Other Parts Discussed in Thread: NE5532, TPA6139A2, TPA6138A2
I'm trying to implement a pop-free circuit with the LM4880 that is connected to a 10 ohm headphone. I use the LM4880's shutdown pin to mute and unmute but I'm getting a lot of pop when the state of this pin is changed.
The circuit is composed of a DAC, the NE5532 (buffer) and the LM4880. The buffer is supplied with +/-5V and works with a band-pass filter through the decoupling capacitors (C45, C46, C52, C53, C55, C56). The LM4880 is powered with 5V and has inverted unity gain and a 330 uF output capacitor (CP3 and CP4) and 10 uF bypass capacitor.
- Changing the LM4880 bypass capacitor from 10 uF to 100 uF: no sigficant change
- Changing buffer DC decoupling capacitors (NE5532) from 22 uF to 1 uF: no significant change
- Changing the LM4880 bypass capacitor from 10 uF to 1 uF: no significant change is heard, just a change the output speed to archieve Vdd/2
- Removal of the 2 kohm stabilization resistors from the LM4880: there was no change
- Removed the capacitor from the mute circuit: there was no change
Any ideia how can I solve the problem?
Best regards.