Adjusting Equalizer Controls
KQ30 Equalizer Technical Manual
Version 1.0
January 1, 2002 Page 17
With the SPL set an the pink noise continuously playing through your system, put the RTA into analyzer mode.
You will now see a graphical representation of how your system is working at playing back the pink noise test sig-
nal. Figure 1 gives you an idea of what
you should be seeing, except yours will
be moving up and down at the various
frequencies.
The pink noise that you are playing
through your system is a recording of
equal energy at all octaves being played
at the same time. If you were to look at
it as a pure signal, before it went
through all your amplifiers, crossovers
and speakers, it would like the display in
Figure 2.
How is this useful? Well knowing that
the signal coming off the CD before it
goes through your system is supposed
to look like a flat line gives you a known
reference. Looking at it with a micro-
phone after it has gone through your
head unit, equalizers, crossovers, ampli-
fiers, and finally your speakers gives you
an idea of how the signal is being affect-
ed by these components.
You also see the effect that speaker
placement and phasing has on what you
hear as well as how the car itself is
affecting the signal.
The end result is the ability to look at how everything, and we mean everything, is affecting the sound you hear
in your car. Does this mean we should equalize the car back to a flat line? The short answer is no. The long answer
is no, unless you just want a flat line for showing you can do it. Many competitors will shoot for the flat line so they
can get a “perfect score” in the RTA judging section of a contest but for listening a flat line would sound fairly dull
and lifeless. That is why they use separate EQ’s and switch between them. One for the RTA judging set up to get as
close to a flat line as possible and the other for sound quality. If you don’t believe me, just check with my cousin
Bernie...you know the one...claims he can hear grass grow. I told you about him right?
So if I am playing a source which is essentially a flat line and you don’t want me to equalize it back to a flat line,
just what am I supposed to do? The key to using the RTA and pink noise is to look for major problems with the
response curve and smooth them out. Remember from the introduction that we said 3 dB changes between 1/3
octave bands was the smallest change the human ear can detect? Well that is what we are trying to do here, sim-
ply keep each 1/3 octave band within 3 dB of the other as we go from 20 Hz to 20 kHz.
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20 40 63 100 156 250 400 635 1K 1.6K 2.5K 4K 6.4K 10K 16K
31.5 50 80 126 200 320 500 800 1.27K 2K 3.2K 5K 8K 12.8K 20K
Audio Leap RTA Unit
Real Time Spectrum Analyzer
Beer/Whiskey
Dot/Bar
Fast/Slow
Average
Freeze
Fig. 1
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+1
0
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20 40 63 100 156 250 400 635 1K 1.6K 2.5K 4K 6.4K 10K 16K
31.5 50 80 126 200 320 500 800 1.27K 2K 3.2K 5K 8K 12.8K 20K
Audio Leap RTA Unit
Real Time Spectrum Analyzer
Beer/Whiskey
Dot/Bar
Fast/Slow
Average
Freeze
Fig. 2
