Review: Neumann KM184D
This digital ‘pencil’ boasts Neumann’s signature sound, while opening the door to an entirely new approach to sound capture.
By Brad Watts
26 October 2007
Once in a blue moon a microphone gets brandished in my direction for review. It’s a rare occurrence, mostly because Andy snaffles them first. So, in an effort to make amends for his compulsive microphone hoarding, our illustrious editor has sent me Neumann’s latest expedition into digital microphones, the KM184D. Neumann has been down this road in the past, of course, with a digital large diaphragm condenser, the D-01. One would assume the success of the D-01 has led to a further expansion of Neumann’s digital daydream to include their small diaphragm lineage in a digital format.
The KM180 series of condenser microphones are a staple small diaphragm condenser across the globe, owing their heritage to the KM80 series predecessors – the first ever microphone to use 48V phantom power (in 1966). The digital variation on these designs is the KM-D series, and unlike its predecessors comprises a single KM-D body or preamp and a selection of screw-on capsules for cardioid, omni and hyper-cardioid polar patterns. For this review I was sent a KM-D ‘starter set’ comprised of a KM-D body with a 184 cardioid capsule and the S/PDIF connection kit. This arrived in the typical Neumann presentation-grade wooden box and includes a standard mounting clip and foam windscreen.
Available in both black and nickel, the KM-D body and 184 capsule look no different to the current KM180 series. To that end, nothing will be damaged (according to Neumann) if someone inadvertently plugs the mic into a standard analogue cable and hits it with 48V phantom – the KM-D is designed to withstand these indiscretions for short periods of time. Apart from the body markings depicting the AES42 digital XLR connection and the blue LED, the KM-D looks for all the world like a standard KM180. But, of course, the KM-D isn’t a standard mic by any stretch, housing its own A/D conversion electronics and interacting with the ‘outside world’ in ways that no analogue mic ever dreamed of doing. The AES42 data transmits perfectly via standard microphone cables, at lengths of up to 100 metres, at 44.1k. Up to 300m runs can be made at 44.1/48k when using 110Ω AES/EBU standard cabling. This is reduced to 100m again at 176.4 and 192k.
JUST FOR STARTERS
Along with the ‘starter set’ I also received the DMI-2 microphone interface for the review – the more comprehensive method of connecting two KM-D mics. But before we look at this ‘extra’, let’s firstly investigate the S/PDIF connection kit included with the mic. This is a relatively no-frills version of the DMI-2 and will only operate a single KM-D microphone. Almost as large as the microphone itself, the S/PDIF kit provides a single female Neutrik XLR connector – for connection to the mic – on a 900mm cable, which terminates at a Neutrik RCA plug. This is your S/PDIF output from the microphone. Power is supplied to the connection kit via a universal wall-wart power supply, which comes with three commonly used mains input adaptors. It’s a Chinese-made power supply but it’s definitely one of the better supplies I’ve seen – a similar style to what you’d expect to see packaged with more upmarket digital cameras and such. A very similar connection kit is available separately that will output AES/EBU.
The caveat with these ‘starter’ connection kits, however, is that the digital microphone will only operate in its preset (fixed) condition when connected in this manner, restricting you from exploring all the versatility the mic has to offer when it’s connected to the DMI-2. Although the KM-D will operate at various sample rates, the DSP smarts behind it are housed within the microphone body. So if you need to alter the output sample rate (among a raft of other parameters), you’ll need the DMI-2 interface.
But before we look into the DMI-2, it’s worth investigating just how Neumann digital mics interface with your digital inputs. Prior to Neumann’s release of the D-01, Neumann got together with the AES and formulated the AES42 digital microphone standard. The protocol is how all future digital microphones will be configured, with manufacturers such as Schoeps, RME and (of course) Neumann, already on board and churning out AES42-specified microphones and associated equipment. The standard allows for a 10V phantom power voltage that can be modulated to allow switching of a microphone’s features, such as sample rate, gain, polar pattern and sync that one might be making to a digital microphone’s setup.
The big issue with the KM-D is that there’s no external mic preamp as such – preamplification and A/D conversion must occur within the microphone itself. Being a digital, DSP-driven device, a mic such as the KM-D provides many more control parameters than mere gain and clock frequency. Within the DSP of the KM-D are gain control, preamp attenuation, polarity inversion and high-pass filtering. There’s even a peak limiter and compressor that can also be set to ‘de-ess’. And if that’s not enough built-in smarts for one microphone, there’s also a test-tone generator that will burst forth a 1kHz tone along with white and pink noise. All these attributes are accessed via the DMI-2 interface, which is, in turn, controlled via Neumann’s remote control software (bearing the rather Germanic title of ‘RCS’). But more on the software in a moment. Now to the DMI-2…
NEED TO KNOW
EXPLORING THE HIDDEN EXTRAS
The DMI-2 interface is a sturdy aluminium unit that will drive two digital mics – assuming those mics operate according to the AES42 spec. Two AES42 inputs (standard XLR inputs) and two AES/EBU digital outputs will link your mics to your digital inputs. (You can also set the unit to output both mics from a single AES/EBU output if you’re dealing with XLR AES inputs.) Wordclock BNC I/O ports are an inevitable addition. Two RS485 connectors (similar to a Cat-5 ethernet connector but with an additional twisted pair) serve a couple of duties. The first links to your PC or Mac via a supplied USB converter; the second acts as a link to further DMI-2 units. When combining units, the RCS software will operate up to eight digital microphones simultaneously. A final RS232 port allows remote muting of each mic and switching of the LEDs mounted in the mic – ideal for broadcast/voiceover applications, for example.
BUNCH OF RCS
Getting back to the RCS control software, this is a utilitarian interface, offering a channel strip-style GUI for each microphone connected to the DMI-2. Windows 98 SE, ME, 2000 and XP and Mac OS version 8.6 or higher are all supported (incredible, someone still supporting pre OSX operating systems on the Mac platform!). Operating firmware for the mic can be uploaded via RCS and entire setups can be saved for later retrieval. This in itself is quite an advantage, allowing complete recording setups to be recalled, from mic gains through to compression settings. I can see facilities such as the Sydney Opera House jumping onto these systems immediately – for perfectly reproducible microphone trees, for example.
So from the top of the channel strip is the microphone model, then a polarity adjustment, from omni through to figure-8 with 15 positions in between – cardioid being in the middle, of course. Next up is a low-cut filter with three positions: 40, 80 and 160Hz, followed by a pre-attenuation section (or pad), with notches at 0, –6, –12 and –18dB. Following on from this is the gain section, where clicking on the displayed gain level opens a gain slider providing from 0 to 63dB of gain. Below this is the aforementioned test-tone generator and sample rate selection menu. The KM-D will clock to: 44.1, 48, 88.2, 96, 176 and 192k sample rates and, of course, wordclock. There’s also an additional option to ‘freewheel’ the sample rate independent of the wordclock or the clock speed of the equipment the mic is connected to. Following down the strip is the comprehensive compression section, which provides eight ratio settings from 1.2:1 through to 100:1. Eight attack settings go from 0ms (I don’t know how that works) up to 100ms. This can also be set to de-ess at 1, 2 and 4kHz notches. Finally, the peak limiter will rein in those transients anywhere between 0 and –15dBFS.
As well as the propensity for saving unique setups, the active settings can be stored in the DMI-2 interface, retaining its setup – a stand-alone mode, if you will. Alternatively the settings can be stored in the microphone itself, so if you find a digital mic behaving oddly, it could be that your dynamics are still set to ‘stun’ within the mic’s own DSP. At the bottom of the strip are mute, phase, LED on/off buttons and metering for input and gain reduction. Then a nice little text box appears for labelling channels. Moreover, the KM-D184 manages to process all this in a mere 49 samples. That’s a latency of 1.1ms at 44.1k or 0.255ms at 192k – pretty slick processing in other words. What I couldn’t find within the software or the manual, however, was a method for ganging two channels together for stereo operation. Whether this is because I needed two mics to instigate the option or it doesn’t actually exist, I don’t know.
When you consider all these feature as a single microphone package, it’s a remarkable feat indeed. And although the initial cost of these mics may seem a little over the top, when you consider you’re getting a comprehensive dynamics processor and the cleanest preamp you’ll ever clamp your ears around into the bargain, the whole deal begins to look incredibly attractive. Add to these ‘extras’ the fact that you’re dealing with one of the most oft-used small diaphragm condensers in recording history and the package is compelling indeed – a prerequisite for many facilities in the near future I’m sure.
DIGITAL SOUNDINGS
As for the sound of the KM-D? I was particularly impressed. The analogue version of the KM184 is a veritable standard for drum overheads, acoustic guitars and close miking of orchestral instruments. The difference here is the incredible increase in headroom achieved with the digital interface, all without the inherent noise and interference of an analogue preamp, compression and analogue cable runs. I immediately set the KM-D onto my acoustic guitar and I must say I’ve not used a nicer small diaphragm condenser – it blitzed my AKG 451Es and Oktavas – the Neumann offers a much more transparent and controlled sound than either of my (admittedly cheaper) small diaphragm condenser choices. Another major difference is how far you can push the KM-D; with a 144dB SPL rating you’ll find it difficult to overload this mic (the analogue version tops out at 138dB). So at the end of the day I packed the KM184D away – not wishing to drool over it any longer – pushed it to the back of my mind and budgeting list. But when it does come to my next microphone purchase I do believe I’ll be merrily skipping down the AES42 road – simply stunning reproduction.
RESPONSES