Dear amigo: After running many tests... we found out what may best be described as an almost optimum setting of the audio frequency response curve that will provide my listeners with the best possible audio ¨punch¨, that is audio that will get trough interference of all kinds... As a bonus, if you remove the lower frequency segment of the audio , that is from 30 to 250 Hertz, your transmitter won´t waste power modulating that segment of the audio spectrum that provides, according to psychologists and audiologists, practically no useful information for the human to decode voice. Although of less significance, it is also a good idea to introduce a high frequency cut with a 12 or 18 dB per octave slope after 2.7 kilohertz or so... I have heard my shows on short wave under the most difficult reception conditions and the programs came in a lot better than the other shows recorded with the ¨standard¨studio quality. I am sure that you are aware that the typical short wave broadcast transmitter´s audio frequency response curve starts around 50 Hertz and ends quite abruptly at around 4.5 kiloHertz with a very steep slope that is required in order to comply with the channel separation requirements... The studio microphones, audio mixers, master control program amplifiers, fiber optic coders and decoders, STLs etc. are alway easily capable of handling a minimum bandwidth of between 20 and 15,000 Hertz... while the short wave transmitter by its own nature is only cable of responding from about 50 to 4500 Hertz... and if you really want to be heard under the most difficult reception conditions, your voice modulation should be restricted to the range between 250 and 3000 Hertz or so... 73 and DX YOur friend in Havana Arnie Coro CO2KK Host of Dxers Unlimited radio hobby program Radio Havana Cuba
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