[amsat-bb] Re: Pin assignments on a stereo mic input?

Bill Acito W1PA w1pa at hotmail.com
Tue Aug 2 10:32:39 PDT 2011

I think I figured this out. Everything is wired correctly (see below). The 
issue is that the recorder has an extremely wide dynamic range,
handling line level to mic input levels. It appears that the "AGC" looks at 
both channels, and adjusts both based on the "loudest" --- so
if I have a large audio line input on one side (R), and a small mic input on 
the other (L) , the gain is set for the line and suppresses the mic into the 
If I turn the volume down on the HT audio, the mic input comes up out of the 

So I need a better, adjustable "pad" for the line level audio coming from 
the HT (better than the attenuating patch cable I am using)--  I was 
thinking of a "pot" divider with the input on the outer terminals, and the 
output off of the center pin---  should I use a big (100K) or small-value 
(100) pot? Linear, audio, or log taper?


-----Original Message----- 
From: Bill Acito W1PA
Sent: Thursday, July 28, 2011 4:55 PM
To: amsat-bb at amsat.org
Subject: Pin assignments on a stereo mic input?

One more for today...  I am using a stereo digital recorder for logging. It
has a stereo 3.5mm mic socket.
I am using a "attenuating" patch cable from the HT audio into a "stereo
splitter" plugged into the mic input
(it has a stereo plug, and two mono sockets ---  tip and base, and ring and
base). The other side of
the splitter has a mic.  So the intent it to put the HT into one channel,
and the external mic (recording me)
into the other channel, when recording.

I am only hearing the HT audio on playback. I have a feeling that the plug
"base" connection is not ground --
it is on the ring or tip.

Any one have or know the signal assignment on a recorder mic jack?  base,
ring , and tip?  I would assume
it would also match the assignment of the mic input of a PC (if you know


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