Nagra VI: a 6-channel 24-bit high-end portable digital audio recorder with an internal hard disk and compact Flash drive.
The development period of a digital audio recorder for the professional cinema, television and music industry lies somewhere between five and ten “man” years depending on how much technology is borrowed from other existing products.
The Nagra VI does have certain elements derived from other Nagra recorders, such as time code, hard disk and compact flash technology but the majority of the machine is entirely new. In terms of the digital platform, upon which all the digital signal processing and command structure is performed, Nagra has implemented a totally new approach. In analogue terms, the line input circuitry and microphone pre-amplifiers, although inspired from the Nagra D and Nagra V are of a totally new design. The recently introduced RoHS requirements were a good reason to redesign all the electronics with the most modern techniques available today.
The most advanced Nagra recorder ever
As a result, the Nagra VI, is probably the most advanced recorder, in technical terms, that has ever come out of the Cheseaux factory. The introduction of this new recorder has been anticipated for quite some time and this is a good opportunity to look into the details of the recorder and to answer some of the open questions.
The Nagra VI is, as its name suggests, a six-track recorder. These six tracks are recorded to an internal IDE hard drive. A removable compact flash slot allows either copying of the master recording or copying of various combinations of track selections. The recorder has six analogue inputs on XLR connectors, four of which are equipped with extremely high quality microphone pre-amplifiers. Two of these connectors double up as AES A and B inputs for connection to digital signal
sources.
Four analogue inputs, two digital
Looking in more detail to the microphone pre-amplifiers, they not only offer +48V phantom powering, as one expects, but they are also equipped with in-house wound transformers (when set to the dynamic position) offering an improvement of more than 6dB in the noise floor over the equivalent transformerless inputs. Fitted with an integrated “vortex” filter, these pre-amplifiers can be used in the windiest conditions imaginable, without suffering from the “popping” traditionally associated with outdoor operation. Naturally this does not eliminate the need for proper microphone protection, but is a great help to the user in unpredictable circumstances. They have been designed to be accurately matched in sensitivity to the various different types of microphones through individual sensitivity selectors for each pre-amplifier. Digital pots on the front panel give level adjustment to the four pre-amplifiers, while the remaining two analogue inputs can be level set in the menus. The choice of inputs, along with all other machine parameters, is selected through a clearly laid-out menu system displayed on a 3½” colour TFT screen. This screen has been specially selected as it is “sunlight readable” and has a very large viewing angle. The controlling software for the display has been written in such a manner as to allow the permanent indication of important information (TC, track, etc.) even when browsing the menus.
Principal operation of the Nagra VI is achieved using the traditional rotary main function selector placed in the standard location on the right side of the front panel. This switch not only follows tradition, but also frees up space on the front panel to allow unimpeded access to other principal controls. The audio tracks can be monitored as required, using a selection of channel switches also located on the front panel, via either of the two ¼” jack headphone connectors.
Total compatibility
The digital portion of the Nagra VI is based on 16/24 bit files recorded in either monophonic or polyphonic Broadcast Wave file formats at sampling frequencies up to 96 kHz with iXML compatible meta data. The time code system covers all traditional SMPTE/EBU frame rates and will allow 0.1% pull down for NTSC compatibility. The 23.976 time code rate is also supported for the modern 24P high definition digital video format compatibility. The entire heart of the Nagra VI is clocked from a Stratum III quartz guaranteeing a maximum drift of less than three ppm throughout the temperature range from -20°C to + 70°C over a 15-year period. Powering of the recorder is achieved either using external DC or detachable battery boxes containing a choice of different capacity lithium-ion sealed battery packs. The smallest pack offers about four hours operation while the largest in excess of 12 hours. Two female Hirose connectors are located on the left rear side of the unit to allow the powering of external devices such as RF radio receivers. Without going into detail about every individual feature implemented, all the expected functions such as pre-recording buffer, two M/S decoders, audio limiters, output dithering, chase synchronizing, word clock in /out, analogue and digital outputs have been included.
Two USB ports, one “Host” and one “Device” allow not only the recorder to be connected to a PC/MAC and appear as a generic hard drive for rapid file transfer, but also a multitude of external communication possibilities to be considered. Nagra engineers feel that the ergonomics of the display and general lay-out of the front panel makes the need for a PC software (as developed for the Nagra D and Nagra V) unnecessary, although the possibility of connecting a PC for diagnostics or input of meta data from an external keyboard are likely future software updates for the host USB port. Any software updates are made by simply downloading the file from our web site onto the CF card, and inserting it into the slot. No recorder ever suits every single application perfectly, but the aim of the development of the Nagra VI was to cover as many bases as possible for a price that is not prohibitive, while maintaining the Swiss tradition of precision, reliability and excellent performance specifications.
Check the Nagra website for detailed product specifications.