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Old Sennheiser MD 421, version/wires...? With PICTURES!
Old 15th June 2019
Here for the gear

Old Sennheiser MD 421, version/wires...? With PICTURES!


I have an old Sennheiser MD 421 microphone and I could use some help. My goal is to understand this microphone so I can get an adapter cable and end up with a fully functioning mic.

Basically, all I know about it is it's an old MD 421. The little plate with the model name is missing, but it has the "klein tuchel" connector so I am assuming that it's either the "N" version or the "HL"/"HN" version with the varying impedance.

So, in order to find out what I have I started taking it apart. When I took out the connector part to look at the round metal thing for a model number there it seems to only say "MD 421." but it's a little bit hard to make out.

When I looked at the wiring inside the microphone there seems to be only two wires soldered to the connector part, one red and one blue. This makes me a bit suspicious. I don't know that much about electronics and microphones really, but I thought that these were supposed to be balanced microphones, so shouldn't there be three wires and not two? One hot, one cold, and one ground?

So basically I have two questions:

1) Can anyone tell if this is the "N" or "HN"/"HL" version of the microphone?

2) Is there something wrong with the wiring inside the microphone, like it missing a ground wire? Based on what I've read I would have expected it to have a black wire for ground in addition to the red and blue ones.

I tried attaching some pictures of the microphone that I hope can be helpful.

Appreciate any help
Attached Thumbnails
Old Sennheiser MD 421, version/wires...? With PICTURES!-421-2.jpg   Old Sennheiser MD 421, version/wires...? With PICTURES!-421-3.jpg   Old Sennheiser MD 421, version/wires...? With PICTURES!-421-1.jpg  
Old 17th June 2019
Gear Guru
John Willett's Avatar

I have just sent you a PM with a link to the 421 service manual.
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