Waveform offset when mic recording

[pinned too hard in one direction]

I know how mics work and I know about vibrations. 

Oh you do, do you?

As far as mics go, if the diaphragm is pinned too hard in one direction and not allowed to freely vibrate, you can get bias. 

Okay then, explain this to me in more detail, with numbers, please... 

I'm talking about a synthesized waveform.

(Checks thread subject...)

It's just as easy for synth designers to make symetrical waveforms, so to me the asymetrical waveforms are a design flaw.

Well, maybe you could see that as a business opportunity; good luck!

As far as mics go, if the diaphragm is pinned too hard in one direction and not allowed to freely vibrate, you can get bias.  This can be from bad mic design, or from a strong puff/blast of air/wind or from both.  Just think about it and visualise it in your head.

I've been visualising it for forty years, and that's not how it's worked in any of them.

Paul

[pinned too hard in one direction]

I know how mics work and I know about vibrations. 

Oh you do, do you?

As far as mics go, if the diaphragm is pinned too hard in one direction and not allowed to freely vibrate, you can get bias. 

Okay then, explain this to me in more detail, with numbers, please... 

You are just being a pain in the ass.  I'm not going to waste my time explaining to you how a microphones work.  Do your research and study on your own. 

 

You are just being a pain in the ass.  I'm not going to waste my time explaining to you how a microphones work.  Do your research and study on your own. 

So basically, you know diddly squat. I thought so. FWIW, there's an extremely good chance that I've forgotten more about this than you know, son.

Basically, the only thing you know for sure is that you were being set up for a fall - which you would  have taken, I can assure you.

You are just being a pain in the ass.  I'm not going to waste my time explaining to you how a microphones work.  Do your research and study on your own. 

So basically, you know diddly squat. I thought so. FWIW, there's an extremely good chance that I've forgotten more about this than you know, son.

Basically, the only thing you know for sure is that you were being set up for a fall - which you would  have taken, I can assure you.

What are you talking about, Steve?  Don't act like you know anything about audio!   

What are you talking about, Steve?  Don't act like you know anything about audio!   

I did wonder whether to just post the relevant information about what happens with microphones  - some of which is so simple that even Mr Hope would perhaps understand it - simply because at least then, anybody else reading the thread would have the correct information available, as an antidote to the rubbish he writes. This is, after all, what we've done with other similar examples of this phenomenon in the past, so perhaps I will.

For instance, consider one very basic thing - some of the worst popping noises you can get from microphones come from ribbon types - where there is nothing behind the ribbon at all for it to hit, and the ribbon's only loosely suspended at the ends. And they reproduce the assymetric waveforms from voices and brass instruments very well...

The best argument though is about capacitor mics, and that one is a bit longer - I'll post it later.

Okay, let's look at the typical dimensions involved in a capacitor mic. The figures I have are for a 1/2" one, but there's not so much difference between this and a 1" one in practice. Yup, the diaphragm is very close to the backplate - about 20um is a reasonable figure here - about 1/4 the thickness of a human hair. It has to be that close, otherwise the output voltage would be very low unless a staggeringly high polarising voltage was used. If you are going to use a much higher polarising voltage, then you can afford to be a little further away, and this is desirable, because it's less likely to cause electrical breakdown. But you can't get much closer without other problems - see below.

Now let's look at typical displacements of this diaphragm relative to pressure levels. All we are really interested in is a loud sound here, so let's take a real blast of 134dB ref 20uPa - way over the threshold of pain, and around about what you might get in the way of instantaneous peaks from a puff of air. That's going to move the diaphragm about 1*10^-6m. To make this easier to understand, let's scale everything up by a million times. The distance between the diaphragm and the backplate is now 20m - a bit like crossing the road. And our almighty blast on the mic is now 1m - about a single footstep. The chances of blowing the mic diaphragm onto the backplate are pretty much non-existent, even in a mic where there was even less distance between them. And generally this isn't done, because you run into other problems to do with trapped moisture, etc, and the mic won't work properly or reliably anyway. You still won't hit the backplate though - whatever you do.

Capacitor mics are about the worst case here - a dynamic mic diaphragm moves less, because there is a much greater mass attached to it in the way of a coil, and it doesn't have anything to hit anyway, because it has to remain within the linear part of a magnetic field. That's not a problem as long as you have no magnetic conducting paths near the coil - so you keep the mountings well back from it. So there's no danger of air causing a dynamic mic coil to hit anything, in fact.

SteveG, I am not obligated to explain microphone design or anything to you.  It's not my responibility.  You have demonstrated repeatedly that you can't and don't understand me.  At least I have the decency to not stoop to personal insults like you did just because of a disagreement.  I know a lot about pro audio hardware and software, but I would rather have discussions with people who understand than with people who don't understand.  Manners are important also. 

SteveG, I am not obligated to explain microphone design or anything to you. 

That's because you couldn't.

You have demonstrated repeatedly that you can't and don't understand me. 

There's nothing to understand.

At least I have the decency to not stoop to personal insults like you did just because of a disagreement. 

Er, that was you, not me - I made an observation. You were the one doing the name-calling. And this is not about disagreeing - you are just plain wrong in your assertions about microphones.

I know a lot about pro audio hardware and software, but I would rather have discussions with people who understand than with people who don't understand. 

You don't demonstrate that you know anything at all - quite clearly, in fact.

Manners are important also. 

Shame you don't display any then, isn't it?

I'm not responsible for your ignorance, but I am responsible for making sure that it's not left unchecked. Not only that, but I'm rather well qualified to do so. If you perpetuate rubbish, then it will be refuted - just for everybody else's sake. If you don't like that, then tough - go away.