Trident Series 80B Owners Manual5
Trident Series 80B Description
Equalizer
The Series 80B® rack 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 eect on music programme and a good degree of overlap is provided.
For those not familiar with the dierence between a shelving and peaking equaliser, the dierences 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 eectively 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 con-
trast, 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 aecting 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 Series 80B®, it is possible to get the best of both types of design.
Operating the Equalizer
Set the input level in accordance with the procedures detailed in the ‘Input Section’ section of this manual. 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’ switch
should be in the out position. Set the frequency select switches controlling the high and low shelving sections, to
120Hz and 12kHz respectively. Lastly, set the ‘EQ’ switch 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’
switch in the high frequency section introduces a subtle change of emphasis to the aected 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’ switch in the low section introduces a subtle change of emphasis
on the aected low frequencies by altering the shelving point from 120Hzdown to 60Hz.
The ‘low mid’ and ‘high mid’ equaliser sections are peaking filters. Adjustment of their parameters is achieved by
use of the (center-detented) boost/cut knob and its associated frequency sweep knob. (The relation between
each pair of controls is denoted by a white line on the front panel connecting the two together). 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.
Finally, selecting the ‘Filter’ switch introduces a smooth, 50Hz, 12dB/octave roll-o to eectively eliminate ‘rumble’
caused by, among other things, someone’s feet moving about near a microphone stand, nearby trac 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 sub-
jective matter and is best learned by experiment. The equaliser bypass switch ‘EQ’ is a useful facility for comparing
the signal before and after the application of equalisation.
