Sound Card Many pops and clicks are created by the sound
card. There are two common causes: sound card quality and older or
mismatched drivers. If the overall volume level of the pops and clicks
goes up and down as you change the volume on the speaker system, the
noise is being generated by your sound card. Lower quality sound cards
don't include the necessary circuitry to cleanly remove noise from the
sound output. Logitech's higher-powered systems, such as the Z-560 and
Z-680, are also sensitive to the overall quality level of the sound
card. If you are using an older or lower quality sound card, we suggest
upgrading your sound card.
The other primary cause is older or mismatched drivers. Make sure you are using the latest drivers for your sound card.
- Multi-tasking If you are running more than one program on
your computer that accesses the sound system at the same time, small
pops and clicks can be common. This is a function of your computer
and/or sound card. A common example is using a program that generates
occasional audio feedback (such as beeps or other sound effects) while
listening to an MP3 track in the background. The solution is to turn
off audio feedback in the first application so that the background MP3
track is uninterrupted.
- Interrupts in the Digital Bitstream On digital systems,
such as the Z-680, it is normal to hear a very faint "tick" when you
switch between inputs (by pressing the input button). You may also hear
louder 'clicks' or 'pops' on a device such as a standalone DVD player
or a sound card if it is plugged into one of the digital inputs. On
some systems, this noise may occur when skipping tracks, switching
audio streams (for example, from Dolby Digital to DTS), or navigating a
DVD menu. The clicks and pops occur because the device is sending out
an interrupted digital data stream. This behavior generally occurs with
older software and older players, but is uncommon on most modern
The Z-680 has been extensively tested with the latest sound cards,
software DVD players, and standalone DVD and CD players. If you
experience extensive popping and clicking, we suggest upgrading to the
latest version of your software DVD player or, if using a stand alone
device, trying a different speaker model. If you need more assistance
with this issue, please contact Customer Support.
A stuttering sound track is an indication of either insufficient or
conflicting computer resources. Check to make sure that your computer
has sufficient processor power and memory to handle the applications
you are running, especially if you are using a software DVD player.
Defragmenting your hard drive may also help. If you are sure you have
sufficient resources, check to make sure that you don't have any
conflicting IRQ or DMA channels.
We have also seen some software DVD player/sound card combinations
that cannot properly output a Dolby Digital or DTS signal through the
sound card's S/PDIF digital connector. (S/PDIF is a generic term for
either coax or optical digital connections.) The result, when using a
Z-680 hooked up to a S/PDIF connector, is a stuttering soundtrack. As
mentioned, this stuttering is caused by the computer, not the Z-680
speakers. Switching the software DVD player's sound output to the 5.1
analog outputs will generally solve this problem.
All high-powered amplification devices - everything from multimedia
systems to home theater systems to movie theater sound systems --
generate some level of background noise, or hiss. In addition, low
quality sound cards with poor signal-to-noise ratios can generate a
significant amount of steady hiss that is reproduced on the speakers.
Under normal conditions at a normal listening distance, the hiss coming
from the sound system should not be noticeable. In a very quiet room,
or if you place your ear very close to the speaker, you may hear a very
low level hiss. This is normal, but should be completely masked by
normal music and game sounds.
If you find that hiss is noticeable, it is likely that the speakers
are too close to your listening position. If the speakers are too
close, you will not obtain the best imaging of the sound and you risk
damage to your hearing when the system is playing at full power levels.
Try moving the speakers further away from your normal listening
position. We recommend at least 18" for the moderately-powered systems
(such as Z-340, Z-540, and Z-640) and at least 30" for higher-powered
systems (such as the Z-560 and Z-680).
Also, note that the satellites in most Logitech speaker products are
designed to be wall-mounted. Wall mounting the speakers provides two
benefits: 1) it moves the of the satellites further away from your
listening position, making any hiss less noticeable and 2) it moves all
of the satellites further away from each other, providing better
channel separation and surround sound spatialization.