[Elecraft] Vocal Cord Bias + SSB PEP

[Jim Brown]

Yes, it's long been well known that real audio waveforms are 
asymmetrical. WAY back in the '50s, AM broadcasters used a device that 
constantly monitored the waveform and constantly flipped the polarity to 
keep the hottest peak so that it increased instantaneous TX power.  
That's because with AM, distortion is created at carrier cutoff.  I 
remember building a negative peak clipper circuit back in the '50s.

Here's an AES paper by R A Greiner (and probably one of his EE students) 
that studied the audibility of absolute polarity (that is, the same 
polarity in the playback system as in the recording system).
http://www.aes.org/e-lib/browse.cfm?elib=6950 Several recording and 
sound engineers who were members of a professional organization called 
SynAudCon demonstrated that they could accurately tell by listening 
whether the polarity of a system was correct.

Note that we're NOT talking about polarity difference between channels 
of a stereo recording.

73, Jim K9YC

On 9/14/2018 2:13 PM, Bob McGraw K4TAX wrote:
> From my AM broadcast days and my pro audio days, yes it is not unusual 
> to find that a given mike has more positive output than negative 
> output in terms of the voltage waveform.