Behringer XR4400 manual Flexlink function, IRC characteristic curve

MULTIGATE PRO XR4400

gain reduction applied. Thus, you can use smaller amounts of gain reduction making it possible to retain the natural sound of the program material—in particular, with signals that contain plenty of interference noise.

5.2.5 IRC circuit (Interactive Ratio Control)

In conventional expanders the control processes cut the signal abruptly below the threshold, which usually leads to less satisfying results, because the onset of the control function becomes audible. When inaudible expansion is needed, it is therefore better to use a “soft-knee” characteristic around the threshold point that allows for a smoother transition.

The BEHRINGER MULTIGATE PRO uses the newly developed IRC expander (Interactive Ratio Control) whose attack time and ratio characteristics vary automatically depending on the program material.

The IRC expander is switched on with the MODE switch. Low ratios and hence subtle expansion produce a “smooth” transition, while higher ratios and heavy expansion result in a “steeper” transition between the characteristic curves.

This so-called interactive, i.e. nonlinear IRC characteristic is perfectly adapted to human hearing: critical wanted signals around the threshold point are less expanded, while interference signals with lower levels (e.g. background noise) are processed and faded out with a higher expansion ratio.

Fig. 6.3: IRC characteristic curve

The result is an expansion process that is less difficult to adjust and more tolerant towards wanted signals whose levels are only slightly above the level of the background noise.

5.2.6 RATIO function

The ratio of the input-level-change vs. output-level-change after the onset of the control process, i.e. after the signal has dropped below the threshold, is called expansion ratio and can be set with the RATIO control. RATIO settings from 1:1.2 through 1:4 give you smooth and exactly dosed downward expansion.

The RATIO scale printed on the front panel indicates the expansion ratio in decibels, i.e. it shows you the decibels by which the output signal is cut for each reduction by one dB of the input signal.

With a 1:1 ratio the output signal level is the same as the input signal level, i.e. there is no signal change. A ratio of 1:2 means that the output signal is reduced by 2 dB when the input signal drops below the threshold by 1 dB. Accordingly, with a ratio of 1:4, the output signal is cut in level by 4 dB when the input signal is 1 dB below the threshold.

5.3 FLEXLINK function

The four channels of the MULTIGATE PRO can be operated both independently of each other and in couple mode. In particular, when you record a choir it will be useful to couple the individual microphone channels. For example, when all microphones are controlled by one singer, all vocals start and stop precisely at the same

5. TECHNICAL BACKGROUND 17