We reckon that the low ripple of the eq’s overall frequency response, shown in Diagram 2 is caused by small tolerances of the center detents of the gain controls. However, these tolerances cause no error in the channel tracking accuracy that is better than 0.2 dB. The Diagram no. 3 shows these differences with a zoomed dB scale. Who is looking for a higher precision, will not get around buying a mastering equalizer with stepper switches at a considerably higher price, which is presumably more expensive than the entire adt-audio mastering set including the extensive dynamics section.

The phase accuracy between the stereo channels, which is of elementary importance, remains exemplary flat in spite of the minor changes of the frequency response.

The common mode rejection ratio of all line inputs was in the range of –80 dBr, depending on the particular module and the test frequency; the cross talk between the stereo channels, shown in Diagram no. 6, remained below –70 dBr up to a frequency of 15 kHz.