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AM-10HD / Aug 2008
A M - 1 0 H D G U I
Input Levels / Gain Reduction Meter (Left of Graph)
The vertical bargraph meters to the left of the graphical display show input levels and
gain reduction, respectively, with the right meter pair switchable to display the gain reduc‑
tion for the HD Lookahead Limiter, AM Lookahead Limiter (and clipper), or the AGC and
Compressor. When the meter is in the “Context” position its mode changes as the different
processing screens are navigated showing the processing’s gain reduction activity in the
currently displayed screen.
Output Meter (Right of Graph)
The vertical bargraph meters to the right of the graphical display show the output
levels of the processor. The rightmost meter always displays the output levels for the HD
processing chain. The left meter pair can be switched to display the Analog or AES output
levels of the analog side of the processing chain.
60dB Range
To the left of the Input meter screen is a check box labeled “60 dB Range;” when
checked, it toggles the Input meter from the normal 30dB view range to a 60dB range. The
latter range is useful for “finding” signals during initial set‑up, or for observing program
material when the signal source is of high dynamic range, such as live classical music.
Display Signal Selection
Beneath the graph area are two large buttons: Input and PreDelay.
By single clicking on a button a green indicator on the button will light to indicate
which signal is being viewed on the large graphical display above it.
Input
Pressing this button enables a Fast‑Fourier Transform (FFT) based real‑time spectral
analysis of the selected (Left/Right) input signal – this occurs if the leftmost “Audio”
checkbox is checked and the rightmost “O‑Scope” checkbox is not checked. An FFT is a
mathematical filtering process which calculates the spectral content of a time domain signal.
The FFT
1
is widely used in test equipment in the audio industry because of its extremely
precise measurement capability. Thanks to the extremely efficient DSP chips utilized in
the AM‑10HD, we are able to offer the same exotic measurement capability in an audio
processor. Thus what you see on our graphics displays is as precise as current technology
permits.
1
The Fourier analysis is named after French mathematician and physicist Jean Baptiste Joseph Fourier,
who first explained it. For more information on the FFT and some of its capabilities, please consult the
“Handbook for Sound Engineers” by Glen Ballou and published by the Howard W. Sams Company (ISBN
0‑672‑21983‑2).
PreDelay
Pressing this button enables the viewing of the output of the AM processing chain prior
to the diversity delay.
