Sennheiser's MKH 8000 series goes digital

[Marco Leavitt]

Wow.

Will this make them first out of the gate with this? I know Schoeps has been working to develop similar technology. I never heard whether or not they ever unveiled a prototype.

DV - News - Sennheiser Enables Digitization of MKH Mics

[John Willett]

The first AES42 digital microphone was the Neumann D-01 Solution-D at the turn of the century. They followed that with the KM-D series which has been on the market for the last two years. Launched earlier this year was the TLM 103-D. The Schoeps CMD has been available for a while.

I did a complete piano recordining with the KM-D, written up HERE. I have a pair of KM-D with both 183-D and 131-D heads.

The Sennheiser MZD 8000 is the first one that is 2-channel; so you can put two MKH 8000 heads onto it, via a Y-cable, so you can record stereo easily into any AES3 input by using the Neumann connection kit. I will be getting one shortly to go with my MKH 8040s so I can record in stereo directly into my new Nagra VI. I am itching to get my hands on the MZD 8000!

Sennheiser first showed the MZD 8000 at the European AES in May (pdf 05 on the link) and the worlds first recording with all-digital microphones (Sennheiser and Neumann) was done in Abbey Road No.1 in July this year.

Also - Sound Devices are about to enable AES42 digital mic. inputs on the new 788T.

RME and Marian also make AES42 devices, as do Neumann with the DMI-2 and DMI-8.

The Schoeps CMD are AES42-mode1 - this means that they need to go through a sample-rate converter to clock them if you use more than one.

The Neumann and Sennheiser are AES42-mode2 - this means that they are clocked according to the AES42 protocol and don't need a sample-rate converter to operate (though they *can* also be used mode1 if they are being used with the Schoeps).

I hope this clarifies things.

[Petri Kaipiainen]

Dynamic range specs released by Sennheiser are similar to SD722, for example, so what would actually a "normal" recordist gain by using AC conversion in the mic body? Theoretically something, maybe, but anything that can be heard?

[Marco Leavitt]

Thank John. I didn't realize this technology was already on the market. I don't really understands how this works. With regular A/D conversion you generally want the hottest level you can get. With the conversion taking place in the mic body, how are the levels regulated? Is this done remotely or something?

[John Willett]

Originally Posted by Petri Kaipiainen

Dynamic range specs released by Sennheiser are similar to SD722, for example, so what would actually a "normal" recordist gain by using AC conversion in the mic body? Theoretically something, maybe, but anything that can be heard?

Yes - there are quite a few reasons for a digital mic.

having the A/D in the mic. at the earliest possible moment does away with an analogue pre-amp. and external A/D.

You never use these at their optimum as you have to allow a working headroom. Having the A/D in the mic. means that digitisation is done optimally and you get a better s/n ratio as you are losing this in the headroom you leave in the analogue signal chain.

Also - you are doing away with long analogue microphone cables that affect the high end and can pick up low level radio interference.

The AES42 spec. includes: low cut filter, pad, gain adjustment, compressor limiter, peak limiter, phase reverse, etc. all in the microphone and easily controlled from a PC or the operating firmware.

The Neumann KM-D, for example, has a 28-bit A/D and a peak limiter that prevents digital glitches due to overloading.

Yes, you can certainly hear the difference.

The only problem at the moment is that the 788T is the only portable that is having AES42 inputs and not all the AES42 spec. is supported. It only works mode1, for example, so everything has to be sample-rate converted to clock the mics.

The thing I really like about the MZD 8000 is that it is 2-channel. So a Y-cable feeding two MKH 8040, for example, to a single MZD 8000 and powered through the Neumann AES connection kit means you can feed a single stereo pair to any portable recorder with an AES3 input.

[John Willett]

Originally Posted by Marco Leavitt

Thank John. I didn't realize this technology was already on the market. I don't really understands how this works. With regular A/D conversion you generally want the hottest level you can get. With the conversion taking place in the mic body, how are the levels regulated? Is this done remotely or something?

With normal A/D you do *not* want the hottest level you can get - this went out years ago and was only applicable to early 16-bit recorders. With modern 24-bit recorders the standard is to set your 0VU point at -18dBFS - this gives you plenty of headroom for peaks - and remember a peak can be higher than the maximum digits if the sampling point is not at a waveform peak and this can cause glitches on playback, even if the meters read under 0dBFS.

If you read my report on my recording with the KM-D that I linked to above, you can see a picture of the PC control surface where you set all the levels, etc.. That was the first recording I did with the KM-D in December 2006.

In that recording I set the KM-D to +25dB gain in the mic. which was perfect for that recording. The mics. were plugged into the Neumann DMI-2 unit whic was connected to my laptop and controlled the mics. The AES3 output was fed to the digital in of my Fostex FR-2 (in the future it will be the Nagra VI now I have upgraded). I could actually have had no gain set in the mics at all, as the KM-D has 28-bit conversion, and sorted it out in the DAW (Sequoia in my case).

I hope this helps.