Sennheiser MD 21 help

T

tva1310

New member
Good day everybody!

My grandfather gave me his old Sennheiser MD 21 microphone (he bought it in the late 1960s). I tested it, but it appears to be broken. The cable is broken, I think. My grandfather already had this problem and tried to fix the cable. It looks like somekind of Frankenstein cable, with a logic board in the middle. I searched the internet but I couldn't really found a good answer. The only thing I know, is that the logic board is for switching from balanced to unbalanced output / balanced to balanced output.

IMG_20170520_113448.jpg

My question: Is the microphone going to work with a brand new, of the shelf cable? Or do I have to resolder cables to the logic board?

IMG_20170520_113528.jpgIMG_20170520_113515.jpg

Thanks in advance! :)

PS: Sorry if I sound like a noob. I don't really know much about microphones.
 
Have your tried contacting Sennheiser directly?

There's some older tech there that will probably be able to identify and provide more info on the mic and how to fix it or replace the cable.

Send them an email and see what they say. :)
 
It has a logic chip ? I'm not sure why he would bother ? It all looks like before chips
 
Hi,
Does the blue outer of the 1/4" plug screw off? If so, I'd screw it off and check that the solder points haven't broken away.

I'm not sure about this DIY balancing thing - As far as I know all MD21s would have balanced output anyway, and can be wired directly to XLR for use with modern mic preamps.
The connector on the mic is called Klein Tuchel and you should be able to find a KT to XLR adapter or cable online, if that interests you.
I bought two for my MD421-n microphones.

Can you show pictures of what's in that logic board thing? It's Sennheiser branded, at least. Is there a switch on it?

If you have a multimeter you could set to resistance and test across any pair then any other pair of the three pins on the mic body.
If the coil is intact, one of those tests should read some resistance.
 
Miroslav, Steenamaroo and garww; first of all, thanks for answering! :)

Miroslav: I will see if I can contact Sennheiser, thanks for the reply.
garww: Not really a logic chip (didn't exist back then), it looks like some kind of shell with underneath a capacitor I think? I don't really know much abut electronics X). But thanks for answering!
Steenamaroo: The solder points are still intact. Yeah the mic has balanced XLR output, but if you want to switch, to jack that's the way to go (I don't really care about outputs). I did ask my grandfather and he swears that the balancing board should stay connected, not really sure why tho. Because for an XLR cable you don't really need that board, because you're not changing the cable, right?
Inside the plastic case is somekind of metal protection, I cannot get it off. My guess, is that the wires go from XLR to jack like somekind of switch. Also thanks for answering!
IMG_20170522_081334.jpg
 
tva1310 said:
Inside the plastic case is somekind of metal protection, I cannot get it off. My guess, is that the wires go from XLR to jack like somekind of switch.
Click to expand...


That's why you should contact Sennheiser....they are very helpful...rather than bouncing around the internet.

I had some problems with a U441...something with how the capsule was mounted and the switching...and one of the techs gave me all the answers, provided instructions and also pictures, since there were different revisions to the internal housing, and he told me what to look for so I could identify things correctly...and what to watch out for so as not to damage things.
 
A better picture of the connector on the mic would help. The version without the exposed threads is a three pin connector, similar to an XLR but smaller (Klein Tuchel rather than the three blade Tuchel on the version with the threads?). It can be wired directly to an XLR, KT pins 1, 2, 3 to XLR pins 2, 1, 3, according to the page below.

The component in the box is almost certainly a transformer adapting it to high impedance unbalanced use. Visible are three wires, red, black and uninsulated. The uninsulated one is the ground, the other two are the hot/cold. An XLR is wired 1 ground, 2 hot, 3 cold. That should give you enough information to confirm the pin to pin advice in the linked page, with the worst case scenario being swapped polarity.

Sennheiser MD21 wire diagram - Gearslutz Pro Audio Community
 
bouldersoundguy said:
The component in the box is almost certainly a transformer adapting it to high impedance unbalanced use.
Click to expand...

That seems much more likely.
I really think you just need a straight up klein tuchel to XLR adapter - same as my 421-n microphones.
If you need 1/4" plug then Klein tuchel to 1/4".

The latter will be unbalanced, but there's no need for anything in between if you're using a modern recording gear.

What's your intended use?
 
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Well, its all right there. Other than the short in the capsule, its just looking after the wiring
 
Hey Arcaxis,
Admin are aware of this. I'll report this as a reminder, though.
Thanks.

Edit: I just realised you were uploading PDF. I'm not sure that was ever supported.
I'll ask about it, though. :)
 
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Thanks for answering! :)

Miroslav: I'm surely going to contact sennheiser, thanks again!
Bouldersoundguy: Thanks for the all the info, I will look into that! A better picture =>
IMG_20170522_182845.jpg
Steenamaroo: I will look into the tuchel to XLR adapter. Intended use: recording some vocals, nothing special. It will probably end up straight into the mixer.
arcaxis: Thanks for the info!
 
Fair enough.

I hope the mic works! If you're even half way handy it wouldn't be too hard to prove it, if you want to know before spending money.
If not, good luck and please let us know how you get on. :)
 
If I had that mic I'd de-solder the cable from the box and connect it to an XLR with alligator clip wires to test it. Actually, you could probably clip on to the cable's conductors without de-soldering it. Or just clip to the pins.
 
Having owned a number of MD21 mics (I believe that I was the first person to use Sennheiser mics in Australia), much of the information supplied above is unfortunately incorrect.

The connector on the mic is NOT a Tuchel but rather a 180 degree 3 pin DIN connector and as the mic is fully balanced all that the original requester has to do is to get the 180 degree 3 pin DIN female socket (be careful there was/is also a 180 degree Din connector and they a re not interchangeable). The active pins are Pin 1 and Pin 3 with Pin 2 being ground/shield.

When buying the DIN connector, I would suggest trying to get a screw-on version rather that the non-screwed (ie push in) version as it make the connection between the mic and cable far more secure.

You will not need to use the adaptor unit unless you are plugging the mic into a 1/4" unbalanced mixer/amplifier/etc, but you could also do this by un-balancing the XLR plug (but definitely not ideal).

Below is the full wiring for the DIN and XLR plugs (thanks to Gear Sluts --- saves me having to type it !!!).



The connector is a standard female 3-pin DIN plug and is wired as below:-

Pin-1 = +ve
Pin-2 = screen
Pin-3 = -ve

and for the male 3 Pin XLR - this would be wired:-

Pin-1 = screen
Pin-2 = +ve
Pin-3 = -ve

BUT BEWARE - the pin layouts is different.

In a DIN, pin-2 is the middle pin.
In an XLR pin-3 is the middle pin.

Hope the above helps.

By the way, A DIN plug is about 1/2" diameter while a Tuchel is much heavier and is about 1" diameter and screws on rather than being pushed in.

David
 
...from Sennheiser's literature.
Screen Shot 2017-05-29 at 04.22.05.png

There exists a large and small tuchel. It sounds like you're describing the large one?
This mic has the small one.
 
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