Niveau Filter with High-Low EQ for Stereo Mastering
The Niveau Filter W795 is a special combination of different equalizers for global corrections of the frequency response with stereo mastering or mixing. The four filter sections of the W795 allow global treatment in versatile ways by controlling the high-low balance and by boosting or cutting the mid range as well as corrections at the upper and lower limit of the audio band. Such filters are proven and tested for their behavior in practice for decades, since they where part of the AT versions of the large format console master sections ever since.
The combination of filters for global corrections in the W795 Niveau Filter is an ideal extension to the fully parametric Stereo Mastering Equalizer W796.
These filter sections allow fast and effective adjustments of the basic character of any mix. Matching high/mid/low relations of the titles of a complete production can be accomplished very fast. Of course, repair work is possible as well.
In many cases a mix is quite okay as far as the relations between the instruments are concerned; however, the entire mix won't match other, similar productions or other titles of the same production. Global correction that are necessary in these cases can be accomplished precisley and fast using the niveau filter. Very often, the necessary corrections are possible instantly at hand.
The filter comes with well-adapted control ranges for stereo mastering. The graphics show the standard version, if there is any, that has a boost/cut range of 6 dB for the niveau filters and 10 dB for the high and low EQ's. All EQ bands can have custom ranges without additional charge between +/- 6 dB and +/- 16 dB, which is the maximum possible boost or cut.
The Niveau Filter has been used since the 1950th in German broadcast network consoles. The device was designed to correct room specific peculiarities. In our application of the principle, we use two different controls, as described above. Over the years, the characteristics of the curves have been optimized for use with global corrections of final mixes.
The Boost/Cut Filter affects the relation between the high/low range and the mid frequencies. Turning the control to the right increases high and low frequencies, while cutting reduces high and low simultaneously. The neutral frequency is 800 Hz, the curves are optimized for that kind of regulation and have a special S shape that leaves the mid range unchanged while affecting high and low in an appropriate relation.
The Balance Filter corrects the high/low relation and leave the neutral frequency of 800 Hz unchanged. In one direction of the control the filter boost high frequencies and cuts low frequencies. The other direction reduces high frequencies and boosts low frequencies. The curves are also adapted to this regulation and have a weakly pronounced s shape with corner frequencies close the 800 Hz.
The high EQ is a baxandall equalizer with shelving characteristics. In difference to other EQ's of that kind, it has a steepness of 9 dB/oct.. The steepness is constant and not modified with the boost or cut. The frequency can be sweeped between 4 kHz and 35 kHz. The boost/cut setting has no influence on the response of the filter curve. Setting the filter to a frequency of 20 kHz results in a curve that boosts or cuts only the range above 15 kHz, even with very small changes. This design allows modifications only in the desired frequency band, which is otherwise only possible with a bell type, fully parametric filter. However, the curve of the high EQ is a shelving curve that does not fall back above the selected frequency like a bell type filter. The boost/cut range of 10 dB is well adapted; however, 6 dB are possible as well. The niveau filter W795b adds a steepness select to the high EQ. With this option, a 3-position lever switch changes the steepness from 9 dB to 6 dB or 3 dB per octave.
Like the high EQ, the low eq is a shelving filter with a steepness of 9 dB/oct. It works just like the high EQ, has the same benefits and behavior but the curve is mirrored. The sweep range starts far below the limit of the audio band at 15 Hz and reaches up to 500 Hz. This range allows influencing the 'belly' of the mix as well as correction in the bass range.
The device is internally and externally balanced. Input s and outputs can be balanced and grounded (electronically balanced) or balanced and floating, using oversized torodial transformers. The maximum level is + 30 dBu. Due to the internally balanced circuitry, the internal headroom is also + 30 dBu. The Niveau Filter W795 has a dynamic range of more than 120 dB RMS. The hard bypass switches the entire device in and out.
The Niveau Filter with elliptic Equalizer W794 is an alternative to the W795, if there is no other device installed that offers an elliptic eq.
The Niveau Filter W795b is almost identical to the W795 but adds steepness selection for the high and low equalizers.
Additional modules for global corrections are the Stereo High-pass Low-pass Filter with Notch Filter W792m and the Stereo High-pass Low-pass Filter with Phase Correction W790.
The module is a V700 standard device that fits into all standard frames.