3 pronged mike

L

Little Monster

Guest
Hello all,

I got a second hand microphone the other day for recording interesting
sounds on a little piano-key type mono tape recorder.

The mike is made by Grundig, model GDM 311 seems very well made, and looks
like the sort your parents/grandparents might have used to record baby's
words on the family reel to reel.

It has screen + 3 wires terminated in a 3 pin DIN plug, these are the
outputs from some kind of matching transformer (I had a look) a low
impedance side which seems to match the recorders input, and a higher
impedance side. (I could only measure the DC resistance though)

So what I would like to know is, why the 3 wire arrangement? Is to
provide an alternative match for a non standard input, or is it to provide
some kind of offset earth connection - I'm guessing to feed a differential
input.

Any suggestions, anybody? It would be nice to know even if I'm not going
to use the extra wire.

Tia, Monster
--
Spam will eat itself
 
"Little Monster" wrote ...
I got a second hand microphone the other day for recording interesting
sounds on a little piano-key type mono tape recorder.

The mike is made by Grundig, model GDM 311 seems very well made, and looks
like the sort your parents/grandparents might have used to record baby's
words on the family reel to reel.

It has screen + 3 wires terminated in a 3 pin DIN plug, these are the
outputs from some kind of matching transformer (I had a look) a low
impedance side which seems to match the recorders input, and a higher
impedance side. (I could only measure the DC resistance though)

So what I would like to know is, why the 3 wire arrangement? Is to
provide an alternative match for a non standard input, or is it to provide
some kind of offset earth connection - I'm guessing to feed a differential
input.

Any suggestions, anybody? It would be nice to know even if I'm not going
to use the extra wire.
Click to expand...
Some microphones I have seen have both high-impedance, single-ended
outputs AND low-impedance, balanced outputs. This was back in the
days when there were still high-impedance mic input requirements and
when the concept of low-impedance, balanced was becoming accepted
as the professional standard. The user was expected to wire the cable
to tap whichever output was required.
 
Agreed, the actual voice coil is connected to 2 of the pins and the ground
is the third. Many Microphone designs used this inclusive of Shure. Been too
many years for me to remember the configuration tho.
"Richard Crowley" <rcrowley7@xprt.net> wrote in message
news:vpjnpobdabdedf@corp.supernews.com...
"Little Monster" wrote ...
I got a second hand microphone the other day for recording interesting
sounds on a little piano-key type mono tape recorder.

The mike is made by Grundig, model GDM 311 seems very well made, and
looks
like the sort your parents/grandparents might have used to record baby's
words on the family reel to reel.

It has screen + 3 wires terminated in a 3 pin DIN plug, these are the
outputs from some kind of matching transformer (I had a look) a low
impedance side which seems to match the recorders input, and a higher
impedance side. (I could only measure the DC resistance though)

So what I would like to know is, why the 3 wire arrangement? Is to
provide an alternative match for a non standard input, or is it to
provide
some kind of offset earth connection - I'm guessing to feed a
differential
input.

Any suggestions, anybody? It would be nice to know even if I'm not
going
to use the extra wire.

Some microphones I have seen have both high-impedance, single-ended
outputs AND low-impedance, balanced outputs. This was back in the
days when there were still high-impedance mic input requirements and
when the concept of low-impedance, balanced was becoming accepted
as the professional standard. The user was expected to wire the cable
to tap whichever output was required.
Click to expand...
 
On Sat, 25 Oct 2003 08:14:20 -0400, Arthur Jernberg wrote:

Agreed, the actual voice coil is connected to 2 of the pins and the ground
is the third. Many Microphone designs used this inclusive of Shure. Been too
many years for me to remember the configuration tho.
Click to expand...
So, without removing the shield to have a look, could this be an
auto-transformer sitting in there?

Monster
--
Spam will eat itself
 
"Little Monster" <root@localhost.localdomain> wrote in message news:<d74e096d7a77cd452ff67b5d6efd60b4@news.teranews.com>...
On Sat, 25 Oct 2003 08:14:20 -0400, Arthur Jernberg wrote:

Agreed, the actual voice coil is connected to 2 of the pins and the ground
is the third. Many Microphone designs used this inclusive of Shure. Been too
many years for me to remember the configuration tho.

So, without removing the shield to have a look, could this be an
auto-transformer sitting in there?

Monster
Click to expand...
Given that most of the older Shure mics had a switch to select output
impedance, yes.

Harry C.
 
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