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AM-10HD / Aug 2008
G E N E R A L I N F O R M A T I O N
Overview
At the heart of the AM-10HD is a specialized DSP farm containing both floating
and fixed-point processors. Advanced signal routing capability allows restructuring the
processing chain as desired, and headphone monitoring can be patched to any processing
section at will. The flexibility of the headphone monitoring also allows an audio source
that is attached to the AM-10HD but not even on the air to be monitored!
The most salient feature of the AM-10HD is its specialized “tuned for AM”10-band
final processing section. This 10-band final processor morphs its operation as the AM
bandwidth is changed, ensuring that there are always 10 bands of limiting available
regardless of the AM bandwidth selected. Competing designs ‘throw away’ bands as
the bandwidth is decreased leaving fewer and fewer bands to condition the audio for
transmission. Since it makes sense that as bandwidth is reduced more processing ‘help’
is required in order to keep the audio sounding good, the Vorsis method appears superior.
This innovative design allows for far more flexible peak control, as well as audio tailor-
ing, than the antiquated limiter algorithms with fewer bands found in other AM audio
processors on the market today.
The 10-band limiter is equipped with fully adjustable thresholds and attack and release
times for each of the bands. Because the AM-10HD’s limiter operates with precision,
time-aligned bandpass filters, regardless of its configuration due to reduced bandwidth
its dynamic operation is nearly invisible to the ear. The resulting on-air sound can be
carefully tailored to create exactly that desired.
Utilizing 10 bands of peak limiting in the AM-10HD and reconfiguring them on the
fly as AM bandwidth is changed allows tuning flexibility previously unheard of in any
AM broadcast audio processor.
The AM analog signal path is equipped with an adjustable diversity delay of up to
ten seconds corresponding to the requirements of the North American (iBiquity®) HD
Radio system.
Rack Mounting
The AM-10HD is designed to fit into an industry standard 19” equipment rack, and
requires two rack units (3.5 inches) of vertical space.
The AM-10HD does not have top or bottom cover vent holes. Latent heat is vented out
of the enclosure by natural convection through slots in the top of the rear panel. Cooler
air is drawn into the unit through vertical slots positioned lower in the side panels.
There is a small fan inside the AM-10HD whose purpose is to stir air inside the en-
closure. It does not “remove” heat. In the unlikely even that it should happen, failure of
the fan will not compromise the operation of the AM-10HD.
