Terry Nelson of Studio Equipment, Switzerland reviews NTI's Digirator DR2, a reference grade digital audio signal generator with transformer balanced AES3, S/PDIF, TOS-Link and ADAT outputs.
Product Overview
In terms of layout the unit has a large LCD screen, central rotary wheel with enter key, four function keys (escape – wave – level – frequency), a sens key, mute key and combined on/off and backlight button.
These keys provide direct access to the various test signals, signal level and frequency of the test signal where appropriate, with the sens button changing the increments of the output level from fine to coarse. The rotary wheel allows for both navigation around the LCD screen and the adjustment of settings, with the enter button selecting the function required.
The "Digirator" provides outputs for both professional and consumer digital formats. Connectors include an XLR-3M for AES/EBU, a coaxial (RCA) connector for 75 ohm/SPDIF and an optical connector for Toslink stereo and ADAT signals. Additional connectors include a USB port, the external power supply jack and an XLR-3F connector designated the sync input for AES3, Word Clock and Video.
The XLR and coaxial outputs are transformer-isolated in order to be earth-free and are resistant to Phantom Power.
In Use
Taking a closer look at the test signals and functions. The analogue test functions found in the "Minirator MR2" are present in the DR2. Those include Sine Waveforms, Sweep Signals, White Noise, Pink Noise, Polarity Test Signal and a Delay Test Signal. The two extra signal files are Dolby and DTS.
These files are non-linear PCM and recorded at 48kHz, with the encoding having been done on certified Dolby and DTS equipment.
The Dolby/DTS signals consist of various formats with the following test signals for each format. Due to the size of the Flash memory, not all of the Dolby and DTS test signals can be incorporated and these are available on a CD supplied with the unit. In addition, Dolby Digital Plus and DTS High Resolution Audio test signals are in preparation and will be available for download in the future.
The icing on the cake is the measurement functionality. Transparency measures the transparency – or digital integrity – of a system, this being critical for non-linear applications such as surround.
I/O Delay allows the latency of a system to be measured in milliseconds or PAL and NTSC frames. The input impedance and sampling rate (32kHz to 48kHz) will need to be adjusted accordingly. In the case of unequal delay times for the A and B channels, these are displayed alternately.
Conclusion
The NTI DR2 "Digirator" is a little gem of a test instrument and should be a required item for your test equipment kit. It is easy and intuitive to use and also provides a useful education for some of those hazy points of digital audio! The flexibility of a wide range of test signals plus those in Dolby Digital/Dolby E/Pro Logic II and DTS makes it an ideal source for testing signal chains as well as general troubleshooting and verifications. Highly recommended!