Anybody knows this capsules ? Sennheuser MD421-hack-apart !!

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[silent:arts]

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capsules.jpg


I have a bunch of this capsules but know nothing about them :evil:
obviously they are dynamic and I was told the bigger ones are MD421 capsules ?

*** edited the subject ***
 
The larger capsules appear to be Philips-AKG capsules (IIRC).

I have one of these somewhere. The MD421 is probably vented at the back with a tube or similar (again, I could be wrong here - someone else can confirm).

You can remove the metal plate from the front by the way.

I would guess the smaller ones are AKG too.

They are likely to be 50 or 200 Ohms.
 
Hey Volker, I have around ten of the bigger capsules lying around and also had no clue what to do with. But now I hear 421??? I guess I have to tear one of my 421s apart to find out if it´s true :twisted:
 
[quote author="jensenmann"]Hey Volker, I have around ten of the bigger capsules lying around and also had no clue what to do with. But now I hear 421??? I guess I have to tear one of my 421s apart to find out if it´s true :twisted:[/quote]
Jens,
if you could do this ... I sold my 421s a few weeks ago, otherwise I would do it.

do you have the capsules from anywhere around the SWR ?
 
do you have the capsules from anywhere around the SWR ?
:cool: :green: :thumb:
gut geraten
:green:

I´m not at home at the moment but I´ll throw the result in here as soon as I can find some time to hack a 421 apart. Do you have spareparts left? I have a very old one with a broken locut. It´s the version which had only one locut frequency.
:guinness:
 
Are the 421s not an absolute bastard to open?

I still can't work out how to take it apart! I know how to take the bass roll-off filter out but that's it.

I will try and find my capsule which looks the same as the large one. It was taken from a Philips mic made by AKG. It has two solder-tags from the coil and one earth solder-tag which is held on by the metal resonator-cap.
 
Here we go with the final Sennheuser MD421-hack-apart-action.
First thing to do is to remove the sign with the serial number. This leads us to a screw:
normal_MD421-1.JPG


Remove the screw and tear the swith/connector thingy out of the body. Watch the cables, they are fixed with silicon and are very short and fragile.
normal_MD421-2.JPG


Deep inside the body you will find a nut. This nut attaches the grille/capsule unit to the body. Remove the nut with a 7mm Steckschlüssel (sorry, didn´t find the right word in english, it´s the tool in the picture above). Pull the grille/capsule carefully out of the body, just as far as that you can open the four screws which hold the grille on the capsule. Again cables are fixed with silicon and very short, be careful.
normal_MD421-3.JPG


The last of the four screws holds the wiring shield and is fixed with silicon/laquer. Remove all four of them.
normal_MD421-4.JPG


Remove the grille.
normal_MD421-5.JPG


Another view on the capsule (obviously it´s a different capsule than Volker posted here :cry: . Maybe I should hack a 441 apart, too :roll: )
normal_MD421-6.JPG


Opening the switch the hard way. Yes, this is CJ-style :twisted:
normal_MD421-7.JPG


On the following pics you can see the halfway opened switch unit. You can go further by removing the tiny bolt at the left end of the unit which I didn´t do.
normal_MD421-8.JPG


I hope this helps but I should mention that I did this with a dead mike. I don´t know if it´s not even more dead now. :grin:

:guinness:
 
[quote author="jensenmann"]
I hope this helps but I should mention that I did this with a dead mike. I don´t know if it´s not even more dead now. :grin:
[/quote]

I want a steckschlüssel!

Anyway, Jens, what is wrong with the mic?

Faulty capsule?? I have one in similar condition - I just can't get any sound out of it. I bought it from a guy in Germany who said that the output connector was faulty...... I've fixed that, but still no sound.... Uh oh.

It's an impressive microphone though - you can see why they cost so much. Interesting too seeing all of the venting and tubes, (resonators, dampers), etc.
 
I had a broken MD421 once.
I removed the switch thing with the trafo.
Works again now.
I hope I didn't changed anything vital to the sound with ripping it out ? :shock: :shock:
 
> Remove the nut with a 7mm Steckschlüssel (sorry, didn´t find the right word in english

Google says "box spanner". We don't have "box spanners" in the USA; I would call it a Socket Wrench. In this case, a socket wrench with a long extender to reach up inside the mike body.

Your L-shape tool is nice and simple. There are also socket-sets, with several sockets, extenders, and handle.

Or as Svart says: 7mm nut-driver.

7mm is a bit less than 9/32", a really odd size. Might be time to buy a set of French-size wrenches: at least they are now readily available in the USA.
 
[...]French-size[...]
:shock:
...interesting, i never heard this as an english word concerning the metric system...is it somehow idiomatic, like the german word "Engländer" (meaning the tool, not the person)?

Very cool pictures, i never thought of a screw under the serial number and wondered if anyone ever opened a 421 after taking a look at them in a local studio...i never owned one...
 
[quote author="John Travolta and Samuel L. Jackson in Pulp Fiction"]
Vincent: And you know what they call a... a... a Quarter Pounder with Cheese in Paris?

Jules: They don't call it a Quarter Pounder with cheese?

Vincent: No man, they got the metric system. They wouldn't know what the fuck a Quarter Pounder is.

Jules: Then what do they call it?

Vincent: They call it a Royale with cheese.

Jules: A Royale with cheese. What do they call a Big Mac?

Vincent: Well, a Big Mac's a Big Mac, but they call it le Big-Mac.

Jules: Le Big-Mac. Ha ha ha ha. What do they call a Whopper?

Vincent: I dunno, I didn't go into Burger King. [/quote]
 
> i never heard this as an english word concerning the metric system...is it somehow idiomatic

Just literal history.

The American Revolution threw-off the King. Then a few years later we sent-off to England for a copy of the Imperial Yardstick, the official reference based on the length of a dead king's foot. The US Revolution was about Trade (freedom? bah!), there was a lot of goods flowing back and forth, and we needed to be working off the same reference so trade would be smooth.

The French revolution threw-off their King AND his foot. They collected measurement experts, proposed a standard based on the (wrong) distance from Paris to the North Pole, and put two scratches on a 4-foot stick they kept in the basement. Also derived the Gram and other units from the Meter and standard density etc. A totally new system instead of the hodge-podge of old measurements of uncertain origin and inexact size. Also declared that sub/super units would be power of 10, not 8 or 12 or 16 or 5280.

Not only is it a slick system, it evolved with the best measurement technology of the 1800s.

Remember our Imperial Yardsticks? Everybody who tried to convert Yard to Meter got a different number. Starret used something like 2.5432 cm per inch, but others disagreed. In the late 1800s the three Imperial Yardsticks road-toured the several major measurement authorities, and were found (with late-1800's technology) to be different! After some discussion, it was agreed that "2.54cm/inch exactly" did not DISagree with any Yardstick more than the three Yardsticks disagreed with each other. The US officially made "2.54" the base length of the US measurements, which effectivly put the US on the French standard. We got our Official US Inch from a stick in a Paris basement. Their stick (and stick-comparision microscope) was better than the English 1700s technology. By the late 1800s, it mattered. (The UK also moved to French/2.54, though I'm not sure when. In the 1970s(?) they went All Metric for all but the most traditional trades. Can you still get a Pint of ale?)

The French kept improving, found a MASER and a number of atomic vibrations that was essentially the same as the Meter Stick but more stable and easier to read very small. So the old Meter Stick is obsolete, but played a key role in converting the World to French Measurements. (Even if, in the US, we still disguise it with 2.54 and 12 and 36 and /16....)

Oh, BTW: the Gallon varied in the US and the UK. England in the late 1700s had a corn (dry) gallon, a wine gallon, and an ale gallon (and several others, with many changes over the centuries). In 1824, GB redefined the ale gallon as the Imperial Gallon and abolished the others. We in the recently-revolted US did not get the memo and continue to use the wine gallon (though now based on the French Stick) to buy gasoline. We also get 16 liquid ounces instead of 20 ounces to the pint. http://en.wikipedia.org/wiki/Gallon
 
Thank you, Sir, for this excellent historic excurse! :thumb:
I never read the whole story behind it, as the metric system is very natural to us central europeans (and we are very sorry for the island europeans that keep stuck on their own system... :wink: ).
Interesting as ever, especially for me as a former physics student...
I'm very happy not having to deal with all that kinds of miles/pints/gallons/inches. Cool we have the same time measurement system, but that's a whole other story indeed (and not less interesting i guess...) :razz:

Kind regards

Martin
 
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