Manual

ManualsBrandsNEUMANN ManualsDigitalDMI-2 portable - Digital microphone interface

Indicators:.........Main/Aux Power, Ext Word Clock,

Valid, Display

Control elements: ........................... 2x push-switch

rotary encoder

CTL (Control interface): .......................1x USB port

Power supply: ...................................... DC 10-18 V,

NP1 rechargeable battery or

AC/DC converter (Sound Devices

XL-WPH3 recommended)

Power consumption: .......................................<8 VA

Dimensions: ...........(W x H x D) 186 x 44 x 126 mm

Weight: ...............................................approx. 625 g

7. Additional information

7.1 AES42

This standard is based upon the use of a 2-line

balanced cable (AES/EBU cable; for short con-

nections conventional “analog” cable can also

be used). The power supply for digital micro-

phones is deﬁ ned as Digital Phantom Power (DPP)

with +10 V and max. 250 mA. Modulation of the

phantom voltage generates a remote control data

stream which is transmitted to the microphone

(+2 V pulses).

The data format of the digital audio signal trans-

mitted from the microphone complies with the

AES/EBU (AES3) standard. The user bits deﬁ ned

in this standard are intended for the transmission

of various types of information. The AES42 stan-

dard deﬁ nes the signiﬁ cance of these user bits

with regard to digital microphones. In the DMI-2

portable, these data are separated from the audio

signal and are transferred to the computer via the

USB control interface.

Fig. 4 shows a simple functional diagram of a mi-

crophone interface with an AES42 input and an

AES/EBU output.

7.2 XLR cables

The length of cable that can be used from a digi-

tal Neumann microphone to the DMI-2 portable is

dependent upon the type of cable and upon the

sampling rate (word clock frequency) selected.

For cable lengths of up to 100 m with a sampling

rate of 44.1 kHz or 48 kHz, high-quality “analog”

XLR 3 cable (e.g. the Neumann IC 3 cable) can be

used. For greater cable lengths, the use of AES/

EBU cables (110 ohms) is required. If AES/EBU ca-

bles are used, the following cable lengths are typ-

ical: Up to 300 m for sampling rates of 44.1 kHz

or 48 kHz; up to 200 m for sampling rates of

88.2 kHz or 96 kHz; and up to 100 m for sampling

rates of 176.4 kHz or 192 kHz.

Attention: If a long cable is used to connect the

microphone and the DMI-2 portable, the DC re-

sistance of the cable used must not exceed a

speciﬁ ed maximum value, since excessive DC re-

sistance would result in an impermissible voltage

drop in the phantom power. The following formula

applies:

Rc/2 + Rs < 18 ohms

Rc = DC resistance of the individual cable core,

Rs = DC resistance of the shield or the GND re-

turn line.

The length of cable that can be used from the

DMI-2 portable to subsequent equipment (e.g. a

digital mixing console) is substantially dependent

upon the technical features of the subsequent

equipment. Thus no speciﬁ c statements can be

made concerning the cable length. In case of

doubt, the use of AES/EBU cables (110 ohms) is

recommended.

7.3 Storage and reloading of the previous

conﬁ guration

All of the settings which are in eﬀ ect when the

DMI-2 portable is switched oﬀ are stored internal-

ly, and are automatically sent to the microphone

when the equipment is switched on again. The

most recent microphone settings are restored,

without requiring a connection to the computer

(PC or Mac).

The same procedure is followed if a microphone

is connected to the DMI-2 portable later, after the

DMI-2 portable has already been switched on.

When the RCS control software is started, the con-

ﬁ gurations stored there for all of the microphone

channels are compared with the settings stored in

the DMI-2 portable. If diﬀ erences are detected, a

menu is displayed that asks which conﬁ guration

is to be used (see the RCS Operating Manual).

7.4 Synchronization

The AES42 standard describes the following two

modes for synchronizing the microphone with the

receiver (e.g. a mixing console or the DMI-2 por-

table Digital Microphone Interface).

Mode 1: The microphone operates asynchronous-

ly, using the sampling rate of its internal quartz

oscillator. In this case, a sample rate converter is

required at the receiver. It should be noted that

sample rate converters can impair the signal qual-

ity in terms of dynamic range and enlarge the la-

tency time.

Attention: This mode is not supported by the

DMI-2 portable

Mode 2: The microphone is synchronized by the

DMI-2 portable. In this case, the DMI-2 portable

performs a frequency/phase comparison between

the word clock signal recovered from the micro-

phone signal, and the word clock of the DMI-2 por-

table. From the phase deviation thus determined,

the DMI-2 portable calculates a control signal

which is transmitted via the remote control data

stream to the microphone, where it controls the

frequency of the internal quartz oscillator.

Via the BNC output, the internal word clock gener-

ator of the DMI-2 portable can be used to synchro-

nize additional DMIs and connected equipment,

such as a mixing console.