A few comments about audio and mikes. It greatly concerns me when one
references "setting a knob to a certain position" i.e. 9 o'clock, 11
o'clock or 3 o'clock or whatever, purely based on past experienced with
different models of radios. Each radio and its audio path and each mike
along with the way it is used and the loudness of the voice in front of the
mike will demand different mike gain level conditions. Some people have
more "power" in their conversational voice and thus mike gain values will
need to be changed to account for the deep voice of a male compared to a
higher pitch voice, one containing less power, such that of a female for
example. To that end, and in unrealistic terms, if all radios were alike
and all mikes were alike there would be no need for a mike level control.
Now with that said, we know that isn't the case and thus the reason for the
mike gain control, among others.
It is more of a concern that one adjusts the mike gain correctly based on
the mike, the radio, the voice and etc. The difficulty is determining the
point or value of "correctly". With most radios today, adjustment of the
mike gain is done while monitoring some level type indicator, be it an ALC
LED or ALC Meter or ALC bargraph. There is a correct adjustment value to
be attained and done so by using a procedure as defined by the manufacturer.
No amount of tweaking and solicited on air reports will produce anything
with any valid meaning. With the mike gain correctly adjusted I rarely if
ever ask for an "on air" audio report. I frankly see no value in such
unless one's ego needs nutrition. To that end, the receiving conditions,
the listener, the receiver, the speaker, the listeners room acoustics and a
host of other things can and does affect the perception of the quality at
the other end. Just too many variables to equate.
Don't get me wrong, I do care greatly about my transmitted audio and go to
great lengths to assure it is of good quality. I rely primarily on two
factors. If someone, during a QSO, voluntarily says my audio is good (and
it does frequently happen) then I'll accept the fact that the audio is good.
On the other hand, and it has happened recently, someone that knows me said
my audio was not good and they went on to describe what they heard.
Investigation on my part determined that a connector from the computer to
the radio had become partially unplugged and thus RF was getting into the
mike audio. Frankly, although unaware at the time, I am sure that it
sounded bad and thus the listener reported such. In both cases the reports
were "unsolicited" and considered as accurate by me.
I've found that most Tentec hand mikes sound about the same and have about
the same output level. The same holds true for the 705 series of desk mikes.
As to others, mikes of the same series by today's standards will perform
very close to the same, comparing mike to mike of the same brand and model.
The basic reason for using different mikes, in my viewpoint, is largely a
matter of convenience and to some degree a desire to achieve a different
sound for some specific reason. I like the dynamic mikes for my AM
operation because of the increased "bottom end", the result of the close
talking proximity effect which will boost the lower frequencies. At the
same time, the use of the large diaphragm condenser mike produces a wide
crystal clean smooth response extending well below and above the limits of
the human voice. For the limited response of SSB, one may tailor their
response with mike selection for casual QSO operation or one for screaming
pile up busters for chasing DX. It's your choice. Heil has selected mike
models that will favor either desired mode of operation. In day in and day
out operation the Tentec 705 desk mike is hard to beat for great audio
quality on one of Tentec's current radios.
As to using meters to judge power output, and worse trying to adjust mike
gain, please understand that the ballistics of a meter will almost totally
determine how much deflection will take place based on a complex audio
waveform such as speech. Again, in my case, I have a true peak reading watt
meter and an average reading power watt meter. They show vastly different
values on speech while being used at the same time on a given transmitter,
but identical values on a sinewave tone and identical values in the TUNE or
CW mode. (I dare not broach the wall of PEP meters and definition of power
in this discussion.) Once an audio stage is driven into distortion or an RF
stage is driven into distortion the average power rapidly increases and is
thusly indicated as such on the average reading meter. This is viewed as
"not good" in most circles and one likely will hear about splatter being
generated from their neighbors on the band.
Unless one has actually measured audio input level and compared that to
transmit power output and then understands that, in radios of different
models and or makes, the mike gain control can be logarithmic, log
logarithmic, anti log or linear and if the mike gain control is used as an
attenuator or is used in the feedback loop of an opamp thus controlling
actual stage gain, then the expression of rotation in terms of a percentage
is totally useless. I don't mean to poo poo on any ones picnic, but we do
need to better understand the application, so to speak, before we get overly
concerned of just what position the mike gain control is located.
(Translation: it's not important.)
More importantly, in simple terms, adjust the mike gain for the correct
value of indication on the device provided in the radio by the manufacturer
using the procedure specified by the manufacturer. That's all there is to
solving the problem.
73
Bob, K4TAX
P.S. - So I'm long winded, I do work AM. If you'd like more dialog on this
subject, a private E-Mail to me at RMcGraw@Blomand.net will get an answer.
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