Here's my idea of a portable headphone amplifier.
A line receiver INA1650 (instrumentation amplifier with all its benefits) that feed two LM4880 that drive the headphones (with separate volume control.)
The power supply would be a split +-2.85V, just below the maximum 6V allowed by the LM4880.
Now my doubts are:
- The INA1650 requires a minimum of +-2.25V to work, would 2.85V be too little to make it work well?
- According to the typical application 8.2.5 (INA1650) it has on the tip and ring traces a 100K resistor to ground. Are they really needed? Wouldn't the 500k resistors at the input pins in the chip itself be enough?
- Is the Cb capacitor still needed at the bypass pin when using the LM4880 with a split supply? 4 I need the total current draw in order to know if the voltage regulator I choose is good enough for the circuit. For each LM4880 ~0.09 A (250mW @ 5.7V per channel) and about 100mA for the INA. Would that be around 300mA for the whole circuit?
