Close-up of the Underside (part 3)
Here we can see the analogue stage that occupies the centre of the PCB. We can see the J-Fet input “Soundplus®” Op-Amp from Burr-Brown (by TI) which is actually a Quad type.
The second pair of Op-Amps inside the case are used as DC servo, to eliminate any need for coupling capacitors.
So yes, the signal path is DC coupled from the DAC all the way to the RCA and Headphone jacks!
As a DC servo not only handles the DC offset in the circuit, but must remove all the signal before feeding the correction voltage into the Audio Path any distortion here will cause problems. The common solution is the use of inexpensive and poor quality Op-Amps for the DC Servo, leading to unanticipated sonic compromises.
As can be seen, passive components for the analogue stage are also at the highest level of Quality, with MELF resistors and C0G capacitors for all critical sections (including the power supply).
C0G Capacitors
MELF Resistors
Leftmost is the new dual-mono headphone amplifier, with extensive power supply decoupling for lowest noise, including C0G Capacitors.
Again, MELF resistors are used for the audio functions.
As you can gather by now, we don’t use inexpensive parts and to give you some idea of the lengths we go to, we will upload some internal pics of the soon to be launched 777 Signature Edition as they are also used there too.
