QS 867 Rev A with speaker 'hiss'

[Jacques]

I've noticed my QS boots with a nice quiet internal speaker but after anything trigger an audio sounds in OS 9.2.2 or OSX  I start getting a hiss, like a static sound. Another user had the same issue but I cannot see if there was any resolution to this. https://macos9lives.com/smforum/index.php?topic=6444.0

As soon as I plug in a set of headphones / lineout to to rear the hiss stops...there is no hiss on the external speakers.

I can often try and play with the volume slider and make the hiss disappear, but not very frequently. A reboot will silence things again. I cleaned the mainboard when I first got the machine, checked connections, nothings seems out of place. The speaker dome is slightly indented but I suspect a lot of QS speakers are like that.

Any ideas?

Thank you.

[aBc]

First idea here would be to check and clean the connection / connector from the speaker to the mobo
(As it doesn't really occur until you place some different demand upon it, until after the initial boot.)
AND you might PM @Borgmac - to see if he ever did solve his hiss problem.
And that thread you noted, also has other useful possibilities to try.