Crane Song Insigna
500 Series Valve Equaliser Module
INSIGNA is a 500 Series valve equaliser, using a dual triode circuit with a 12AX7 valve.
It has 3 bands and filters.
The EQ has 24 dB/Octave High Pass and Low Pass filters each with 7 frequencies.
The top and bottom band are shelving each with 8 frequencies
The mid band is peaking with 8 frequencies.
The three bands work by using buffered RC circuits in the negative feedback path around the tube amplifiers. The result is a fat sounding EQ rich in second harmonic triode tube colour.