Topic: KM 184 D- Story?

[Mr.Fantasy]

If I may ask DSatz, are you homegrown smart or do you have a degree in something? What kind of degrees are there that would benefit recording I wonder...

[John Willett]

If you do contact Mr. Peus please give him my very best regards; I don't know him at all well but we are on an AES standards committee together, and he seems to be a very nice and very honorable human being.

Yes he is - I have just sent him an e-mail and pointed him to this thread to give his input, or to let me know how to put it (or put me right if I have got it wrong - though I hope not).

I know how I understand these things (if I got it right) but am not sure how best to put it.  I am a classical music recordist and technical support, but I am not a microphone designer.

[DSatz]

Well, to summarize all my previous blather in two sentences, it seems to me that this graph shows a range of possible outcomes, from the theoretical best case to something approaching a nightmare scenario. But I think that the majority of the signal quality loss in this picture should have been avoidable--if not, I don't see why not.

As a comparison: I have a Grace Lunatec V3, a combination mike preamp and A/D converter which is fairly well known around here. It has what I consider to be a rather good mike preamp. But if that were not the case--if the preamp stage was noisy and had high distortion--there is no way that the converter could make up for this. The close integration of the two units would no longer be any virtue in that event.

I'm just saying that it's the same with "digital microphones" which are, of course, just analog microphones with abbreviated analog circuitry and built-in A/D converters. They have a certain noise level which comes from the capsule and the FET; the integration of a converter, no matter how many bits it uses, cannot take that noise away. Nor can it raise the overload point of the FET. So the idea of a digital microphone being 30 dB quieter than its analog counterpart struck me immediately as impossible.

--best regards

[John Willett]

I have just been having an interesting chat with Stephan Peus, who sends you (DSatz) his regards.

He says that, in theory you are correct - but - not in practice.

In practice you do not know what is going to happen next and you have to allow headroom in the microphone pre-amplifier and the ADC to account for these unknowns.

What you are doing is not gaining extra s/n, but not reducing the theoretical s/n as you have to do with an analogue microphone.  The mic. pre. will add noise, and will be working below the theoretical figure as you have to allow headroom for unexpected peaks etc.. The ADC will not be working at the theoretical figure as you, again, have to allow for these unexpected peaks.

With the digital mics, you do not have to do this and can use all the dynamic range of the microphone.

This is where the gain occurs.

I hope this is clear - if not, please give Stephan a ring at Neumann who will make it clear to you (he is a nice helpful chap).

If you only look at the theoretical, you are correct - in the real world you get the gains because you have to allow headroom for the unexpected.

Phew!