The 1066D is completely hand-wired using Carnhill (St. Ives) transformers and has the same mic-line pre-amp as the 1073, with the exception that the 1066D adds a few different frequencies to your pallet.
This unit is popular among guitarists for having a unique mid-range. The original 1066 only had a 10k shelving but this unit offers additional frequencies: 10k Hz,12k Hz,16k Hz, 20k Hz and 24k Hz.
High Frequency: +/-16dB shelving with selectable frequencies of 10kHz, 12kHz, 16kHz, 20kHz and 24kHz
Low Frequency: +/-16dB shelving with selectable frequencies of 35Hz, 60Hz, 110Hz & 220Hz
Mid Range: +/-16dB peaking with switchable selectable centre frequencies of 700Hz, 1.2kHz, 2.4kHz, 3kHz, 7kHz
High Pass Filter: 18dB per octave slope, switchable between 45Hz, 70Hz, 160Hz & 360Hz