Manual-4
Dynamic EQ Applications
Auto-Correct Microphone Proximity Effect
Use Dynamic EQ to automatically correct for timbre changes
due to the low frequency boost caused by the proximity effect
of cardioid microphones (see Figure 6), which occurs when a
singer/speaker does not remain a consistent distance from the
microphone.
Two opposite applications share this problem:
1. The first occurs when the mic is located far enough from the
person that the proximity effect has no bearing (typically
a podium situation), then the speaker leans in closer to the
microphone causing a low frequency boost.
Start with a 100 – 250 Hz center frequency, a bandwidth of 2
octaves and a ratio of 3:1. Set the threshold high enough so when
the person is the normal distance there is no response, and only
when they move closer to the mic does the threshold kick the
filter into action.
2. The second application compensates for the loss of proximity
effect as the person moves the microphone away from their
mouth; typical of most hand held mics.
Solve this problem by perform the opposite routine as the po-
dium mic example above. Have the person hold the microphone
at the farthest distance from their mouth that can occur. Set the
Dynamic EQ so that it is just below threshold. Once they move
the mic closer to their mouth it will reduce the low frequency
boost. Since we have become accustomed to hearing the proxim-
ity effect try low ratios so that the tonality change is slight, but
remains more consistent than without the Dynamic EQ. Use
appropriate EQ on the input channel to add back in any missing
warmth – this warms the signal while the Dynamic EQ keeps
the tonality consistent.
Typical starting points are a frequency of 100 – 250 Hz, a band-
width of 2.0 octaves and a ratio of 2:1 depending on the desired
change in tonality.
Auto-EQ Changing Sound Sources
A great example is evening out the tone, or timbre, of a guitar
amplifier. Using two channels set up for different tones is very
common to switch between a rhythm tone and a lead tone. Of-
ten the musician sets the lead tone brighter than the rhythm tone
so it cuts through better. The problem comes when the sound
system amplifies this all out of proportion, resulting in too much
energy around 2 kHz – 4 kHz (a really nasty frequency range
due to the ear’s maximum sensitivity to this octave).
Setting the Dynamic EQ for a center frequency of 3 kHz and
a bandwidth of about 1 octave cleans this up. Set the threshold
high enough so that during normal playing nothing is happen-
ing. If the device uses relative threshold, once the lead channel
is used it will automatically see the change in timbre and apply
the Dynamic EQ to reduce the excess energy at 3 kHz relative to
the rest of the audio spectrum. You can also use this technique
to make guitar sounds “thick” and “chunky” without being over-
bearing by using the EQ section set in the 200 Hz range as well.
Improve Vocals
It is common for female singers to have a wide tonality swing
when shifting from a quiet breathy passage to a loud crescendo.
The voice sounds warm and pleasant during the quiet passage
but shows a predominance of frequencies in the 1.2 kHz range
for the loud crescendo. This is exaggerated when the singer
moves the microphone away from her mouth thereby removing
the warming character of the microphone’s proximity effect and
adds to the naturally occurring peak in this frequency range.
To fix this, simply set the EQ section to the problem frequency
(typically 1.2 kHz) and set the threshold so that the compres-
sor only kicks in when she sings the loud passages. Use the ratio
control to determine exactly how much of the original tone
change remains – low ratios leave more change while high ratios
clamp down hard and allow very little change.
Create Radical Sounds
Dynamic EQ lets the user create sounds that change tone with
level, or at extreme settings, which allows the creation of radical
sounds based on the threshold, attack & release times.
Experiment – the results will amaze you.
Figure 6. Microphone Proximity Effect
(courtesy of Shure Inc.) Low
frequencies rise as the sound source gets closer to a cardioid microphone.
