Page 3Page 2 TRIDENT 80B EQ 500 User Guide
Begin with all boost/cut controls - those with centre detents, set to their mid way
('0') positions. Adjust the low and high mid frequency sweep controls to their
minimum positions (fully anticlockwise). The 50Hz high pass 'Filter' button should
be in the out position. Set the frequency select buttons controlling the high and
low shelving sections, to 120Hz and 12kHz respectively. Lastly, set the 'EQ' button
to the 'in' position (the associated LED will illuminate).
Rotation of the high frequency shelving control in a clockwise direction emphasises
high frequencies, while turning the control in an anti-clockwise direction
from centre attenuates high frequencies.
Operating the 'frequency select' button in the high frequency section introduces a
subtle change of emphasis to the affected high frequencies, as the shelving
'knee' is changed from 12kHz to 8kHz. Likewise, rotating the low frequency
shelving control in a clockwise direction will emphasise low frequencies, while
turning the control in an anti-clockwise direction from centre attenuates low
frequencies. Adjusting the 'frequency select' button in the low section introduces
a subtle change of emphasis on the affected low frequencies by altering the
shelving point from 120Hz down to 60Hz.
The 'low mid' and 'high mid' equaliser sections are peaking filters. Adjustment of
their parameters is achieved by use of the boost/cut knob and its associated
frequency sweep knob. Boost or cut of a given frequency is performed by moving
that control from its centre detent position: clockwise for boost, anti-clockwise to
cut. The frequency to be boosted or cut is selected by the frequency sweep
control knob. The range of frequencies of the 'low mid' control extends from
100Hz up to 1.5kHz.
For the 'high mid' sweep, the frequency range begins at 1kHz (overlapping with
the low mid section) and continues up to 15kHz.
The Series 80B 500 Series EQ incorporates a classic four band equaliser which is
identical to that employed in the Trident Series 80 console. It consists of frequency
switchable high and low pass shelving sections, coupled with two swept low and
high mid range bands and a switchable 50Hz, 12dB per octave filter. Both swept
midranges have been carefully chosen for maximum effect on music programme
and a good degree of overlap is provided.
Finally, selecting the 'Filter' button introduces a smooth, 50Hz, 12dB/octave
roll-off to effectively eliminate 'rumble' caused by, among other things, someone's
feet moving about near a microphone stand, nearby traffic noise and AC systems.
The amount of boost (accentuation) or cut (attenuation) that is applied to the
audio signal is entirely dependent on the programme content and it is not our
intention to advise on this. Application of equalisation is a very subjective matter
and is best learned by experiment. The equaliser bypass button 'EQ' is a useful
facility for comparing the signal before and after the application of equalization.
For those not familiar with the difference
between a shelving and peaking equaliser,
the differences are as follows. A shelving
equaliser boosts (or attenuates) all
frequencies equally, above or below a
certain point. The frequency specified for a
shelving equaliser circuit is usually at the
point where it effectively reaches its 'shelf'
state. A 'high shelf' EQ boosts/cuts high
frequencies and a 'low shelf' type
boosts/cuts low frequencies. This type of
circuit is very popular in hi-fi systems but is
also actually highly musical, when applied
in a recording environment. In contrast, a
peaking equaliser is one that, as its name
implies, has a centre frequency that is
boosted or attenuated more than others.
The frequency range over which it reaches
its peak and then falls down is known as
the bandwidth (or 'Q'). Because this type of
design reaches a peak and then falls away,
it is possible with this type of circuit to
'home in' on particular frequencies and
make adjustments without affecting those
around them. This can be particularly
useful when working with instruments
such as bass guitars and snare drums. By
incorporating both shelving and peaking
equalisers into the design of the 80B, it is
possible to get the best of both types of
design.
THE EQUALISER
TRIDENT 80B EQ 500 User Guide
OPERATING THE EQUALISER
