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. [. . . ] If, on the other hand, all LEDs light up, the bandwidth is above 20 kHz and the filter has no influence on the usable signal. It proves quite useful to set the SENSITIVITY control in that way that the noise floor causes the first LEDs to light up. + + Please note that this meter is merely supposed to help you adjust the controls. It is recommended to perform A/B comparisons with the FILTER IN/OUT switch to find out which setting suits your demands!Please also note that after power-up the unit needs a few minutes to warm up. 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. 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. [. . . ] Subsequently, the product must be returned in its original shipping carton, together with the return authorization number to the address indicated by BEHRINGER. Warranty services will be furnished only if the product is accompanied by a copy of the original retail dealers invoice. Any product deemed eligible for repair or replacement by BEHRINGER under the terms of this warranty will be repaired or replaced within 30 days of receipt of the product at BEHRINGER. If the product needs to be modified or adapted in order to comply with applicable technical or safety standards on a national or local level, in any country which is not the country for which the product was originally developed and manufactured, this modification/adaptation shall not be considered a defect in materials or workmanship. [. . . ]