page 3 – 48
AM-10HD / Aug 2008
A M - 1 0 H D G U I
Delayed Release
Controls the secondary (slow) release of the lookahead limiter, and is adjust‑
able from 100 milliseconds to 1 second.
When Delayed Release is engaged via the Delayed Release checkbox, the
limiter will release the first 3dB of gain reduction at the (faster) Release setting,
and the remainder of the Release at the Delayed Release timing. This permits a
drastic reduction in intermodulation distortion and allows more limiting depth
without incurring the usual distortion penalty.
Clip Style (Main Clipper)
Three final clipper styles are offered in the Main Clipper to en
‑
able the end user to create the on‑air sound desired. All settings offer
excellent peak control because the main clipper is followed by a non‑
clipping overshoot calculator that removes peaks that, due to their
frequency and energy content, would cause the main 15kHz lowpass
filter to ring or overshoot.
The Main Clipper drive level is determined primarily by the setting
of the Lim/Clip (Limiter/Clipper) Drive control as well as the amount
of activity occurring in the 10‑band section.
Off – Defeats all clipping in the main AM limiter, noting that the
overshoot calculator is always active and may act like a non‑band
limited/non‑distortion cancelled “clipper” when overdriven with
test tones or program material.
Hard
– The Hard clipper style has an infinite ratio with no increase in peak
levels once its threshold is achieved. This clipper adds brightness and density
to the program.
This clip style is the “cleanest” of the three styles because, unlike the other two
(see below), no clipping occurs below the clip threshold. The other reason this
is a “cleaner” clipper is because the distortion spectrum created by this style
is more easily manipulated by the distortion cancellation scheme.
The Hard style creates predominately harmonic distortion up to approximately
0.5dB of drive, depending on the incoming program material.
Firm – The Firm clipper style has a transfer function that allows progressively
higher ratios over approximately a 0.5dB transition region. It is a softer sound‑
ing clipper than the Hard style and is also more forgiving in drive level, but
can sound grainy on some material because the distortion spectrum is richer
and not as easily managed by the distortion cancellation scheme.
The Firm style creates both harmonic and intermodulation distortion, with the
balance leaning towards harmonic rather than intermodulation.
Round – The Round style has a transfer function that allows progressively
higher ratios over approximately a 1.05dB transition region. This is the most
forgiving of the three clipper styles as far as drive levels are concerned and
contributes “roundness” to the audio without sounding overly harsh. However,
it is the least “distortion cancelled” of the three styles simply because of the
richer harmonic spectrum created by its action.
