User manual BEHRINGER SNR2000

[. . . ] SNR2000 Users Manual Version 2. 3 June 2002 DENOISER® www. behringer. com ENGLISH DENOISER SNR2000 SAFETY INSTRUCTIONS CAUTION: To reduce the risk of electrical shock, do not remove the cover (or back). No user serviceable parts inside; refer servicing to qualified personnel. WARNING: To reduce the risk of fire or electrical shock, do not expose this appliance to rain or moisture. This symbol, wherever it appears, alerts you to the presence of uninsulated dangerous voltage inside the enclosure voltage that may be sufficient to constitute a risk of shock. This symbol, wherever it appears, alerts you to important operating and maintenance instructions in the accompanying literature. [. . . ] While the unit calibrates automatically, the LEDs might indicate values that deviate from the values stated by the controls and scales on the front panel! 2. 3 Operation of the expander section The noise reduction system of the DENOISER is based on two signal processing techniques, which can be used separately but may also be combined with each other: in addition to the dynamically controlled low-pass filter mentioned above, the DENOISER features a so-called downward expander which uses a second noise reduction process to eliminate remaining interference noise. A downward expander automatically reduces the overall level for all signals below an adjustable threshold and therefore extends the dynamic range of the program material. Changing the variable release time and the expansion ratio enables the expander to operate as a noise gate. Expanders generally function with a flat ratio curve, so that the signal continually fades. Noise gates however, can be seen as a special type of expander. They normally work with a more exaggerated ratio and radically attenuate the signal if it falls below the threshold. + The following explanations also apply to the gate function, because the gate is a special form of the expander. 12 2. 2. 3: The function of an expander 2. 4 The IRC expander of the DENOISER The response characteristics of conventional expanders tend to cut the signal abruptly and the result is generally unacceptable, since the effect is clearly audible. Inaudible expansion, however, requires a gentle Soft Knee characteristic due to a continuous transition of the straight lines at the threshold. A newly developed IRC (Interactive Ratio Control) expander has been integrated into the DENOISER. The ratio curve characteristic automatically adapts itself, dependent on the program material. With low ratios and a slight expansion, the transition is gentle, whereas higher ratios and increasing expansion will result in harder transitions within the curve. The IRC expander is therefore equipped with a soft, interactive non-linear ratio curve which is best suited to the human hearing. Critical signals around the threshold level are processed with low expansion ratio settings, whereas low signals will be subjected to an increasingly higher ratio which will result in greater attenuation. Fig. 2. 4: IRC curve characteristic of the expander The result is an expander which can be adjusted without the risk of alienating the overall sound. Furthermore, the expander is more tolerant towards those usable signals which appear slightly above the noise floor. 2. OPERATION 13 DENOISER SNR2000 2. 4. 1 THRESHOLD control The THRESHOLD control of the expander defines the operating level. It stretches across a very wide range and therefore applies to all working levels. Input levels above the adjusted threshold point do not experience any change. However, if the level falls below the threshold the dynamic process is active. For example, if the THRESHOLD control was set at 0 dBu and the input signal drops below 0 dBu, downward expansion will begin. In typical applications the setting of the threshold control should be between 5 and 20 dB above the quiescent noise floor of the input signal. For example, if the quiescent noise floor was -40 dBu, a setting between -35 to -20 dBu will produce the desired expansion. + With the RATIO control set to maximum and the THRESHOLD control set at +10 dBu, an input signal level would have to exceed approximately +5 dBu to produce an output signal. 2. 4. 2 RELEASE control The RELEASE control determines the time the downward expander requires to decrease the level of the output signal. [. . . ] Damages/defects caused by the following conditions are not covered by this warranty: s improper handling, neglect or failure to operate the unit in compliance with the instructions given in BEHRINGER user or service manuals. s connection or operation of the unit in any way that does not comply with the technical or safety regulations applicable in the country where the product is used. s damages/defects caused by force majeure or any other condition that is beyond the control of BEHRINGER. Any repair or opening of the unit carried out by unauthorized personnel (user included) will void the warranty. [. . . ]