Dynamic Equaliser (D-Eq) - Solid State Logic THE BUS+ User Manual

Tutorial

Dynamic Equaliser (D-EQ)

Many engineers use regular ('static') EQ in addition to their master bus compression, often feeling that they need to compensate
for the psychoacoustic perception of 'dulling' that compression can bring. Also, in general, many engineers apply a static EQ
across their mix as part of their mixing template to help achieve the level of bass and presence that modern productions require.
A Dynamic EQ, however, is a more 'intelligent' form of EQ which changes the gain of an EQ band proportionally in response to
the signal level once above a set threshold. Dynamic EQs allow you to modify the contrast between background material (under
threshold) and forward material (above threshold). Whilst putting together the concept for The Bus+, we wanted to build in a
Dynamic EQ that could be applied either before or after compression. After a considerable amount of research and development,
we came up with a design for the first-ever SSL Dynamic EQ - the D-EQ. The side-chain is a specially adapted version of the Bus
Compressor side-chain with additional circuitry such as the gain reduction limiter for the Range parameter. We think the D-EQ is
every bit as musical and powerful as the Bus Compressor itself. Some people may think of dynamic EQ as a tool fulfilling a similar
role to that of a multi-band compressor (without the cross-over phasing issues caused by band-splits of a multi-band design),
which is definitely one way of looking at it. However, through exploring the power of the D-EQ, we are certain you will find many
more creative uses beyond this, particularly using the expansion to enhance source material.
D-EQ CONTROLS
The D-EQ is a 2-band (LF and HF) dynamic EQ, with both engines able
to be turned on/off (bypassed) individually. The default frequency of
the LF Shelf is 60 Hz. The default frequency of the HF Shelf is 6 kHz.
When the HF Shelf is changed to a Bell (using the HF BELL switch),
the default frequency is 4 kHz. All of these frequency points can be
adjusted - see the D-EQ Frequency & Range Selection section.
BAND ON/OFF
To turn an engine on/off, simply press the LF (low frequency) or HF (high
frequency) control. It's easy to tell if the band is on as the corresponding
A push on the control will toggle the band on/off.
D-EQ switches (LF FAST / HF FAST & HF BELL) will become backlit.
COMP/EXP
Each band has a 31-position stepped control labelled with COMP and
EXP at the extremes of the control. As you turn the control clockwise
from the centre position '0' (no effect), you start dialling in an
expansion effect. Moving the control anti-clockwise, you start dialling
in a compression effect. By turning the control in either scenario, you
are effectively lowering the Threshold of the D-EQ, therefore how far
you need to turn it before either expansion or compression happens
will be dependent on the signal level.
D-EQ Activity LEDs
Above the LF and HF D-EQ controls are tri-colour LEDs, indicating
'how much' dynamic EQ is being added/subtracted by fading
Think of the activity LEDs as being the equivalent
between off, green, orange and red colours. The green LED starts to
feedback you get from the meter for the Bus
come on with 0.5 dB of activity, reaching full green colour with 5dB.
Compressor.
Full orange is recognising 10 dB of activity, whilst full red indicates 15
dB of processing is occurring.
THE BUS+ User Guide
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