Those two FETs at Q15 have to go. They do degrade the audio a tad and can go "leaky" reducing the output level. Sometimes they short completely and the channel is dead!
I removed the FETs and put a relay there instead. Much better.
I used a 5V DC low current relay with the coil tied to ground through a 17V Zener diode. The other side of the coil goes to the output pin of the comparator.
After 5 seconds or so, the output pin of the comparator goes to -23V, AND THE RELAY CLOSES. At 5/6 volts across the coil the relay current is only 11 milliamperes, easy for the comparator to handle, and low dissipation for the Zener diode (0.190 W. with a 0.500 W rating).. The contacts short the output to audio ground, the same way the original FETs did, with MORE attenuation, and less distortion and loss. Use a diode across the coil in reverse bias, for the coil current release transient.
I removed the FETs and put a relay there instead. Much better.
I used a 5V DC low current relay with the coil tied to ground through a 17V Zener diode. The other side of the coil goes to the output pin of the comparator.
After 5 seconds or so, the output pin of the comparator goes to -23V, AND THE RELAY CLOSES. At 5/6 volts across the coil the relay current is only 11 milliamperes, easy for the comparator to handle, and low dissipation for the Zener diode (0.190 W. with a 0.500 W rating).. The contacts short the output to audio ground, the same way the original FETs did, with MORE attenuation, and less distortion and loss. Use a diode across the coil in reverse bias, for the coil current release transient.
