The standard version of the Stereo Mastering Equalizer has a boost/cut
range of +/- 12 dB for all bands. All 0 dB positions have center detents and
are precisely calibrated. The range around the 0 dB point is stretched to make
very small settings easy. The TM205 is also available with +/- 6 dB and +/- 20
dB control range for other applications.
The three fully parametric bands are implemented as active 'Vienna Bridge' circuit. Each band has a gain control, q-factor control and center frequency control. The sweep ranges of the bands have huge overlaps; each band allows a frequency variation of 1 to 100. The Stereo Mastering Equalizer is manually calibrated for optimum tracking accuracy between the stereo channels. All components that affect the tracking accuracy are handpicked.
The three fully parametric equalizer bands of the TM205 cover the entire audio band from 20 Hz up to 25 kHz. The sweep ranges of the bands have huge overlaps. Between 60 Hz and 7 kHz, two bands can be used; all three bands can be tuned within the range from 250 Hz to 2 kHz. It is possible to use one band for a global correction with a wide q-factor setting while another band with narrow bandwidth is used in the same frequency range for small corrections of formants or interfering frequencies.
The sweep ranges are 20 Hz to 2 kHz for MID1, 60 Hz to 7 kHz for MID2 and 250 Hz to 25 kHz for MID3. The frequency controls are implemented with negative logarithmic law. Due to the large control range, the MID1 Equalizer is actually a low eq, while the MID3 band can be used as high eq as well.
Using narrow q-factor settings at the upper end of the audio band can produce silky luster highs; a boost in the range below 60 Hz with a medium bandwidth supports the 'fundament' of the mix, while narrow settings at the base frequency of a kick drum result in high 'pressure' in the bass range without loosing transparency at the low end.
The q-factor control range is the same for all fully parametric bands and covers a range from about 5 octaves for global corrections down to a third for subtle filter settings.
The fully parametric equalizer bands are based on the 'Vienna bridge' circuit that we at adt-audio have been using since more than 25 years. The circuits allow independent adjustment of boost and cut, center frequency and bandwidth in very wide ranges. Even with drastic filter settings, the equalizer behaves free from distortion, TIM and slew rate related effects; the results are always musically.
The high and low bands for global corrections complete the feature set of the stereo mastering equalizer. The circuits of these bands are based on soft R/C filters with a steepness of 6 dB/oct.. The characteristics of each filter can be modified by a set of switches. Four different settings are possible.
The high equalizer is a soft shelving filter with a corner frequency far beyond the audio band at the default setting. It produces silky sounding highs when boosting. Using the switches changes the characteristic to a very soft bell for high frequency 'pressure'. By combining both switches, the weakly pronounced center frequency can be set to 12 kHz, 8 kHz or 4 kHz. The bandwidth of the filter characteristics is also changed with the frequency.
The low equalizer is a soft bell. The bandwidth is quite similar to a shelving filter; however, boosting subsonics is effectively prevented. An additional high-pass filter is not necessary in most cases. In addition, the bell filter offers advantages as far as the low frequency phase response is concerned. The two switches select the center frequencies 40 Hz, 60 Hz, 100 Hz and 160 Hz.
The headroom is + 30 dBu throughout the entire stereo mastering equalizer. At linear settings, the output noise is less than -90 dBu RMS, which results in a total dynamic range of at least 120 dB.
The TM205 is a 4U ToolMod that fits into two slots of the horizontal 1U
high ToolMod Frames. The vertical version fits into a slot of a 4U
high ToolMod Frame. The Stereo Mastering Equalizer is available with +/-
6 dB, +/- 12 dB, or +/- 20 dB boost/cut range.