Speakerphat cracking noise


I have a Pi0W 1.3 with a standard Stretch O/S. Headless.
I installed the PHAT software with curl -sS https://get.pimoroni.com/speakerphat | bash
On bootup, the speaker makes 3 sets of double (1s apart) cracks at (approx.) 30s, 1m and 2m in.
Then it stays silent.
I then run espeak and approx. 18s after it finishes speaking I get a double crack from the speaker (about 1s apart).
I have seen other threads regarding this, but I don’t see a solution - or if there is, I don’t understand it!
I have looked in :
and found :
load-module module-suspend-on-idle timeout = 604800
I assume this has something to do with it? Although I commented it out and rebooted and still have the same issue…
Can anyone assist please?