I bought a Taranis X9D and quickly learned that there is a weak speaker in the transmitter. After searching I found that most people pop the case open and remove the old speaker. In place they add a 36mm speaker.
There are many versions of the speaker adapter that can be found here on Thingiverse. At the time the site was down so I went ahead and made my own.
Here is the link to the speakers that I purchased.
This is as easy as swapping wires and using this adapter. I was very meticulous on the placement and depth. I ended up using hot glue and mounting the speaker to the adapter before mounting to the transmitter.
Worked as it should and I am more than pleased.
This is an original design.