ProAudio Review - December 2008 - (Page 50)

files are quite large, only a basic set is pre-loaded. Additional test files and some instrument sounds are supplied on a DVD. All test signals originate as 48 kHz WAV files, which get internally converted to the desired output sample rate. This limits the highest audio frequency to a tad below 24 kHz, a minor quibble, as the DR2 can’t check the full-range frequency response of a 96 kHz channel. The Digirator offers control over the Pro/Consumer format, Non-Linear, and Emphasis channel status bits. Changing the Emphasis and Non-Linear flags doesn’t change the test signal, but it provides the ability to check the receiver’s response to those flags. Up to 10 specific test setups (waveform, level, frequency, sweep time, etc.) can be stored as Configurations, which can be named (limited to eight characters, so you gotta be creative) via the USB port. In Use The obvious generator functions are very straightforward. Choose the test signal, connect the Digirator to the device under test, and go. The display and menus are intuitive, and the quick access buttons speed adjusting the signal parameters. For the more complex tests, the LCD displays what you need to see including the clock sync source, sample rate and, when running with external sync, the incoming clock frequency. Selecting SWEEP or CHIRP from the Waveform menu pops up a submenu for setting the starting and ending frequency, dwell or sweep time, and for selecting a single or continuous sweep. Selecting FILE displays the current folder and file name. The cursor and scroll wheel are used to navigate folders and select the file with the desired test signal. The Transparency test is a simple go/no-go verification that all the audio data bits pass through the channel unchanged. Passing the test gives confidence that the channel will successfully transmit non-linear (encoded and data-compressed) data such as Dolby and DTS multichannel surround audio formats as well as conventional linear PCM audio. If the test fails, it’s time to get out a serious data analyzer such at NTI’s DL1 Digilyzer to locate the specific problem. The manual is sketchy about what, specifically, is tested in the transparency test, and how to tell whether the test passed or not since it neither says PASS or FAIL. A change in sample rate or changed data bits is indicated by the generic “DATA CHANGED” message, which is indeed suspicious. As long as both ends of the channel are accessible, Transparency can be checked with a single instrument. Two Digirators can be used on opposite ends of the channel, if necessary. In addition to end-to-end testing, a recorder can be tested by recording the Transparency test signal and playing it back into the DR2’s input for analysis. I/O delay is another in-out test, which measures the time required for a pulse to pass through the AD-DA channel. The resolution for this test is 0.1 ms (also displayed as PAL or NTSC Fast Facts Applications Installed systems, maintenance shop, any place where digital audio data needs to get from one place to another Key Features Generates a comprehensive set of test signals including stereo, 8-channel ADAT optical, and Dolby and DTS surround tests at all standard sample rates from 32 kHz to 192 kHz; plays WAV files for special test sequences, odd waveforms, and any audio material up to 20 kHz; outputs are XLR and TOSLink, sync and end-to-end test inputs are XLR and RCA phono; XLR-BNC and RCA-BNC adapters are included. Price $1,850 list Contact NTI Americas | 503-684-7050 | www.nti-audio.com Product Points Really simple to use Generates common wave forms as well as anything you can record Audio bandwidth is limited to 20 kHz for all sample rates Score proofing systemsfor solving digital interfacing A powerful tool problems and that is well worth the cost. video frames). For checking latency through a DAW chain, a display in samples would be convenient. There’s no official estimate of battery life, but NTI says that at trade shows, where it’s continuously on, they get four to eight hours from a set of alkaline cells. Auto shutoff and intelligent control of the display backlight can increase battery life. NiMH or Li-Ion rechargeable cells work fine, though you can’t recharge them in the unit. An optional AC power supply is available for bench use, however the manual recommends battery operation for the cleanest signals. Summary This is a handy gadget for testing digital inputs and transmission chains. It’s easy to use, can go anywhere, and can perform a range of useful tests. It’s a good tool for the maintenance shop or a broadcast facility, but probably overkill for the project studio. My only wish is that the audio frequency range extended to 40 kHz or above, but that would require a significant redesign. 50 ProAudioReview | December 2008 www.proaudioreview.com http://www.nti-audio.com http://www.proaudioreview.com

Table of Contents Feed for the Digital Edition of ProAudio Review - December 2008

ProAudio Review - December 2008 Contents Technically Speaking New Studio Products Opinion: Mastering Matters Review: BIAS Peak Pro XT 6 Review: Zaxcom Fusion ENG Mixer and Multitrack Recorder Review: Sound Devices 788T 8-Track Digital Audio Recorder Review: Universal Audio UAD-2 Solo DSP Accelerator Review: Chandler Limited Germanium Compressor Review: RME ADI-8 QS A/D-D/A Converter Feature: Converters and Clocks: Engineers on Their Choices New Live Products Opinion: From the Road Review: Yamaha IM8 Series Mixing Consoles Review: NTI Digirator DR2 Digital Audio Signal Generator Review: Sencore SoundPro SP495 Audio Consultant Test Set Single Slice

ProAudio Review - December 2008

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