Bad audio from analog_bridge


Hi all,
I trying to broadcast our club bm tg to broadcastify.  I installed mmdvm_bridge, analog_bridge and md380-emu as I don’t have ambe dongle.  I’m monitoring the audio output with nc -l -u -p 32001 | play -t s16 -r 8k -c 1 - 
I heard the voice correctly but there is a background noise kinda a pulse, I tried playing with gain but no luck, is someone can help with this?

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