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Application Notes
DN540
30 Operator Manual
compressor relaxes there is no gain reduction — but the upper frequency boost
remains, increasing noise and making microphonic feedback much more likely.
The DN540’s presence accentuation corrects the tendency for dull sound during
compression, without changing the sound of uncompressed signals. It reduces the ratio
of the compressor in a relatively broad range of frequencies centred on 5kHz, and the
effect is continuously variable, so as much presence accentuation can be added as
needed or to suit taste.
When presence accentuation is applied, any compression acts on the high frequencies
to a lesser extent than the low frequencies, by an amount set by the user. The
transient at start of a sound is greatly reduced in the low frequency content, which is
where all the power that needs to be controlled lies, but the harmonic content is
preserved in a more natural and dynamic state.
The presence band has been specifically located in an area where we are most
perceptive to sounds, so that reducing compression ratios in this area allows much
greater compression to be applied at the other frequencies without sounding unnatural.
Presence accentuating compression can produce results that are very similar to
multi-band compression, but with only one additional control required (as opposed to
many) it is much more straightforward to set up and uses far less rack space.
Some additional corrective benefits from presence accentuation are:
• Reduction of source inter-modulation It is very common for pop/rock singers
to stand in front of drum kits, and unless suitable screens are placed between them
there will be a lot of spill from the kit. Often you can hear the compressor on the
vocalist modulating the spill from cymbals, which sounds very unnatural. This can
be eliminated by using the presence accentuation to stabilise the higher frequencies,
and if that makes the vocals sound too bright the high frequencies can be reduced a
little using EQ, thus reducing the spill and reducing the chances of high frequency
howl-round.
• Reduction of breathing Most processing noise occurs in the presence band and it
is much more noticeable when it is modulated by the compression of a sound source.
Similarly for the reduction of source inter-modulation, presence masking can
eliminate this effect.
• Reduction of pumping Because human hearing is so sensitive to presence band
frequencies, stabilising their dynamic response with presence accentuation can mask
the pumping effects at lower frequencies.
• Reduction of dull sound and increased brilliance It is often tempting to boost
high frequencies to get sounds to cut through a mix, but in sound reinforcement this
increases the likelihood of howl-round. Presence accentuation can help to increase
the brilliance of compressed sounds by correcting their tendency to sound dull, and
with increased use it can be used creatively to add even more high frequency energy
without increasing the risk of howl-round.
Thus, the presence accentuation feature of the DN540 adds another tool for the sound
engineer that can be used to enhance and compliment the application of many types of
compression.