Slightly ill MD441

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M

mindlessstudio

Member
Joined
Oct 4, 2012
Messages
23
Hello there, returning customer after quite a few years here ... was busy, am back! :)

I've got a bunch of MD441s and one of them has started acting up. Basically, it only outputs very little, and there's almost no bottom end in it. Shaking it about a bit makes it go BOOM with loads of lows, but doesn't fix anything. I opened it up to see if its dia was easily cleaned, but it seems I have to take parts apart that I don't really know too well, so I thought I'd just hear if there's gurus in the house. A few more things: when I tap the inserts gently with a wooden toothpick (or indeed a great big hammer) it sounds exactly like you'd expect when you tap a mic, lots of lows etc. But when I speak into it, there's that almost no sound at all thing again. I've removed the (falling about) foam at the input end but since there's a grill at the end of the funnel behind it, there shouldn't be any nasty filth in the diaphragm part itself, afaik. So ... ehmn. What to do? Any suggestions are very very welcome :)
 
A classic Problem with the Senn dynamic is that they have a really small crack on the diamter of the membrane so it does not build pressure movement and the sign of this is low output and no bass,
not sure about your steps but take a magnyfying glass and try compressing the membrane with a cue tips and look at the outer edge of the mic to locate a crack on the edge if there is one you will see how to membrane does not compress equally on this side and might be babnle to locate that crack usually it is obvious,
hope this helps,
dan,
 
Hi Dan, thanks a lot. That certainly sounds like my problem – although I don't really get why there'd then be plenty of lows when I fuddle about with the innerts of the opened up mic. But - worth a shot for sure. One thing: Would you happen to know how to take the damn capsule part apart without ruining anything? It's encapsulated in a way I haven't seen before (I've only messed about with a few condenser mics before, and their membranes where pretty easily accisible. This one not so much it seems.
 
The membrane is actually glued all over the diameter no way to remove it or mean accessing senn type mic

 
Ah. So the only solution is to order a replacement capsule assembly (the front bit before the eq-module, I suppose?) from Sennheiser then? It's a rather old 441, with Tuschel connector. D'you reckon modern replacement parts will work?

God, I HATE drummers  :(
 
If You Can send me a really good photos of diaphragm at the capsule (from few point of view), maybe i can help You something.
I have big experience with old sennheisers.
There's a few typical damages, most everything is for fix.
Worst is demagnetisation, not worth to do anything. In other cases, if diaphragm isn't interrupted, it's many ways to bring mike alive
 
ln76d said:
If You Can send me a really good photos of diaphragm at the capsule (from few point of view), maybe i can help You something.
I have big experience with old sennheisers.
There's a few typical damages, most everything is for fix.
Worst is demagnetisation, not worth to do anything. In other cases, if diaphragm isn't interrupted, it's many ways to bring mike alive
Click to expand...

Hi 76, and thanks –

The thing is, I can't really figure out how to get to the diaphragm without damagins the capsule part. That whole encapsulated upper part of the innerts seems very not-taking-apart-able to me, and I don't want to mess things up. There's the white fabric at the top, then there's a black plastic 'tube' with square holes in it (that one's got some screws in it), then the harder part of the capsule begins, and then there's the coil which has wires going up to the black plastic tube with the holes. I take it the diaphragm resides inside this bit but I can't figure out how to get to it. Any hints before I ruin it completely? :)
 
Do You have good experience with soldering?
First what You can try, its desoldering compensation coil (those two soldering points on cartridge).
Then try connect in this place hot and cold leads from any microphone cable with xlr from the other side.
You can remove whole cartridge part and connect it direct to the xlr, including compensation coil, like on this photo:
http://www.gearslutz.com/board/attachments/geekslutz-forum/233006d1304360234-md441-repair-help-senn441.jpg

This will give 100% sure, that's the capsule fault, because it can be electronics faulty too.

If the capsule is faulty, try to remove this "trumpet"  tube. I really don't remember it's screwed or glued. Last time when i repaired md441 it was 7 years ago so i don't remember well, but all sennheisers in standard have glued those diaphragm covers.
You can try to use thin scalpel and undermine the side which i marked on photo.
Those glues are mostly weak - as the glue in diaphragm placement - probably problem in yours 441.

Shame that i don't have now any 441 at home, to disassemble and make good photos for you.

Remember that's the job like model making - you must be really carefull but first try to check same capsule without electronics.

 

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ln76d said:
Do You have good experience with soldering?
First what You can try, its desoldering compensation coil (those two soldering points on cartridge).
Then try connect in this place hot and cold leads from any microphone cable with xlr from the other side.
You can remove whole cartridge part and connect it direct to the xlr, including compensation coil, like on this photo:
http://www.gearslutz.com/board/attachments/geekslutz-forum/233006d1304360234-md441-repair-help-senn441.jpg

This will give 100% sure, that's the capsule fault, because it can be electronics faulty too.

If the capsule is faulty, try to remove this "trumpet"  tube. I really don't remember it's screwed or glued. Last time when i repaired md441 it was 7 years ago so i don't remember well, but all sennheisers in standard have glued those diaphragm covers.
You can try to use thin scalpel and undermine the side which i marked on photo.
Those glues are mostly weak - as the glue in diaphragm placement - probably problem in yours 441.

Shame that i don't have now any 441 at home, to disassemble and make good photos for you.

Remember that's the job like model making - you must be really carefull but first try to check same capsule without electronics.
Click to expand...

This is extremely helpful, thanks a lot!! One question: how do you get the filter-electronics (I guess that's what the metal tube is, yeah?) and the capsule itself taken apart without breaking the copper wires? Screwing them apart seems to tighten those two tiny things to their limits, so I've stopped that now ...
 
I will try help You as i can ;)
Late i'll write You how to disassembled those parts  - i  must go now.
You can try quickest option - take microphone cable with on mike side without xlr. Best will be with soldered end of the wires.
Put red and blue (or white) wire to those solder pins marked on photo. It will be in parallel connection to the rest of the circuit, so the rest of the circuit should not affect on output - in theory.
This should give you understanding what is faulty.
 
Did you tried to put wire to those solder points? Any results?
As i remember, the whole capsule cartridge should be normal unscrewed.
Try to unscrew carefully, because it's a plastic on capsule side as you know.
If it's going hard, try to unscrew, tighten, then unscrew again.
I forgot about something!!
I've marked on photo - there's a ring which should be pulled off - use thin piece of metal (like scalpel or something similar) and undermine both sides, which are bended to inside.

aaa!!
...and watch out for suspension between circuit cartridge and capsule cartridge.
 

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Good to see some use being made of those photos.  I'll try to take some better ones with a macro of diaphragm etc.. 

To get to the circuit board, I ended up putting the whole rear assembly inside of a sealed breastmilk bag.  Placed this in a pot of boiling water for ~10 minutes.  Then USING HOT PAN HOLDERS (yes I regrettably attempted to open with bare hands)  you can separate the rearmost black plastic cap from the aluminum can.

I've found a handful of 'dead' 441 mics that only had broken traces on the circuit board where the pcb was literally cracked in half.  New board installed and the mics works great.

I've found a few 441 mics with open voice coils.  I've been working on counting the windings for a couple years now (busy busy).  It should be fairly straightforward to wind and adhere a new coil to an existing diaphragm so long as the diaphragm isn't destroyed.  Or if we could get Senn and other companies to just issue the coils as spare parts, this would save me some huge headaches.

The diaphragm for this mic is an odd one.  The flutes appear very simple by design but the diaphragm material doesn't seem to be consistent.  Near the flutes is very soft and flexible, whereas the center dome is very hard ie doesn't dent or push in.  Also the edge of the diaphragm that adheres to the faceplate is very stiff.

 
MicDaddy said:
Good to see some use being made of those photos.  I'll try to take some better ones with a macro of diaphragm etc.. 

To get to the circuit board, I ended up putting the whole rear assembly inside of a sealed breastmilk bag.  Placed this in a pot of boiling waster for ~10 minutes.  Then USING HOT PAN HOLDERS (yes I regrettably attempted to open with bare hands)  you can separate the rearmost black plastic cap from the aluminum can.

I've found a handful of 'dead' 441 mics that only had broken traces on the circuit board where the pcb was literally cracked in half.  New board installed and the mics works great.

I've found a few 441 mics with open voice coils.  I've been working on counting the windings for a couple years now (busy busy).  It should be fairly straightforward to wind and adhere a new coil to an existing diaphragm so long as the diaphragm isn't destroyed.  Or if we could get Senn and other companies to just issue the coils as spare parts, this would save me some huge headaches.

The diaphragm for this mic is an odd one.  The flutes appear very simple by design but the diaphragm material doesn't seem to be consistent.  Near the flutes it feels very soft and

flexible, where the center dome is very hard ie doesn't dent or push in.  Also the edge of the diaphragm that adheres to the faceplate is stiff.
Click to expand...

I have no oportunity to make photos by myself, so i used existing from the net (those yours?).
I truly don't remember how i opened the circuit can, but if was glued, probably i used some prep for the removal of adhesive labels - bought in supermarket.
Did  you not  affraid to boil transformer/coil?
I need to look on the small cheap plastic sennheiser (if i get some in my hands), what coils they have, truly they can have same - as on many sennheisers.
On mindlessstudio 441 probably glue let go on the "edge of the diaphragm that adheres to the faceplate is stiff" - which is typical for old sennheiser - mostly in the diaphragms of md421/md409 type.
Coil should be ok.
Sometimes glue may let go in a point where the coils meet the diaphragm, but then it sounds truly sick or even no reproduce sound at all
In fact, loose of bass response - can be something in circuit too, so trying to connect only capsule should solve the puzzle.
Sorry for my english - i hope it's all understandable:)

 
Well. I got it all taken apart (wasn't soooo hard to take the black plastic cap off the filter enclosure, just a bit of a brute (yet finely applied) force, really). But. The wires are still keeping everything together, and I can't get to whereever they're all soldered on to the filter board. Do I just (gasp!) CUT them and then soldering them back together after I'm done? Sorry if I sound stupid, but this is my first mic repair, even thought I've been repairing old synths and studio gear for years and years – and it seems to be a much more delicate job, so I don't wanna mess it up.

Thanks for all your input guys, btw. Much appreciated!! :)
 
Try only stick with fingers two bare wires from microphone cable to the solder points. Nevermind if those are before compensation coil or with it on pcb.
It's less work to do. If  capsule will work normal -  it's the circuit part, if no - it's diaphragm
 
ln76d said:
Try only stick with fingers two bare wires from microphone cable to the solder points. Nevermind if those are before compensation coil or with it on pcb.
It's less work to do. If  capsule will work normal -  it's the circuit part, if no - it's diaphragm
Click to expand...

Hmm ... you mean I should just attach some cables (without soldering them) to the two copper wires after (or before) the coil and hook them up to an XLR? And then if there's sound, it's the circuit, if not it's the dia?

 
Attach - o yeah!!! That's the word  ;D ;D ;D ;D ;D ;D ;D ;D
I've tried to explain you that on a few earlier posts, but my english sucks  ;D
Yes - "attach" two bare cables (red and blue for example) to those solder points.
You can try to do that before compensation coil and after.
If you have a smooth fingers just attach and hold them, if not, you can solder them at those points without unsoldering original wires.
When you attach them, the rest of the circuit shouldn't affect on the output sound.
It's better to put some tin on those bare wires before attaching them - it's much easier.
 
OK, I tried soldering a couple of test cables directly onto the solder points going out of the dia towards the coil – and there doesn't seem to be any difference: I get sound when I touch the capsule enclosure and the white fabric at the very top of it. You know, the sort of sounds you'd except when touching any part of a microphone. When I swipe my finger round the edge of the withe fabric, it sounds completely like you'd expect a mic to sounds, when sweeping a finger across fabric really close up. But. There's no sound coming from 'outside' the capsule. Ie. when I speak into it, it doesn't produce sound at all. It's really strange, because it sounds SO much like it's a working mic when I touch or move the capsule about, but nada when I don't.

So. Dead diaphragm then? :-/

Fixable in any way?
 

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