Ive read that you should tie the output of a preamp to a signal ground along with the input ground and lift that with 1ohm resistor from the psu ground. Im wondering if the same should apply to headphone amps. Because if low ground impedance and power transfer is priority, i feel that the output gnd should be tied to psu ground, much like a power amp.
Which is the better arrangement and why?
Which is the better arrangement and why?
There is a big difference in the earth return current noise from a normal loudspeaker power amplifier and the earth return current noise from a normal headphone amplifier ---there lies the difference.
I follow the same approach for headphone amps as I do for power amps: I use ground planes and copper pours to ensure the lowest ground impedance. I keep the sensitive grounds (signal ground) away from high ground currents (either by component placement or by the ground plane/pour design) and join the two at the ground connection at the output.
You can read my rationale here: Taming the LM3886 Chip Amplifier: Grounding – Neurochrome
Tom
You can read my rationale here: Taming the LM3886 Chip Amplifier: Grounding – Neurochrome
Tom
if everything is running Class A then ground return currents don't add nonlinear distortion, only inaudible crosstalk errors - and with headphones, even closed back have acoustic crosstalk in the -40 dB range
To start with, you might not need hum breaking resistors. Headphones amps being low power, it's easy to have power sources not requiring a earthed device.
In other cases, I'd follow the advices in this link : Ground Loops
In other cases, I'd follow the advices in this link : Ground Loops