Base, full-line printhead, and printing apparatus

A base in which a plurality of element substrates each including a plurality of driving elements are arranged in an arrayed direction of said plurality of driving elements, comprising:

• a first terminal configured to input a first signal as a differential signal;
• a first pair of signal lines configured to transfer the differential signal of the first signal from said first terminal to said plurality of element substrates;
• a second terminal configured to input a second signal as a differential signal;
• and
• a second pair of signal lines configured to transfer the differential signal of the second signal from said second terminal to said plurality of element substrates,
• wherein each of said plurality of element substrates includes:
• a first amplifier configured to amplify the differential signal of the first signal transferred via said first pair of signal lines;
• a second amplifier configured to amplify the differential signal of the second signal transferred via said second pair of signal lines;
• and
• a first control circuit configured to control to change a gain of said first amplifier based on a first control signal from outside.