Microphone Sennheiser MKE 40 R

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Re: Microphone Sennheiser MKE 40 R

Post by Admin on Mon Mar 20, 2017 5:20 pm

Hello again Ruud,
Thank you for letting me know. I am so glad they arrived in good time. Just a couple of working days. Mail to Spain usually takes only a couple of working weeks.

I have not taken my mics apart, but I was expecting to find a LOT more inside them, especially if you consider the price of them!! So it is just an ordinary, bog-standard, electret condenser microphone. Maybe a good quality insert, but still nothing special.

I shall follow your lead and fit a new cable, and thank you very much for sharing your information with us. It is really appreciated. Especially the photographs. I will be interested in hearing how you find them in actual use. I rather prefer real crisp, full-bodied audio.

In the Multimedia Studios we bought a few Sennheiser "professional" radio mics. They had a small mic that was fixed to clothing using a crocodile clip, but I found that they took the top off the audio. On the spectral display, everything above about 8kHz dissapeared. "Naked" condenser microphones can often go up to ultrasonic frequencies.

Ok Ruud, now I have to go. Maj-lis arrived yesterday afternoon and will be here for about a month, then I will be in Spain for a month. I hope to have some time on the hobby, but Maj-Lis is just so please to see me now that I have to give her some time to catch up.

Very best regards and many thanks for posting the photographs. That has helped a LOT.
/Harry - SM0VPO

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Re: Microphone Sennheiser MKE 40 R

Post by Ruud on Fri Mar 17, 2017 3:54 pm

Hi Harry,

The microphone arrived here today. Many thanks for that!
In the meantime I have done some 'surgery', because I would like to add a decent length of microphone cable to the microphone. 
At the back of the microphone, there is a screw, probably hidden under a piece of plastic. (Or whatever...) 
When you remove the screw, you can take out the front piece of the microphone.
Inside that front piece, there is a threaded ring.
If you unscrew the ring, the internals of the microphone become visible.
Take care to keep all parts in the correct order!
Finally you will see the little capsule itself, with a bit of 'micro surgery' it is possible to solder a new (longer) cable to the microphone!
I hope this information is useful for you.

Many thanks again and this weekend I will try how the microphone sounds!


New cable added:



Last edited by Ruud on Sat Mar 18, 2017 9:56 am; edited 1 time in total (Reason for editing : Picture added)
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Re: Microphone Sennheiser MKE 40 R

Post by Admin on Fri Mar 17, 2017 7:05 am

Hi Ruud,
Little info, I took your advice and bought a cheap USB sound card. Adobé Premiere and Audition cannot find it, so I had to disable the internal sound card, then it burst into life :-)

I captured the video as per normal through the firewire, and I also recorded the sound on the same machine using my nice directional mic: lovely full-bodied sound and no echo's from the room. Worked a treat. Thank you very much. I have been playing about with the audio for a while, but I should have given up on the PC audio a long, long time ago.

http://www.bhphotovideo.com/images/images2500x2500/polsen_scl_1075_cam_mnt_condensor_shotgun_984901.jpg

It is interesting that I worked for 10 years using a custom-built sound studio, with sound absorbent foam, RF screening, etc. But a simple directional microphone at 1 metre can give just as good audio and remove reflections form the room. One of our customers kept asking me to process their sound, and they used to use a laptop in a stationary car: really quiet and the shape of the saloon/upholstery avoided reflections. Where there's a will, there's a way :-)

All I need to do now is to film all the clips and I can get the video finished and post it on the homepages. Thank you for the advice.

Have a nice day, and very best regards from Harry - SM0VPO


Last edited by Admin on Fri Mar 17, 2017 7:30 am; edited 2 times in total (Reason for editing : corrections to grammer + added picture)

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Re: Microphone Sennheiser MKE 40 R

Post by Ruud on Tue Mar 14, 2017 8:08 am

Yes, I know the crackling noise when you move a microphone cable.
The higher the impedance, the louder the crackling!
I can even hear it when using a 2 K.ohms input impedance microphone channel.
Some cables 'crackle' more than others, but I always wondered what was causing this sound.
If there is any voltage on the cable, I could imagine that you would get the same effect as a condenser microphone. (Q = C * U) So if the capacity changes, the voltage will also change.
But even on non-phantom powered microphone cables I get this effect!

Take care that crystal microphones need a very high input impedance, usually 1 Meg. or even more. (This is also needed for piëzo guitar elements etc.) Crystal microphones produce a strong signal, but most of the time the audio quality is less than perfect. 
Use a good quality (low capacity) cable, because the cable capacity together with the high impedance will create a low-pass filter! Also don't make the cable longer than needed, for the same reason.

By the way: nice videos! (You are a good teacher!)
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Cable microphony?

Post by Admin on Mon Mar 13, 2017 10:12 pm

Hello again Ruud,
I received your e-mail, and replied to it.

One other small question, I know that you have a lot of studio experience:
I connected an old crystal mic into an AF amplifier. Do you remember those crystal dynamic microphones? I salvaged a 5m length of cheap audio coax but I had to throw it away.

If I wiggled the cable or dropped it on the floor then there were loads of crackling noises, like someone rustling paper. I even disconnected the mic and it was exacly the same. The audio level was really high.

Have you ever experienced anything like this?

I presume it was due to the high impedance of the amplifier and microphone. I never considered using the cable with a low impedance mic, I just threw the cable away in disgust. I wish now I have done a few more tests with it, just for basic knowledge.

I worked in the Ericsson multimedia studio, mainly using my voice in 750 video films. I edited all the audio files, but I never experienced microphonic cable before. If you are interested in seeing any of the films then here are a couple of links (the third one is a funny one :-)

How to put on the plug for beginners
https://www.youtube.com/watch?v=m5H8-kQ0er8&index=13&list=PLOpvBJnYozzxi4BAhgOqLKB4ICpQQVDqj

Mini-Link alignment
https://www.youtube.com/watch?v=JzNO_JHC5vM&list=PLOpvBJnYozzxi4BAhgOqLKB4ICpQQVDqj&index=15

Comedy
https://www.youtube.com/watch?v=jGOp5BJIxoI

Anyway, please let me know when you have received the microphone. I would be interested in hearing your thoughts about the unit. I may "butcher" my Camcorder and put a 3.5mm jack on it so I can have an external microphone, and these MKE 40 R mics could be perfect for the job.

Best regards from Harry - SM0VPO

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Re: Microphone Sennheiser MKE 40 R

Post by Admin on Mon Mar 13, 2017 8:04 pm

Hi Ruud,
Yes, absolutely, but I wonder if there is something about these being body-worn in a studio?
These things were clipped onto peoples clothes, jammed in place by a magnet inside the clothes.

But I am really happy with the microphones. I have three of them, so if you wnt one then you are more than welcome to one?

Best regards from Harry

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Re: Microphone Sennheiser MKE 40 R

Post by Ruud on Mon Mar 13, 2017 6:49 pm

I don't think earth loops are very realistic here.
This would only be the case if both the microphone side and the connector side would be connected to an earth node with a different potential.
But the microphone side is usually free from earth.
(In studio situations earth loops between equipment can be a real nightmare!)
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Re: Microphone Sennheiser MKE 40 R

Post by Admin on Mon Mar 13, 2017 5:06 pm

Hi Ruud,
I understand the screening process they have used. I suppose it is also to prevent earth-loops. But it is obvious that the microphone is a very basic unit, with just the customary in-built FET. buffer.

As regards the computer audio, I have an audio/video capture dongle that I may give a try. Thanks for the idea. I never thought of that. I am aware that many computers have "issues" with the internal microphone. My new Asus does not recognise the internal microphone, or more to the point, it sees it but I cannot connect anything to it, other than Skype, and the audio is far to low to be useful. It also has a single 3.5mm jack that can be configured for mic/headphone/speaker, but not all at the same time.

My HP WinXP machine is a lot better, but the external MIC sounds terrible.

Many thanks for the info. BR Harry

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Re: Microphone Sennheiser MKE 40 R

Post by Ruud on Mon Mar 13, 2017 9:29 am

I noticed that Sennheiser did this more often.
The 'screen' is only 'the screen' (Faraday cage) and is not connected to the electronics.
I suppose the idea behind this is that disturbing fields influence both conductors inside the shield with the same amplitude, thus cancelling each other.
Most other electret microphones usually use the screen as 'ground'.
But this means you have to use an external resistor (in your case the 10K) to get audio.

Concerning your computer audio: most of the time a simple USB audio interface will improve the audio quality significantly. (You are more 'isolated' from all internal power voltage pollution, such as the harddrive motor etc.)
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Re: Microphone Sennheiser MKE 40 R

Post by Admin on Sun Mar 12, 2017 9:16 pm

The "1 volt" is a real guestimate.

My little china-scope does not like DC and on the 1V range, if you exceed 1V it affects the second trace. It could be anything, but I do know that the peaks are more than 100mV, possibly 1V peak when I "oooaarrr" directly into it (between 30mV and 300mV RMS) (primary trace off-screen, secondary trace reacting to overload).

The guy I got them from said that they are very sensitive, and that is confirmed. I was more than a little surprised that the mic element is not connected to the shield as a return. But this is great, I can use them.

Coincidentally I am at present making a video and the sound from my camcorder is diabolical (no AF input). I have a directional stick mic, but the output recorded via the computer MIC port is really crappy - sounds like loads of reflections in the room. I suspect the mic is connected between the two channels, which will give a cancellation and a load of low-level stuff. If I connect the stick-MIC to a pair of active headphones then I hear lovely, full-bodied audio without an amplifier.

So I need to somehow get decent audio into the computer. Probably record it using Audition on the other computer and replace the soundtrack in the video.

Also, Maj-Lis is coming back to Sweden next week, so I have to clean up the apartment. She wants a home, not a workshop Crying or Very sad 
Hope you have a good night.
BR Harry


Last edited by Admin on Sun Mar 12, 2017 9:19 pm; edited 1 time in total (Reason for editing : seemed like a good idea at the time.)

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Re: Microphone Sennheiser MKE 40 R

Post by Ruud on Sun Mar 12, 2017 7:01 pm

Wow, 1 volt of audio from a microphone is a *lot*!
But good to read that you've got it working!
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Re: Microphone Sennheiser MKE 40 R

Post by Admin on Sun Mar 12, 2017 5:37 pm

Hi Ruud,
The microphones work perfectly. The cable shield is only a screen.

I connected 9V to the RED and BLUE through a 10K resistor and I have, like 1V of audio when I speak close to the mic. It is a bit difficult to judge because my scope is a little iPhone-sized unit, battery operated, made in China, and the DC offset is a problem.

But I do have audio out of them and they work fine.

BR Harry

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Re: Microphone Sennheiser MKE 40 R

Post by Admin on Wed Mar 08, 2017 9:12 pm

Hi Ruud,
That was an interesting and quite artistic link. Just shows what you can do with an oscilloscope. About 20 years ago I made an impossible waveform generator where the waveform doubled back on itself, seemingly going back in time. Viewed on a regular oscilloscope. I did it by using data stored in an EPROM and the values were top, middle, bottom - shift by 1 then repeat. The scope smoothed them out and you saw three sloping lines, each one begining before the previous slope had ended.

The video I saw was porported to be more sinister, with hidden messages. I cannot find the page now, but it was something along the lines of this video:
http://metro.co.uk/2015/10/20/can-you-solve-the-riddle-behind-this-truly-scary-video-5450369/
The message was 666 repeatedly and a devil-like image on the Audition-like spectrograph display. The sound (all below 1.2kHz) was some satanic sounding rubbish.

Here is a typical image that I am talking about:


I have been using Audition since about 2004, but I also find SoundForge has some decent editing functions, and filters. I like Audition most, especially as I can be link a sound track to my PropellorHead "Reason" synthesiser app (yes, I still use MIDI :-). I mainly create backing tracks to accompany myself on the piano accordeon. I don't need a workbench for the accordeon.

Ok, getting late and I gotta get up in the morning.
Goodnight and thanks for the link. I thought it was really clever.

BR Harry - SM0VPO

(PS - I don't sing! Embarassed )


Last edited by Admin on Wed Mar 08, 2017 9:31 pm; edited 1 time in total (Reason for editing : Image added)

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Re: Microphone Sennheiser MKE 40 R

Post by Ruud on Wed Mar 08, 2017 5:35 pm

I suppose you were referring to "Oscilloscope Music" by Jerobeam Fenderson?
https://www.youtube.com/watch?v=qnL40CbuodU
Impressive!!! (I like the 'bicycle'!)
And yes, I do know Adobe Audition (the successor of Cool Edit Pro).
I still use it next to Steinbergs WaveLab and a couple of other audio programs in my studio.
For multitrack recording I use Reaper. It's free for private use, but a license is not very expensive. I can record 32 tracks, 24 bit, 48 KHz without any problem.

Curious to know the result of the microphone experiment!!!
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Re: Microphone Sennheiser MKE 40 R

Post by Admin on Wed Mar 08, 2017 5:01 pm

Hi again Ruud,
I understand perfectly. So there is likely to be nothing special in these beasties, other than quality and sensitivity. But thank you very much for the pictures.

I have never dismantled a condenser microphones so I didn't know what they looked like on the inside. That must have been a monster mic you took apart to be big enough for a PCB. I will probably fire one of them up this evening. If the oputut is then I may be able to have SKYPE on my laptop computer Very Happy   I have an ASUS laptop, with SSD, bells, whistles, hooters and all manner of extra bit thrown in, but SKYP app cannot do anything with the microphone. I have to really shout at the computer.

I do have a lovely pair of $2000 studio speakers and so I have a lot of fun with sound.

While we are on the subject of sound, have you ever seen Adobe Audition? I love it, and especially the spectral display of a sound file. I have a file published on the net that sounds very WeIrD and when you view the spectral display you see a picture. It must have taken someone loads of time to work that one out.

Anyway, thanks for the advice I will have a go at the microphone as soon as I have finisged my dinner.

Have a nice evening and very best regards from Harry - SM0VPO

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Re: Microphone Sennheiser MKE 40 R

Post by Ruud on Mon Mar 06, 2017 10:00 pm

Usually those electret microphones consist of the electret capsule itself, a FET and a resistor.
The FET is most of the time used as a source follower.
The electret capsule is connected between the gate of the FET and ground.
In those microphones, they use a special type of FET, with a little 'gate leak current', caused by a (non-conducting) internal diode, to bias the FET.
In most cases the screen of the cable is 'ground' (negative), one wire is connected to the drain of the FET (positive supply voltage) and the other wire to the junction of the source of the FET and the source resistor.
So if you use the 'wrong' connection, you will apply a voltage over the source resistor in the microphone, while the drain of the FET has no DC.
Not very much can happen! (As long as the current is not too high.)
I noticed that those electret microphones even work on the current of my multimeter in the 'ohms' position! My multimeter generates different currents in the Ohms x 1K, Ohms x 100 and Ohms x 10 ranges. (Ohms x 1 K gives the lowest current).
Take care that there is DC on the output, so use a capacitor between the wire of the microphone an the next amplifier stage.
Here's what is in a generic electret microphone:

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Re: Microphone Sennheiser MKE 40 R

Post by Admin on Mon Mar 06, 2017 9:25 pm

Hello Ruud,
Many thanks for the info. 15 years ago I would have done something like that without thinking, but I have learned the hard way that the more expensive gear can be a lot more complex and fragile. They often use a different technology the more advance (and expensive) the stuff is. I once managed to blow up a miniature industrial processor board that stored video in non-volatile RAM instead of an HD. I didn't know it was a positive Earth, and there were no electrolytics on the board to indicate polarity. All SMD stuff with unknown numbers.

But I will give it a try exactly as you say: you have a lot of experience of microphones. I have three of them and I know that they are ultra-sensitive so I was a little unsure if there was anything "special" in there. As you say, a couple of mA is unlikely to damage anything, unless I am VERY unlucky. I will let you know what happens, sound or smoke.

If you are interested, I bought a directional microphone (from China, and surprised about the excellent sound and narrow beam). I can make videos and exclude a lot of background noise, just me speaking. About a month ago I bolted it to the focus of a parabolic reflector, and the result was almost unbelievable. I pointed it at people in the Willy:s car park, about 100 metres distant. Quite difficult to hold steady but I could hear every word, providing the speaker was speaking in my direction. I thought that sort of directional property was limited to 007 movies!

Ok, Ruud. Thank you very much for the information. I will give it a try. I have three of them, and if it works then you are welcome to one of them? (I only need two). The lapel mount magnets are missing, as well as the wind covers, but that should not be much of a problem. They were used in Swedens TV4 broadcasting studios. They changed some of the equipment and these were consigned to the waste bin.

Very best regards from Harry - SM0VPO


Last edited by Admin on Mon Mar 06, 2017 9:33 pm; edited 1 time in total (Reason for editing : Couple of spolling mistakes.)

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Re: Microphone Sennheiser MKE 40 R

Post by Ruud on Mon Mar 06, 2017 8:06 pm

About the Sennheiser MKE 40 R: I would apply the supply voltage through a (~1K) resistor.
If it works, remove the resistor, if it doesn't, swap the wires and try again.
The current through the resistor is so low that it is unlikely to cause any damage when the connection is incorrect.
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Microphone Sennheiser MKE 40 R

Post by Admin on Sun Feb 19, 2017 6:32 pm

Hi again,
Does anyone know anything about the Sennheiser MKE 40 R microphone?

I am lucky enough to "aquire" three of them, but the cables have been cut off. I just have the mic without the magnet and without the cover. I have the user datasheet but there is nothing about the connections. The 6cm stump cable I have has a braid/shield, one RED and one GREEN wire.

I asssume it is a bog-standard Electret mic and that I can simply stuff 5 volts or so between the RED wire and braid, and get audio out of the green. In view of the quality of these items, I am a bit reluctant to do that without first finding out for sure. If they have built something different in there then it could be damaged.

If anyone KNOWS about these thingies then I would be grateful for the "thumbs-up" before I simply connect power to them.

<------------------------>

I have managed to aquire a pair of Sony FCB-IX10P CCD cameras modules. These devices are often used in photo-booths and have even been used in speed-cameras. My two came from Swedish police cars. Controlled by RS-232. Fantastic clarity, and have Karl Zeis optical zoom lenses :-)

It is amazing what you can find car boot sales offered as "scrap" electronics.

I was hoping to rip out the internal Electret mic and use a socket to feed the Sennheiser MKE 40 R in. The internal mic is ok, but not too sensitive, and for surveillance cameras at home (in Spain) it would be better to place the microphone somewhere closer to the centre of the observation area.

That's why I need to know more about the Sennheiser. It is not very often you get the opportunity for such good quality stuff so I wanted to check before I start "fiddling".

Best regards from Harry - SM0VPO

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