<https://www.concertina.net/forums/index.php?/topic/25517-duet-playing-practice-question/#comment-223098>
<http://schema.org/text>
"The same volume controlling effect can be achieved by installing o-rings in pad holes. I have regulated my two lowest basses this way after first drilling maximum diameter holes. Even 0.5mm ring made measurable difference. And since those can be friction mounted, it’s perfectly reversible while not changing button travel.\n \n"
<https://www.concertina.net/forums/index.php?/topic/25517-duet-playing-practice-question/#comment-223015>