Eminent Technology's Multimedia Speaker Test
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These test are provided to help you make sure that your multimedia
speakers are set up and performing correctly. Information is provided
about each tone to help you understand what it should do. We suggest
that you read these notes.
First we have to provide you with the usual warnings about damage
to your multimedia speaker. A few of the test tones provided here
could be inaudible but damage your multimedia speakers IF you
turn the volume control up. However for all of the test included
here, no damage will result if you leave the volume control at
its normal listening position. (Owners of the Eminent Technology
LFT-11 do not have to worry about damage)
250 Hz Sine wave test tone - This test tone is a sine wave which
has no harmonic content. It should sound like it comes from the
center of the monitor if you balance control is set correctly.
The frequency or pitch is close to middle "C" on the
piano, actually a little flat, and it should sound clean. If
you hear buzzing or other sounds besides a single tone make sure
that your mixer and all volume controls are set correctly.
500 Hz Left Sine wave test tone - This test tone is one octave
higher or twice as high as the above test. Again it should sound
clean and pure with absolutely no distortion or buzzing. It should
only appear to come from the LEFT speaker and nothing should come
from the right speaker. IF the sound comes from the right speaker
then your speakers are attached incorrectly and the cables should
be moved at you amplifier. Move the wire from the left speaker
to the opposite speaker output plug or connector on your amplifier
and move the wire from the right speaker to the remaining plug
on your amplifier.
500 Hz Right Sine wave test tone - As above, this test tone should
appear to come from the Right speaker and nothing should come
from the left speaker.
Pink Noise Monaural - Pink noise is a form of noise that theoretically
contains all frequencies. It should sound somewhat like rain on
a rooftop. Pink noise is defined as having equal energy per octave
and it is an important signal for loudspeaker testing if you have
speaker measurement equipment. In this example, if your speakers
are in phase, the sound should appear to come from the middle
of the monitor.
Pink Noise with Reversed Polarity - This is the same sound as above, but
recorded with its polarity reversed. Here the sound should appear to come from
the left and right speakers individually, or beyond the outside
boundaries of the speakers. If it sounds like this noise is coming
from the center of your monitor then your speakers are wired incorrectly. To correct this problem you will need to switch the
positive and negative wires at there terminals on ONE speaker
only and it would not matter which one you change.
30 Hz Tone - This is a very low frequency tone. The majority of
multimedia speakers will not play this frequency. Although this
is not the lowest frequency found in music or multimedia it is
a stringent test for a multimedia woofer. If you turn up the volume
on this test , you might hear distortion before you hear the test
signal. If your multimedia speaker can play this then you are
in the big leagues.
50 Hz Tone - This is also a very low frequency test tone. If
your system will not play the 30 Hz tone above it might reproduce this tone that is a little higher
in frequency. The same rules apply as above. A good multimedia system should reproduce this signal
cleanly and without any distortion or buzzing. This tone is also a little easier for the human ear
to detect and recognize as sound.
100 Hz Tone - This tone can serve two purposes. First if your
multimedia speaker has very limited low frequency response and it failed to play the lower frequency test
tones above, then try this one. Second, if you are using more than one multimedia system in a surround sound
application, or a subwoofer with a multimedia system, then you want both systems to be in phase with each other.
You want all of the speakers to move in the same direction at the same time. If you switch the phase
of one speaker system while playing this tone, the loudness of the tone will change. When the two systems
are out of phase, you will hear much less sound output at this frequency and when the two systems
are in phase this tone will be loud. (Changing the phase means reversing the wires of one set of speakers,
left and right, relative to the other. You can do this at the amplifier output terminals, or at the
speaker input terminals by connecting the positive wire of the amplifier to the negative wire of the
speaker teminal along with the negative wires at each into the remaining positive terminals.
DO NOT do this with the amplifier turned on as it could be damaged.)
1000 Hz test Tone - This test frequency is also a sine wave. For
testing purposes sine waves are used because they are difficult
to reproduce accurately and any audible harmonics are a form of
distortion in your playback system. This frequency is sometimes
used as an test tone for radio stations or TV stations.
10,000 Hz test Tone - again this is a sine wave but at a very
high frequency. Subjectively, this is difficult to describe because
it is a very high pitch and you will probably barely be able to
hear it even if your ears are good. Most multimedia speakers will
play this tone. This is generally not perceived as a musical note.
15,000 Hz test Tone - Also a sine wave but at such a high frequency
that many adults might not be able to hear it and many multimedia
speakers might not play at a loud enough level to be audible.
Our ears are naturally insensitive to frequencies this high. We
do not recommend turning up the volume on this one. If you have
a multimedia speaker with a tweeter then damage could result if
the speaker is turned up loud for even a short period of time.
Thats it. If your multimedia speaker played all of these
tones and did so correctly then you not only have a good multimedia
speaker, but have good hearing as well.
Here are some links to pages with 3D sound effects that can be reproduced with two channel sound systems. The Eminent Technology LFT-11 excels at reproducing these sound effects because of the directional characteristics of the flat panel transducer.
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