Topic: KM 184 D- Story?

[Mr.Fantasy]

What is the deal here...?

You only need the one microphone?

Some sort of a control computer?

Will a someone please explain this to me...?

Here is the link to Neumann about it...

http://tinyurl.com/36x66e

But can someone explain how this differs from the regular 184's? Besides obviously having this Digital label....

[F.O.Bean]

well, you can forgo the dmi2 controller and get them with SPDI/F or AES/EBU outputs directly. or you can run them into the controller box they have. you can get cards/hypers/omnis just like the normal KM18x. they have a LD that has I believe 9 selectable patterns with the dmi2 controller box

they look sweet, but 2 x LD's are 17k with the dmi2 box....

[Mr.Fantasy]

You like Large diameter more than small?

[edit:no this is not a setup for a "bigger is better" joke]

[F.O.Bean]

You like Large diameter more than small?

[edit:no this is not a setup for a "bigger is better" joke]

I prefer SD's, but I will def have some 414's one day

[DSatz]

Mr. Fantasy, the main difference between the KM 184 D and the regular KM 184 of course is that the "D" model has its own A/D converter and clock built in. Plus the capsules are interchangeable with the others of this series, which isn't the case with the analog KM 180 series.

If you are going to use two or more microphones of this type simultaneously, some piece of gear has to convert their signals to the timebase of a common clock, since by default each microphone runs on its own. Neumann makes a two-input device which--it's been a while since I read up on it and I'm not completely sure any more--but I think it may actually send its own clock signal to both microphones rather than reclocking their signals.

At any rate you would need something like that in order to make stereo recordings. The relatively low-cost battery or AC powering devices which Neumann sells for this series have S/P-DIF or AES/EBU outputs, but they handle only one microphone each. They don't interconnect in any way to generate a combined bitstream from two microphones--which again would require coordinating their signal clocks, or else syncing to an external clock input.

--best regards

[Mr.Fantasy]

I am not looking at buying any....far too expensive for me...

I was just wondering...I guess I have never seen a mic with its own a/d before....

[John Willett]

I have a pair of the KM 183-D (omnis) and also a pair of the KK 131-D (flat omni) capsules.

The capsule sound of the Km 184-D is the same as the analogue KM 184 - BUT - the KM-D series have a 28-Bit (NB: 28 *not* 24) ADC inside the microphone body.  Because the A/D is done at the microphone capsule you do not need a microphone pre-amplifier; also you do not need to allow for the headroom in your external A/D - this gives you an improvement of about 30dB in signal / noise ratio.  They are *quiet*.

As you don't need a mic. pre. and ADC the mics actually work out rather cheap.

But you *do* need the DMI-2 if you run more than one mic.  If you run more than two, you will either need several DMI-2s or the new RME interface which takes 8 microphones.

*Very* nice mics.

[DSatz]

John, the capsule and the first analog stage are essentially the same as in the analog KM 184, no?

Since those two things are the main noise sources in any condenser microphone, and since in the analog KM 184 they combine to create a 22 dB SPL equivalent noise floor (CCIR), it is difficult to see how any A/D converter could reduce this noise level by 30 dB, since that noise is permanently a part of the signal which is fed to the converter.

Given these facts, if it were in fact possible to reduce the noise by 30 dB in the digital version then logically, it should be possible to reduce the analog KM 184's noise level by 30 dB as well. However, this is clearly not the case. So something is very wrong with this 30 dB figure.

Or perhaps the problem is with the way this figure is being used. It seems to describe the maximum theoretical dynamic range of the binary data stream, rather than saying anything about the dynamic range of an actual microphone which produces that data stream. But say I estimate your height to be 6 feet, 1 inch--it doesn't make my guess any more accurate if I write that as 73.000000000 inches; it's still just an estimate. Those extra zeroes are just "marketing bits."

--best regards

[John Willett]

John, the capsule and the first analog stage are essentially the same as in the analog KM 184, no?

As far as I am aware there is just the capsule and an fet before the A/D.

The 30dB figure comes from the fact that with a normal system you use an analogue pre-amplifier that has to be set to allow enough headroom before distortion - then - in an external A/D you have to allow further headroom to avoid distortion.

Putting the 28-bit A/D right by the capsule means that you don't have these reductions because of headroom resulting in a 25 to 30dB better figure.

This I got from a PowerPoint presentation from Neumann Germany.

I hope this makes sense.

[jnorman34]

hmmm - could someone please explain how you use two of these mics at once with the adapter?  i read the material on the neumann site, but it was not clear - it says you can cascade more than one, but isnt clear on how.  also, most laptops do not have AES/SPDIF - they have USB2 and/or firewire.  how exactly does this system get connected to a normal laptop?  danke.

[Mr.Fantasy]

John, the capsule and the first analog stage are essentially the same as in the analog KM 184, no?

As far as I am aware there is just the capsule and an fet before the A/D.

The 30dB figure comes from the fact that with a normal system you use an analogue pre-amplifier that has to be set to allow enough headroom before distortion - then - in an external A/D you have to allow further headroom to avoid distortion.

Putting the 28-bit A/D right by the capsule means that you don't have these reductions because of headroom resulting in a 25 to 30dB better figure.

This I got from a PowerPoint presentation from Neumann Germany.

I hope this makes sense.

Wow I don't recall ever seeing anyone disagree with DSatz...I just take his posts as universal truths and move on...

Just kidding...DSatz gets a +T anytime I see one of his posts (even though I don't read them all) due to how much his posts have helped me...

Actually I have probably been doing comparable amounts of +T...ing...as reading posts....

Oh well...

[John Willett]

hmmm - could someone please explain how you use two of these mics at once with the adapter?

Two plug into the DMI-2 and the output is AES-3 at 24 bit.

i read the material on the neumann site, but it was not clear - it says you can cascade more than one, but isn't clear on how.

Very simple - just set different id numbers to the DMI-2s and have multiple AES-3 outputs.

also, most laptops do not have AES/SPDIF - they have USB2 and/or firewire.  how exactly does this system get connected to a normal laptop?

This is professional equipment - if you want to connect to a laptop you need a sound card (eg: RME Fireface, etc).  But if you want more than two the RME AES42 8-channel unit may be the better buy.

[Mr.Fantasy]

These mics look super sweet...and if I had any money (that sort of money)...I would try these in a heartbeat...

So what is the highest bit rate there is?

I have seen 32 bit-float...on Audacity, can you record at 32 bit, or higher?

[John Willett]

Wow I don't recall ever seeing anyone disagree with DSatz...I just take his posts as universal truths and move on...

I'm not disagreeing, just explaining.

It's not the A/D  on its own that gives the better noise figures, but the fact that you now do not have to allow all the headroom in external equipment that would have reduced it.

[John Willett]

These mics look super sweet...and if I had any money (that sort of money)...I would try these in a heartbeat...

So what is the highest bit rate there is?

Normally 24-bit is the recording standard.

Neumann get 28-bits by a patented method of using two 24-bit converters in a special way to eliminate the crossover distortion that you normally get using two converters - I think you can download the details as a pdf from the Neumann website.

And don't forget that Sennheiser will also have an AES42 unit to compliment the new MKH 8000 series very soon.....