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AM-10HD / Aug 2008
F E A T U R E S A N D P R E S E T S
About Bass
The AM‑10HD contains our specialized Vorsis Bass Management System (VBMS).
VBMS extracts, reveals, and then controls low frequency nuances in the incoming
program that are simply not heard with any other AM broadcast audio processor. In
fact, the way that bass is managed in our AM processor makes it a bit easier for AM
transmitters, particularly older ones, to handle without distortion or component stress.
Is There a Caveat?
Of course! It is fair to say that the majority of AM radio listeners don’t have near
the quality of off‑air monitoring equipment that is typically found at most radio sta‑
tions. Therefore great care (and we cannot over‑emphasize this!) is advised when
adjusting the AM‑10HD to accentuate the extremes of the audio spectrum.
Program energy at the frequency extremes is typically several dB below that in
the more easily heard midrange. Because of the nuances of human hearing, very
low and very high frequencies take a lot more modulation power to become audible
to the average listener. Not only that, but unlike most consumer type FM receivers,
those for AM have extremely restricted frequency response – at both ends of the
audio spectrum.
Over‑boosting of bass or treble energy that can be heard by only a small percent‑
age of the station’s audience can result in reduced loudness and/or higher distortion
for the majority of the station’s listeners. Over‑boosted bass, while also taxing the
transmitter’s modulator and power supply harder, can cause increased intermodula‑
tion distortion in a consumer’s receiver. On the other hand, over‑boosted high end
can tax components in the transmitter’s RF output network and tuning networks, and
will also make tuning into the station much more difficult for those with manually
tuned radios.
What Is Your Short Term Goal?
The usual short term goal related to installing new audio processing involves
generating large amounts of loudness in order to attract attention to the station as a
listener scans across the dial.
Almost as important as the station playing a listener’s favorite record when they’ve
tuned in, a station that’s LOUD carries with it a certain “authority” that can make
a listener stay tuned long enough to see what’s next on the playlist. As well, high
loudness on AM technically increases the coverage area by increasing the average
sideband power of the station, making it easier to listen to out in the fringes of the
coverage area.
While loudness can attract a listener, so too can it drive them away. Extreme
loudness usually carries with it forms of distortion and other artifacts that can sub‑
consciously tire a listener and make them tune away without even realizing why.
Loudness then, for loudness’ sake, must be approached with a bit of caution.
