I have this one that works fine.
https://smile.amazon.com/Rapco-Horizon-CVPBLOX-Control-Mute/dp/B003ML6N3C/ref=sr_1_6?crid=KIUEP8HKZSS3&keywords=mic+volume+control&qid=1575966989&sprefix=mic+volume%2Caps%2C160&sr=8-6
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pa4X 76 ,SX900, Audya 76,Yamaha S970 , vArranger, Hammond SK1, Ketron SD40, Centerpoint Space Station, Bose compact