User guide

PreMax™ Preamp and EQ
True to the Music
®
Radial Engineering Ltd.
6
USING THE EQUALIZER
Once you have the preamplifi er working, activate the equalizer
using the EQ-IN switch and begin testing the three EQ bands.
Each of the three bands uses an active EQ control capable of
cutting, or boosting the amplitude within the band’s frequency
range. The center, 12 o’clock position, is the neutral point or
0dB. Rotating the control clockwise from center will boost
frequencies. Turning it counter clockwise from center cuts them.
Start your experimentation with the high and low shelving
fi lters set at the 12 o’clock position. These fi lters affect the
treble and bass frequencies and offer 12dB of cut or boost.
These ‘shelving’ fi lters gradually increase amplitude from a
fi xed frequency to the limit of the audio spectrum.
Low frequency EQ Mid-range frequency EQ High frequency EQ
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The mid-range is a constant-Q fi lter that forms a bell-shaped curve centered around the
middle of the audio spectrum. As the amount of boost or cut is increased, a wider band of
frequencies are affected and the mid-range begins to overlap and interact with the high and
low bands.
You can take advantage of the interaction between bands to produce an EQ curve that a
single fi lter can not achieve on it’s own. For instance, boosting the mid-range while cutting
high band can produce a complex frequency response that accentuates the high-mids but
rolls-off the hiss. Likewise, cutting the bass and boosting the mids will accentuate low-mid
frequencies while also cutting out low frequency rumble. Taking this further, you can employ
the high-pass fi lter in the preamp section to cut deep bass.
The mid-range is superimposed over the high and
low fi lters to show the frequency overlap between bands.
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BOOSTCUT