Behringer SRC2496 Manual - Page 6

6 ULTRAMATCH PRO SRC2496 User Manual (18) The SAMPLE RATE switch selects the sampling rate to which the input signal is to be converted or made available at the outputs. For this purpose, the SRC2496 must be set to internal mode, i.e. it has to function as a master unit (see sections (20) and (21)). Reducing the digital word length (e.g. from 24 bits to 20 bits) also means a reduction of the resolution. The resulting misinterpretations, which are more likely to result by this word length reduction can be purposefully suppressed with the dither function. (19) The LEDs 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz and 96 kHz read the sampling rate selected with the SAMPLE RATE switch. If the sampling rate is preset by an external wordclock or generated via the digital input signal, the LEDs light up constantly, thus reading the external sampling rate (with a deviation of ±2 kHz). The next value (= deviation of >2 kHz) is displayed by one of the LEDs flashing. (20) The CLOCK switch allows you to select the source determining the sampling rate at the digital output of your ULTRAMATCH PRO. (21) The PLL LOCK LED shows you that your SRC2496 is processing properly the wordclock signals applied. The INTERNAL LED lights up when the SRC2496 generates the sampling rate by itself (master), which is the preferred mode for the ULTRAMATCH PRO acting as an A/D converter. The EXTERNAL LED lights up when the sampling rate is governed by an external wordclock signal. The external mode also allows you to generate sampling rates at the output that could not be generated by the SRC2496 as a master unit. When the DIG IN LED lights up, your SRC2496 uses the wordclock signal included in the digital audio signal fed into the unit. This setting is useful if you do not want to convert the sampling rate, but only the format of the digital output signal (S/PDIF to AES/EBU or vice versa). (22) The FORMAT switch determines the format of the digital data stream on the output side, as defined in the Channel Status data. Available formats are AES/EBU and S/PDIF. (23) The LEDs AES/EBU and S/PDIF show the adjusted output format, which is present at all three digital outputs. Using an appropriate cable (see chapter 5.3.5) you could also route an S/PDIF signal from the XLR output to a second unit, in case the RCA output is already in use. (24) Use the WORDLENGTH switch to select the digital word length of your choice (16, 20 or 24 bits). (27) The EMPH LED lights up when the emphasis bit has been set in the output signal. Use the EMPHASIS switch to enable/ disable this function. To avoid sound deterioration, the LED in the output section should read the same status as the EMPH LED in the input section. In the rare case of a signal containing an emphasis bit without any treble boost applied, you can correct this here and switch off the emphasis bit (detailed information can be found in chapter 3.4). (28) The COPY switch (= copyright) allows you to set the status of the copy bits in the transmitted data stream. The LEDs COPY and ORIG inform you about the current status of the copy protection: digital recording only once COPY-LED on ORIG-LED on digital recording not possible COPY-LED on ORIG-LED off digital recording unlimited COPY-LED off ORIG-LED off COPY-LED off ORIG-LED on Tab. 2.1: Overview of copy bit settings If both COPY and ORIG light up, you can make one copy only. Subsequently, the data will be copy protected. If only COPY lights up, digital copies cannot be made. If both LEDs are out, you can make digital recordings without any limitations. Press the switch to change the status of the determining bits and allow for unrestricted copying. ◊ This option applies exclusively to S/PDIF signals, because the Serial Copy Management System (SCMS) exists in this format only. Signals based on the professional AES/EBU format can be copied freely. ◊ If you want to set the digital word length to a lower value (e.g. to record 24-bit signals with 16 bits on CD, MD or DAT), we recommend that you switch on the dither function, so as to limit the distortion resulting from the omission of the additional bits to an inaudible minimum. (25) The LEDs 24 BIT, 20 BIT and 16 BIT read the word length selected. ◊ Even though removing the copyright bit is possible, we would like to alert you about the fact that copyright and duplication rights must be safeguarded. We did not produce this equipment to facilitate illegal copying! 2.2 Rear panel of the ULTRAMATCH PRO (26) The DITHER switch enables/disables the dither function. The corresponding LED lights up when this function is active. Here's a concise explanation of the dither function: Whenever analog signals are converted to digital (numerical values!), the finite number of digits available for the mathematical description of the analog signals (electrical voltages that are constant in the time and value domains) inevitably result in rounding (29) (30) (31) (32) (33) (34) (35) (36) errors and misinterpretations of the analog signals (quantization errors). In particular, signals with a very small amplitude are affected by an audible Fig. 2.6: Mains connector/fuse holder system error known as granular noise. Such errors can be suppressed by adding white noise. This type of noise has an exactly defined amplitude (minimum amplitude that can be detected only by measuring instruments and by no means affects the audio signal) and broadband frequency distribution, and is called dither signal. Combine this with the high (29) MAINS CONNECTOR/FUSE HOLDER. Use the power cord supplied with the SRC2496 to connect the unit to the mains. Please note the instructions given in chapter 1.2. Blown fuses should only be replaced by fuses of the same type and rating. internal resolution of 24 bits, and you can generate an audio signal of excellent quality.