Originally Posted by nanaholic
Q: I want to ask about the newly designed full digital amp "S-Master HX". What has changed by having 4 power source (L/R positive and negative)?
In portable audio it is common for the amp to have a single directional power with one power source, and for those who put in more effort there may be two. In the ZX1 because we have removed the component called the coupling capacitor just before the headphone output, therefore we have selected to use both the positive and negative to create the signal.
So not only there is the pushing force from the "positive", there is also the pulling force from the "negative" thus resulting in much more control, on top of which there is 4 power source so there is sufficient current being supplied, and the result is more control than what we had before as well as it being extremely powerful. Because of this design even overhead headphones can be driven properly, as well as preventing the mixing of the L/R channels thus the use of completely separated L/R power source to achieve better stereo separation.
Because "S-Master" is more prone to power source noise compared with analog amps, to ensure the high quality of the power there is an increase of power supply which leads to increase in cost, but we prioritized the sound quality first.
Q. What is the advantage of removing the coupling capacitor?
Sato Hiroaki [Sound Quality Design]
The coupling capacitor is a part which cuts out the DC signal and only letting through the AC signal. If you are using using either positive or negative directional power, the magnet in the headphone will only move in one direction leading to damage, therefore the coupling capacitor act as a safe guard. However because the capacitor also acts as a high pass filter, this may lead to the bass level is reduced or phase delayed which is a serious short coming.
Because of this, "S-Master HX" uses both positive and negative power using 0V as the centre to move the magnet in both up and down directions, therefore the coupling capacitor is not needed. Due to cost and space on the circuit board this method is usually avoided, but to achieve nice good bass we prioritized the advantage of this set up.