Sonnox Oxford Limiter - Manual (Page 23)

9.3 Noise
Shaping
Depth
Control 9 DITHER AND NOISE SHAPING
The Oxford Limiter includes four noise-shaping curves: Types 1 and 3 are fifth order and
Types 2 and 4 are third order designs, representing a varied set of trade-offs to suit most
programme types, as illustrated below:
Whilst it is understood that the selection of noise shaping type is largely a matter of user
preference, generally speaking Types 1 and 2 produce the most dramatic reduction in
overall noise loudness, with Type 1 being the most effective of all. Types 3 and 4 provide
gentler responses, which under some circumstances may produce less intrusive sounding
spectrums, at the expense of higher audible residual noise. Type 3 also provides greater
noise attenuation in the range between 10KHz and 16KHz, at the expense of higher noise
levels in the mid ranges.
9.3 Noise
Shaping
Depth
Control
From the previous section it can be seen that noise shaping can potentially cause
unwanted effects in equipment and processes down line, particularly if the programme is
to be further modified, such as in mastering situations. Some unwanted effects may
include:
• Marked increase in noise levels if the file is not transferred intact bit for bit, (ie. if
further processing is implemented)
• Premature meter readings in silence
• Premature peak level overloads (as increased dither levels add to peak signal value)
• Unwanted low-level behaviour in dynamics processing
• Disturbance caused to data reduction encoding processes such as MP3, WMA etc.
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