Behringer Ultramatch SRC2000

Sep 1, 2003 12:00 PM, By John S. Landry, CSRE

The Behringer Ultramatch SRC2000 is a digital processor, format converter, signal corrector and a digital distribution panel. It can accept digital signals encoded in any of three formats: AES/EBU, S/PDIF and TOSLINK. It can also accept those signals at any digital sampling rate from 25kHz to 60kHz, and it can accommodate changing copy and emphasis coding bits, remove jitter and change the corrected and cleaned up signal to one of two standardized bit rates while simultaneously feeding that signal to three separate and isolated outputs in AES/EBU, S/PDIF and TOSLINK formats. It occupies 1RU, has a sleek, all-black front panel and uses a standard IEC power cord.

It is not uncommon to have audio from different sources with incompatible formats, for example an ISDN codec and a digital hard disk editor. Many times the incompatibility would be an issue of connectors, such as an AES/EBU output from the codec on an XLR and a S/PDIF input to the hard disk editor. Other times the sampling rate of the codec would not be supported by the digital recorder being used. This simple task would require an analog transfer to be made between the two devices, costing time and sometimes adding artifacts to the audio later on in the session. One afternoon after I had carefully explained a digital incompatibility like this to a producer, she walked away muttering that digital was supposed to make things easier. In one unusual case, I knew of a facility that did the digital/analog/back-to-digital transfers using a cassette deck. There are better ways.

I had a situation where an incoming feed from an ISDN codec was being used in a voice-over session. The engineer wanted to make a safety on a DAT as well as record right into the hard disk system. Because the AES/EBU and S/PDIF formats do not allow for bridging like an analog audio signal, this was not possible. Complicating things further was the sampling rate — the sender refused to use any other sampling rate than 32kHz (claiming that it sounds the best that way) and the hard disk system wanted 44.1kHz. The Ultramatch has three outputs, it can function as a distribution amplifier, providing something for the DAT and the hard disk while also converting the codec audio to 44.1kHz.

The Ultramatch is a surprisingly simple box with just eight small buttons and a neatly organized panel of LEDs. But don't let the simplicity fool you. The Ultramatch accepts the digital audio and converts it up to a high oversampling rate (about 65,000 times or 3.2768GHz). In this mode the digital picture is now made up of several million samples, so the potential resolution is much better. An interpolation algorithm is used to fill in the digital waveform, all the while checking for errors and fixing them. When the signal is done, it converts everything back down to 32kHz or 44.1kHz and it is put out in all three formats to feed your devices. All inputs and outputs, except the optical TOSLINK, are transformer balanced. The manual claims “THD under 0.001 percent [with] noise below -95dBfs.” Though it doesn't specify further, the presumption is that this is the maximum amount of noise and THD the Ultramatch adds on top of whatever noise is inherent in the originating A-D converter and the receiving D-A converter.

In my experience, I have yet to experience any ill effects from this processor. The Ultramatch has an anti-aliasing filter that is self-configuring. It also will allow copyright-protected material to be copied, although the manual cautions you that it was not intended to be used solely to make illegal copies of copyrighted work. The emphasis bits, which the S/PDIF format handles differently from AES/EBU, can be eliminated and corrected, which greatly improves the sound. Despite all of this it will not, however, correct certain problems (specifically, it can't undo distortion in a recording due to 0dBfs excesses). Thus an amateur recording will still sound amateur when you are done.

The manual for the Ultramatch could use some improvement. Many phrases are literal translations from German, and it took some time and thought to fully understand them. It would have been nice if the option of 48kHz output had been provided. The manual also indicates that the Ultramatch will not convert, and nor does it pass-through, the Alesis ADAT signal. There is an external timing input on the back of the unit and while the manual explains the concept of its use, it doesn't really specify what format this timing signal (wordclock) should be.

Landry is an engineering technician at CBS Radio/Westwood One, New York City.