— 40 —
sure listen with monitors that can reproduce the affects you are
dialing-in!
Another tip is, like the Stereo Enhancement utility, use the Bass
Effects: Active/Bypass switch to preview the action of this fea-
ture.
There is one caveat with respect to the bass enhancement sec-
tion, one that is hinted on the Block Diagram (Page 10). Bass ef-
fects are added back into the multiband mix at the input to the
peak limiting section, bypassing the Multipressor. ‘Enhanced’
bass energy will not be subject to compression before it hits
the peak limiting section, and huge amounts of bass may cause
some degree of broadband-limiter ‘ducking’ as a result. Listen
for this and trim your adjustments accordingly.
PROGRAM PEAK CONTROL
Broadband
and HF
The broadband peak limiter acts on program audio that is de-
livered to any of the unit’s outputs, whether it’s a flat, 20kHz
signal for digital broadcasting or other full-power-bandwidth
application, or for FM transmission. But FM transmission re-
quires additional processing to restrict energy in the pre-
emphasized portion of the spectrum. This is provided inde-
pendently by the adaptive pre-emphasis stage that follows the
broadband limiter, and is active only for FM transmission.
Broadband limiting and adaptive pre-emphasis will be dis-
cussed separately.
BROADBAND LIMITING
PIPP* Limiting
PIPP* is an acronym for
Polarity-Independent Peak Processing
,
Inovonics-patented and proprietary technology used in both
analog and digital processing products from our firm. This is a
function that can be turned on or off by the user and, when it is
disabled, the DAVID IV peak controller behaves much like any
contemporary “lookahead” limiter.
In the PIPP* mode, the program audio waveform is split into
positive-going and negative-going components. Each half of the
waveform is then independently limited to a peak value that
corresponds to 100% carrier modulation in its respective direc-
tion, and then the two components are recombined. The pur-
pose of this somewhat roundabout exercise is to maximize car-
rier modulation regardless of waveform asymmetry.
The initial response to this elementary explanation is generally
one of astonishment that such a degree of “distortion” would
deliberately be introduced, much less tolerated. Please allow us
to debunk this knee-jerk reaction.
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