Sennheiser MD431 electronics repair?

[GeorgeToledo]

Fwiw, as far as related mics go; the largish looking Neumann dynamic mic uses the cartridge from a 431 as well.

 

[abbey road d enfer]

But I will also mention that just because you don’t see it on rental lists doesn’t mean that major rental companies don’t actually have it, along with plenty of other stuff that isn’t on the “for everyone” lists.

Actually I ringed the company,as an ex-shareholder and spoke to te guy who manages the inventory.

 

[abbey road d enfer]

Fwiw, as far as related mics go; the largish looking Neumann dynamic mic uses the cartridge from a 431 as well.

Yes, I saw that somewhere. I wonder if they put the same kind of EQ in it...?

 

[MicMaven]

I wouldn't say they're rolled-off, rather that they are not hyped like in an SM58.

Ah, yes. That is a useful distinction. James

 

[rock soderstrom]

Fwiw, as far as related mics go; the largish looking Neumann dynamic mic uses the cartridge from a 431 as well.

That is quite possible!

Neumann BCM-705

 

[MicMaven]

What do "computer speech recognition resellers" know about pro audio?

Ha! Your professional bias is showing! Microphones have other applications outside recording studios and stage performance!

In fact, you might be surprised at their expertise. At least a few vendors, consumers, and surely the software programmers who program recognition engines, know a little about how microphones work, and all are interested in capturing clean, accurate, articulate audio for the recognition engine to process.

JHR
__________

Sidebar - As I mentioned previously, I strongly disagree with vendors who claim the MD 431II is tantamount to the Holy Grail of speech microphones. Sheesh! Given the application, and its audio requirements, virtually any decent microphone at virtually any price will provide good results for the application. I quit working with vendors because I could not tolerate the shamefully deep levels of bushwah shoveled selling very expensive microphones to poorly informed consumers for an application that simply does not require them.

But I digress, and return the thread to its regularly schedule programming. / JHR

 

[GeorgeToledo]

Ha! Your professional bias is showing! Microphones have other applications outside recording studios and stage performance!

You might be surprised at their expertise. At least a few vendors, consumers, and surely the software programmers who program the recognition engines, know a little about how microphones work, and all are interested in capturing clean, accurate, articulate audio for the recognition engine to process. James

Coincidentally, I once programmed a speech recognition plugin which identified phonemes, and generally do a fair amount of work in audio analysis and visualization.

 

[abbey road d enfer]

Could phantom power be used to power the HPF circuit . ie from console, audio interface or other source ?

The circuit draws about 4mA, so it should be feasible.

Canford audio do a similar power unit for condenser mics , it has 4 HPF settings and 4 positions of attenuation .

Almost anything is possible. Since you DIY, you could try with a Lorlin switch and find out what are the most interesting positions.

Passive really is the way I want to go if possible , inductors suitable for low audio frequencies tend to be a bit large to fit in an xlr adapter and difficult to find ,

Small inductors exist in values up to 100mH. You would need 2 to 4 in series for achieving the desired value. The small ones that look like resistors have too high DCR; even the larger ones in 10mm format result in degraded roll-off. You need large inductors, on a decent core. I would go for an RM8 B65811J0000R030 | Ferrite pour transformateur, EPCOS, Matériau N30, AL = 5700nH, Dimensions 23.2 x 19.7 x 16.5mm | RS

they also tend to use pot cores ,

What is wrong with them?

I did a HPF for hi-z input before , 12 position rotary , just RC ,

The problem is that a simple CR filter is very dependant on the load. If you are sure to always use your box with teh same preamp, it's ok.

 

[abbey road d enfer]

Ha! Your professional bias is showing! Microphones have other applications outside recording studios and stage performance!

Yes, I should have added a smiley.

You might be surprised at their expertise. At least a few vendors, consumers, and surely the software programmers who program the recognition engines, know a little about how microphones work, and all are interested in capturing clean, accurate, articulate audio for the recognition engine to process. James

I agree, although they are not pursuing the same goal as most of us. We are generally looking for a pleasing result, without second thought about measurements. And it's all right. In our case, measurements are justified as a way to try to establish a lnk between perception and science; not everybody has to do it.
For people who deal with other applications, it is often quite different. Anyone who works in speech recognition, or acoustic surveillance (like that used in nuclear plants) has the duty of supporting their choices and decisions on hard facts. Not so much for us in music applications.
I have some professional experience with the automobile industry and I found myself a few times in disagreement with their methods. For example they evaluate the quality of the sound of doors closing (a very important sales motivation) with headphones. I think it disconnects from a large part of the sensation produced by the impact of sound on the chest and pupils. They thought I was just trying to sell them speakers!

 

[abbey road d enfer]

Sidebar - As I mentioned previously, I strongly disagree with vendors who claim the MD 431II is tantamount to the Holy Grail of speech microphones. Sheesh! Given the application, and its audio requirements, virtually any decent microphone at virtually any price will provide good results for the application. I quit working with vendors because I could not tolerate the shamefully deep levels of bushwah shoveled selling very expensive microphones to poorly informed consumers for an application that simply does not require them.

Being privvy to some fairly advanced developments in the domain of teleconferencing, I know that microphones are not a subject anymore. I believe there is no discussion in this domain, with MEMS having taken over the market. Frequency response and directivity are DSP-coded. Focus is on echo elimination and diffuse noise reduction. These are things that, ATM, are not compatible with music recording/diffusion, but who knows? Who would have thought 20 years ago that the unwanted artefacts of Autotune would become an almost requisite in today's production?

 

[MicMaven]

Yes, I should have added a smiley.

No worries - your message came off all in good humor. You rarely leave yourself open to a poke in the snoot!

We are generally looking for a pleasing result, without second thought about measurements.
For people who deal with other applications, it is often quite different.

Quite right. It is horses for courses. Different strokes, and all that jazz.

I have some professional experience with the automobile industry ... evaluate the quality of the sound of doors closing with headphones. I think it disconnects from a large part of the sensation produced by the impact of sound on the chest and pupils. They thought I was just trying to sell them speakers!

Quite right, again. Another case of engineers at odds with the Marketing Department. I have friends who are auto design engineers, and they constantly bump heads with the Marketing guys - you KNOW how that goes! According to the Talking Heads, "Same as it ever was, same as it ever was ..."

It's all good. By the way - have we determined whether the MD 431 is, in fact, dull, or can the examples under discussion be improved?

Happy trails. // James

 

[Whoops]

"nearly absent of riders and rental mic lockers"

I confirm that it's absent from present day Artists/Bands Riders.
And most modern PA companies don't even have one in their stock

I know 2 main artists in Portugal, where they use the MD431 as the Lead vocals microphone, but those acts bring their own mics with them (main mic + spare)

It is probably the best dynamic live microphone for vocal tasks.
A fantastic microphone, everyone should try it.

I also agree, it's a tremendously good Microphone, I love it.
I guess it was just forgot over the years because new models from many different brands appeared.

And also Sennheiser has their new line of Live Vocal mics (e945, e935, e835)
and also wanted to concentrate marketing on the newer mics, which are pretty good also.

The switch on it seems to be a significant deterrent.

The On/Off switch it's just completely stupid,
it makes no sense in a Live Sound situation to have a switch that can be turned off by mistake or fail in the middle of the show.
At least they could do 2 versions, with and without the switch like Shure does.

I was not too surprised by this bad decision from Sennheiser, the MD421 although an amazing microphone has the worst clip ever made in any microphone, it's the weak point since the microphone was released many years ago, and even thought Sennheiser made many revisions and changes to the 421 model, including completely new capsules, they never changed the horrible Clip design.


It's very Curious that I saw this thread now as 5 minutes ago i was seeing some performance from Nirvana and noticed Kurt Cobain was using the MD431 back in 93/94

 

[Rossi]

At least they could do 2 versions, with and without the switch like Shure does.

I don't know about the current MK II version, but with the old version you could simply take off the switch. There's no hole under the switch and no cabeling. The "switch" is just a slider with a magnet that activates the reed relais inside.

 

[Rossi]

The main reasons for passive EQ are:

• presenting a flat-ish frequency response, which however is not a guarantee of a good sounding mic
• making the mic "sounding good", but one's good sound is another's cacophony
• correctly a blatant defect, which should be adressed by redesigning the mic

The Sennheiser MD431 looks to me like something that could only come from teutonic engineers,

Maybe it's my teutonic soul, but I really like the MD 431. I own an old one that I bought on a fleamarket, and until now I didn't even know it has a passive filter inside.

I quite like passive filters in dynamic microphones; I even designed one for the SM57 and SM58 that flattens the presence peak. I think it sounds much better that way. The LCR filter is in parallel with the voice coil, so also adds some electrical damping. That's something you can't do with an external active EQ. I also think a passive filter inside the mic can make it more versatile and easier to handle.

It's easier to work from a largely flat response than adjusting an crooked response. The presence peak in a SM58 may suit many voices, but if you need something different, it's difficult dial in the precise setting that will flatten the response. With a largely even response, it's quite easy to dial in a presence boost, if needed, that best suits that particular voice. It's no longer one-size-fits-all. But I'm German, so YMMV.

 

[raketenmann]

I wouldn't say they're rolled-off, rather that they are not hyped like in an SM58.

Which are all known to hype the presence range, so what you perceive as a lack of HF is probably a lack of presence.
View attachment 112945View attachment 112948View attachment 112949View attachment 112950
In comparison, teh MD431 may seem to lackappeal.
View attachment 112951

Thx. I did have all these fr-curves in mind. But I would say compared to the PR20 the fr-curve is not so far off, but the sound was still drastically off.... And one of the two of the mics were even more!

But since I don't understand much about electronics: does someone of you have a clue if in the circuit design of the MD431 is some sort of component that could be responsible for a loss in high frequency content. And probably I am wrong in calling it highs or treble, I am talking about the high mids also...

 

[MediaWorksOKC]

Would the aging tantalums not contribute to a "dull" sound over time?

 

[Whoops]

I don't know if the Tantalum caps could be the culprits, but it's just 4 of them so changing them is easy and quick. No big deal, you can do it anyway

But if there's really high end loss I think the problem is in the capsule itself and not in the passive circuitry after it.
Having a known good 431 microphone to compare that one with would reveal if there's really high end loss or not and what amount of loss

 

[MicMaven]

Having a known good 431 microphone to compare that one with would reveal if there's really high end loss or not and what amount of loss

Friendly half-serious theoretical comment / question =

So ... in the spirit of having two watches means one never knows what time it really is ... then ... um ... ahem ... how do we know what "known good" sounds like? I mean it sort of begs the question as to which IS the good one? Is it the one under scrutiny in this thread or the other one used as for comparison as an ersatz control group. How do we know the second, "control group" example is how it is supposed to sound? Should we not ask Sennheiser to comment on which one sounds right? Should we test several other examples to seek a consensus or average? The basis of the inquiry is to determine if his 431 sounds right, ... right? Perhaps the one under scrutiny is the very model of a perfect model 431, and the control group are all off the mark?

I am NOT trolling for an argument, just asking a question about proper test protocol. If we are unsure whether the first one is off its feed, then how do we know a good one from a bad one? What IS the correct sound profile?

Hoping this makes sense! James

(Posted in good humor and with good intentions, although my road to Heck is well paved with all of my good intentions!)

 

[Whoops]

I understand what you say, but I as a sound engineer I also understand what I said by "known good mic".
It could be a new or almost new 431 microphone, it could be a 431 that although older was never on the road and never got that much use, or a 431 that sounds very good in your opinion so you don't have any reason to suspect it's not up to specs... there's many more
So addressing your question of course by a "known good" mic you need to have a reason to trust it's a good item to do the comparison with.

I have many 421 and 521 microphones, of many ages and revisions, some of them had a lot of use already and others had capsule repair service at some point.
So some months ago in order to really know what I had in terms of performance for each of them I compared my 6 mics against a completely new 421 and also an older 421 from a studio that I used many times in the past and that I love it's sound.
I was not looking for slightly/marginal differences in sound, I don't care at all for that, I was looking to more extreme things like Low end Loss, High End Loss, Distortion, rattles, strange and pronounced frequency peaks out of the average of the 2 reference mics. That was the goal.
I tested with 3 methods, all recorded in a DAW:
1) my Voice, at the same distance with the same vocal sounds
2) recording Tom hits, and recording a guitar amp with overdrive sound
3) in front of a full rage speaker playing Pink Noise, all at the same distance, and measuring frequency response with Smaart so I could save each response Graph and compare the graphs of each of the mics.

The 2 reference microphones were similar in Low End and high end, and the graphs showed very similar frequency responses.
All my mics that had responses similar to those 2 were marked good.
1 of them had -3dbs starting at 200hz and the LF rool off was at 80hz, so that one had Low End Loss by the audible tests and also very clear on the frequency response graph.
Another one had a strange very pronounced 5Khz peak 6dbs above all the other graphs, and the rest of the range also many peaks and dips compared to the 2 reference mics and also all the other ones, it was completely off the average, so that not only sounded very strange and you could also see in the graph that it was way off.
So I concluded this 2 mics were bad and unusable for my personal needs.
I trust very much my listening judgement but I also like to see the confirmation of my hearing conclusions on a measurement device.
I'm a very practical and pragmatic person and Engineer, this is enough for me to make my decisions.

Hope this helps MicMaven

 

[Tubetec]

Hi Whoopsy ,
If those two mics broken mics need a new home I'd be happy to take them for experimentation .