ULTRA-CURVE PRO DSP8024
4. “TRUE RESPONSE” CHARACTERISTIC
The BEHRINGER ULTRA-CURVE PRO differs greatly from conventional graphic equalizers, in its filter concept and resulting method of operation. Conventional graphic equalizers are, by the physical nature of their design, subject to strong interaction between adjacent filters, resulting in a difference between the frequency curve suggested by the fader position, and the real frequency curve achieved. This difference itself varies depending on the amount of frequency boost or attenuation applied. The same interaction occurs in digital filters, due to the finite filter slope used. However, digital control allows us to predict these interactions, and—by generating a compensating value for each affected filter—to compensate for them.
The algorithm necessary to achieve this has been specially developed for the ULTRA-CURVE PRO, making it a “true response” equalizer. The advantages of this are directly apparent. Formerly, you had to know exactly what effect a given equalizer setting on your graphic equalizer would really achieve. If you give the ULTRA-CURVE PRO a particular setting, you can be sure that the resulting frequency curve will reflect the visual setting of the frequency filters. The ULTRA-CURVE PRO takes the guesswork and indeed the “witchcraft” out of equalizing. The new control concept of the ULTRA-CURVE PRO does, however, result in it having characteristics which need to be explained here. Equalizer settings with extreme differences in levels between adjacent frequency bands require in some cases internal boosting and attenuation of up to 48 dB. Theoretically, this is quite possible, but can quickly lead to overloading and distortion of individual filters.
Fig. 4.1: Graphic equalizer with a fixed Q of 7
A traditional graphic equalizer tends to overload when several neighboring filters are simultaneously boosted, since their combined effects will be summed, resulting in an overloading of the summed signal. If neighboring filters are widely different in setting they will level out each others effect. This results in little alteration of the processed signal and the need for extreme settings to achieve minimal change
At first glance, the concept used in the ULTRA-CURVE PRO may seem unusual. However, after using it you will realize that the “true response” concept allows you to use the ULTRA-CURVE PRO intuitively, and that it is more straightforward to achieve the desired result. In order to set filter curves with very extreme slopes, the ULTRA-CURVE PRO offers three extra, full parametric equalizers per channel, each having a wide range of settings.
To clearly illustrate the above principles in operation, we give you some examples. The settings shown here are unlikely to be ever used in practice, nevertheless they serve to illustrate the difference between the ULTRA-CURVE PRO and a conventional graphic equalizer.
