Transmit audio phase with AM mode

N7AIG

There really haven't been any standards defined for transmission. Too bad really. Everyone has different hearing characteristics, some of us worse off than others. If a standard spectral profile could be adhered to, then each of us could create personalized listening profiles to accommodate our individual hearing.

As it stands I always listen through a MOTU equalizer, and I generally throw away anything below about 150 Hz and notch out 1 kHz with a dip. 1 kHz is an island of sound known as the "pain frequencies". 1 kHz is the sound of the roaring crowd in a football stadium. And that band lies between the first and second formants of human speech, which are the frequency bands in which our vocal tracts resonate and convey speech power.

But I do find myself having to frequently make adjustments, especially in the treble region as different guys come on the air. If there were a standard transmission profile, then this would happen. And listeners could tune the sound for their preferences once and for all.

Since nothing of importance is conveyed by transmitting your bass - remember my brain manufactures the missing fundamentals - it becomes a waste of your transmitter power to send them along.

I run Earthworks microphones in my shack, I think it is a M30, tailored with the MOTU ahead of the rigs.

Mark-NA6M

Howdy Folks,

I took a look at this today on the shack 6700 using a 1kHz sine wave as well as a Heil PR-781 Microphone feeding the balanced input. I will test again tomorrow using a 6300.

Here are some photos.


Unmodulated Carrier - 3.20 vpp


100% Modulation - 1 kHz Sine Wave - 6.08 vpp


'Hello' 100% Modulation - 6.16 vpp


Yes, over driving the modulator...

73 de na6m