Behringer SNR2000 manual Operation of the filter section

DENOISER SNR2000

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FUSE HOLDER / VOLTAGE SELECTOR. Please make sure that your local voltage matches the voltage indicated on the unit, before you attempt to connect and operate the DENOISER. Blown fuses may only be replaced by fuses of the same type and rating. Some models allow for inserting the fuse holder in two different positions, in order to switch over from 230 V to 115 V operation, and vice versa. Please note that for 115 V operation outside Europe, you need to use a fuse of a higher rating (see chapter 6 “SPECIFICATIONS”).

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Use the enclosed power cord to connect the unit to the mains.

These are the balanced 1/4" TRS and XLR AUDIO INPUTS of your DENOISER.

These are the balanced AUDIO OUTPUTS of the DENOISER, available as 1/4" TRS and XLR connectors.

2. OPERATION

The need for an all-purpose and professional noise reduction system was the basis of the development of our

DENOISER.

The system design has to meet the following criteria:

1.All-purpose application: the noise reduction design is aimed to operate with both all types of instruments as well as with all composite signal sources.

2.Most effective noise reduction while influencing the signal to the least possible extent. The signal’s original sound as well as its attack response remains unaffected.

3.No side effects such as pumping, noise tails, etc. known from conventional circuitries.

4.Simple operation through comprehensive automation of control processes.

To obtain maximum performance, it is necessary to understand what is achieved by each of the separate filter and expander sections and how they perform together. Once you understand how these circuits work, it will be easier to set up the controls correctly to suit any application.

The noise reduction effect of the expander section is active only when signal levels are low. The filter section, on the other hand, is active at all times over the complete dynamic range. Since the filter section is always active, let us look at what is happening in that circuit first:

2.1 Operation of the filter section

2.1.1 The masking effect

The function of the BEHRINGER DENOISER is based on the “masking” effect: noise will be masked and thus becomes inaudible, as soon as considerably louder sound signals are added.

One of the basic components of BEHRINGER circuitry is a dynamically controlled low-pass filter which allows low frequencies to pass but filters the high-frequency information, depending on the music material. In contrast to conventional noise filters with fixed cut off frequencies, the DENOISER shifts the cut off frequency between 800 Hz and 20 kHz, depending on the program material. This is the range where noise is considered most annoying. The cut off frequency of the filter depends on both the input level and the frequency range of the audio signal.

2.1.2 The dynamic low-pass filter

The filter section features a dynamic low-pass filter which operates as follows: With no audio signal present, the dynamic filter will close down to a user selectable cut off point. This cut off point is adjustable between 800 Hz and 6 kHz. If the cut off was set for 1 kHz, the bandwidth of the filter would be from 20 Hz to 1 kHz. If an input signal had a bandwidth from 20 Hz to 2 kHz, the filter would open far enough to pass up to the 2 kHz frequency and its harmonics, while reducing any noise present from approximately 2 kHz to 20 kHz. If a broad- band signal with frequency components up to 20 kHz appears at the input, the dynamic filter would open all the way to 20 kHz.

2. OPERATION 9