While James and I do generally concur on test and evaluation methods, I
would comment I've found the input impedance of the specific device {radio}
will have some effect to significant noted effect on the sound of a given
microphone.
While the radio may indicate an input impedance of 10 k ohms at 1 kHz, then
one might ask what is the input impedance at 300 Hz. or some other
frequency? Another model radio specification states "Microphone Input:
200 - 50K ohms" and then another model radio states "Microphone 2 K ohms -
condenser". These numbers range from 200 ohms to 50 K ohms.
My point, a given mike that may sound good on one radio and may not sound
good on another for the reason that the input Z of the radio mike circuit
will have a noted effect on the dynamic response of the mike of concern.
Hence my basic reason for using the mike of choice on the radio of choice
for performing critical evaluations.
Once done, I believe the method suggested is sufficiently accurate and
repeatable, that on-air "how does my audio sound" is a mute point. Besides
you have no idea of how the station on the other end has their receiver
configured nor of their listening conditions.
73
Bob, K4TAX
----- Original Message -----
From: "Richards" <jrichards@k8jhr.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Tuesday, August 26, 2014 5:24 PM
Subject: Re: [TenTec] Mike & Eagle
I do something similar to Bob's test procedure - I test every microphone
on my computer FIRST - because I figure if it sounds crappy on the computer
it is likely to sound crappy on the rig. But Bob's further on-air test is
a swell way to make sure it not only sounds OK on the rig, but confirm your
speech processor, EQ, and other settings are in order, as well.
My test protocol is similar to Bob's - he is the expert, so ultimately
listen to hims... set the transceiver to Flat EQ, and no speech
processor, and transmit into a dummy load. I employ one of my SW
receivers (usually a Kenwood R2000) which has a LINE-OUT signal that is
plugged directly into the LINE-IN input on a computer sound card. The run
the receiver with no antenna, or maybe just a short hank of wire, to avoid
overload, or I use a receive only antenna located in my front yard, far
enough from the transmit antennas, to avoid overloading it, and record
what it hears. Only after I am satisfied with this result do I mess with
EQ and speech processor settings.
I also get a couple of local hams monitor and record my signal. I
distribute a really small recording applet to minimize variations, and
figure most sound card DACs are consistent enough for Government work. Not
as exacting as Bob specifies, but I don't worry about variations in DACs.
;-) I don't mess with the "reference" sample, but that may be a good
plan to assure the recording process is accurate in the first place -
kinda like measuring a control group against the experimental group.
Anyway... just my take...
------------------ K8JHR --------------------
On 8/26/2014 8:30 AM, Bob McGraw - K4TAX wrote:
Yes, the connectors are "tight" in terms of working space. Too much
heat, i.e. too large of a tip will transfer too much heat and things
begin to melt.
For audio quality determinations, I prefer to use the "comparison"
method. I'll outline my method. This does require two suitable radios.
Having the "monitor" radio being the 2nd radio connected to the computer
for digital modes, I use that signal path along with a free software
being AUDACITY to record the audio. I first find a signal on the band
that I think sounds specially good and I record about 30 seconds of that
signal. That becomes my "reference" signal. I also use external
speakers on the computer and listen to both the reference signal and my
test signal through these speakers. Remember, the path much be
identical for accurate comparisons.
Now using the mike and radio of choice on a dummy load, same mode,
frequency and such. I transmit about 30 seconds while recording that
transmission and then listen to it and the other signal. AUDACITY
allows one to easily switch between the two recorded segments. By
doing this one is using the exact audio path, computer, speakers and
such to judge ones audio. If it doesn't sound as you wish, then
adjustments of any nature should be made. This includes mike-to-mouth
position or changes in audio levels, speech processing or even changing
mikes. Again repeat the process and each time a change is made and
compare the new configuration to the reference signal that one thinks
sounds specially good.
Now admittingly, ones personal voice will not typically sound exactly
like another's voice, but one can easily discern the differences. When
finished, just note the various values on the radio, the mouth-to-mike
position and such. From this one can be quite reasonably assured their
signal will always sound great on the air.
In using this process, if humm, clicks, buzz or such is heard on the
comparative recordings, the source should be investigated and resolved.
I will stress that using the Monitor mode or headphones while recording
ones audio will not accurately reveal the true audio sound.
73
Bob, K4TAX
----- Original Message ----- From: "John Farler" <k4avx1@windstream.net>
To: <tentec@contesting.com>
Sent: Monday, August 25, 2014 8:57 PM
Subject: Re: [TenTec] Mike & Eagle
Thanks for confirming what I've tried. I think I'd better go
back and check that 8 pin connector pin-out again. For
this old guys hands and eyes, I wish they had stayed with
the 4 pin connector :>)
The mini-din on the back caused me much grief. It wanted
to melt - wonder if it came from radioshack!
And yes, I was told that the headset mike I was using
on the OMNI 6+ sounded as good as the TT desk mike with
the same kind of element. Ear piece quality is a consideration.
73,
John, K4AVX
Message: 3
Date: Sun, 24 Aug 2014 16:23:44 -0400
From: Richards<jrichards@k8jhr.com>
To: Discussion of Ten-Tec Equipment<tentec@contesting.com>
Subject: Re: [TenTec] MIKE & Eagle
Message-ID:<53FA49D0.1040205@k8jhr.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
John --
My test for mic quality is to make a recording on the computer using a
low sampling rate, maybe 11.5 Hz - and if it sounds OK, then it should
sound OK on the air. If not, try another model.
Message: 4
Date: Sun, 24 Aug 2014 14:16:24 -0700
From: Jim Brown<k9yc@audiosystemsgroup.com>
To:tentec@contesting.com
Subject: Re: [TenTec] MIKE & Eagle
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