I just grab the tar file from the original source (
https://github.com/thesofproject/sof-bin/releases). Then copy the sof-vXX and sof-tplg-vXX directories to /lib/firmware/intel, and symlink them to sof and sof-tplg (all in /lib/firmware/intel).
I'm currently on v1.8. Haven't tried v1.9 yet, but the tar file looks the same at a quick glance.