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9.6.4 MORE TREBLE (HF)
There are several ways of increasing the HF content of the audio. When processing for
AM we need to use distortion controlled clipping to preserve as much of the high
frequency content as possible, which will be removed by the de-emphasis curve in the
listeners’ radios. The ‘HF clipping’, band 'drive' and ‘peak attack’ controls govern the
amount of high frequency distortion-controlled clipping that is performed.
Multiband AGC:
Increase the drive to the AGC band 4;
Speed up the AGC band 4 release time;
Lower the band 4 gate threshold, allowing more gain to be
applied to low level HF waveforms;
Consider 'force gating' the AGC band 4 so the multi-band
AGC for band 4 is bypassed.
Multiband Limiters:
Increase the bands 5 and 6 limiter drive;
Slow down the peak attack time for bands 5 and 6 and
speed up the peak release time;
Reduce band 5 to band 6 coupling;
Set the HF clipping control to higher numbers - which shifts
control from the limiters to the distortion-controlled HF
clipper.
In all processor adjusting, we suggest only small modifications from factory preset
settings if you are modifying lots of the parameters. If you are adjusting only a couple
from the above suggestions then you probably have a bit more leeway.
It is very easy to lose your way once you start 'tweaking' lots of different settings!
