Chapter 7: Using The Compressor
Manual mode with hard knee (linear peak)
With the HARD pushbutton switched on, the compressor is peak sensing with manually
adjustable linear attack and second order release envelope characteristics. For limiter
applications, a high ratio combined with fast
attack times are best; set the release slow to minimise distortion on low frequency instruments. Lower ratios with slow attack and relatively fast release provide transparent
compression with some dynamic control, which does not unduly affect the intentional dynamic
content of the source material. This can be used with difficult instruments like acoustic guitar to keep equal perceived loudness within a mix, without producing excessive flutter or distortion.
Auto mode with hard knee (exponential RMS)
With both the AUTO and HARD pushbuttons
switched on, the compressor is RMS sensing using exponential attack and release. The RMS averaging process defines the attack and release times to produce a very adaptive envelope character. This provides faster attacks on large
(over threshold) signal changes and produces slower attacks on small signal changes. The lack of manual time constant settings makes this
mode very fast and simple to set up on most programme material. It is also sonically
accurate and works well for limiting of vocals and compression of many other sources.
Auto mode with soft knee (exponential RMS)
With the AUTO pushbutton switched on, the compressor is RMS sensing with an underlying exponential attack and release characteristic that is slightly modified by the soft knee curvature. This produces extremely natural results, even with higher compression ratios, and is especially suited for vocals.
Limiter
A limiter is essentially an extreme form of compressor that only affects signals above a selected threshold level (dB). This is particularly useful for limiting only peaks in the signal, while leaving the rest of the signal alone. A limiter acts as a last check on signal level. If the level goes over threshold, fast acting, high ratio compression is applied to bring it back within bounds.
To set up the DN540 as a limiter, select the compressor to operate in manual and hard knee mode (see “Manual mode with hard knee (linear peak)” on page 24) with attack
set to fastest (20ms) and the ratio set to infinity to one (4:1). Adjust release to suit the programme and set threshold as required.
| DN540 |
24 | Operator Manual |