If you have one of those usb sound cards (even cheap $5 will do) - try to feed the sound through one of them. If that helps, like it helped me - it is probably caused by fluctuating power supply when your cron job runs.
In my case, disk or network activity will cause it. On thinkpad, it is also caused by external mouse movements. My solution is combination of usb sound dongle and selective hearing. Hope it helps, Tomas On Wed, Mar 25, 2020, 08:52 Michael Barnes <barnmich...@gmail.com> wrote: > On Wed, Mar 25, 2020 at 8:17 AM Galen Seitz <gal...@seitzassoc.com> wrote: > > > On 3/24/20 10:23 PM, Michael Barnes wrote: > > > Not really Linux related, but very strange. I have a real nice set of > > Altec > > > Lansing computer speakers hooked up to one of my Linux Mint machines. > > This > > > is a three piece set with two desktop speakers and a large subwoofer on > > the > > > floor. > > > > Model number? > > > > > I've had these speakers for at least ten years and they have always > > > worked and sounded good. I hooked them up to this computer about a > month > > > ago. After a couple weeks, they started making a very loud low > frequency > > > beep/buzz every thirty minutes. > > > > Can you tell if the noise is only coming from the subwoofer? > > > > > It is about a one second burst. I turned > > > them off with the on/off switch on the volume control, and the beep > > > persisted. > > > > So with the switch in the off position, the noise continues? I agree, > > that's very odd. That suggests that the switch is only switching the > > audio input, not the power. > > > > > At exactly :29 and :59. I unplugged the audio input from the > > > computer speaker jack and the beep continued. > > > > As suggested earlier, it could be RFI, but given what you've described, > > I'm leaning towards a failing power supply. > > > > > There is no kind of logic > > > circuitry in this thing. Just an audio amplifier and related > electronics. > > > The only way to stop it is to unplug it. When plugged in it is like > > > clockwork at exactly :29 and :59, regardless of whether it is connected > > to > > > the computer or not. I hooked up another set of speakers to the > computer > > > and they do not do this. Sad, because these are a great sounding set of > > > speakers. > > > > If the speakers were working, but now, without any changes, they have > > started generating noise, I think a cap in the power supply may be > > failing, allowing power line noise to come through. It could also be a > > cap in the audio path that is failing, allowing RFI to get into the > > audio. Please post the model number so we can see how they are wired, > > and where the power comes from. > > > > Please confirm that you haven't introduced anything new to your home > > environment (new appliances, etc.) that might be coincident with the > > noise appearing. > > > > galen > > -- > > Galen Seitz > > > > Model is VS-2121. The sound is not random. It happens at exactly :29 and > :59. It is not quiet, either. We can hear it pretty much throughout the > house, so it's not like something that has been there all along and just > wasn't heard over ambient noise. It is more of a sound than noise, a low > frequency rumble, but not like static type noise as you would get from AC > hum or failing components. More like hitting the bottom note or bass pedal > on a keyboard (musical keyboard, not computer keyboard). I'm not sure of > whether it is coming from all speakers or just the sub-woofer, as I have > not been at the computer when it happens. The computer is in my wife's > hobby room. It is not used that much, only for email and occasional web > surfing. Interesting that the on/off switch doesn't really turn it off. As > I plug/unplug it, the subwoofer pops. > > Thanks for everyone's comments. > > Michael > _______________________________________________ > PLUG mailing list > PLUG@pdxlinux.org > http://lists.pdxlinux.org/mailman/listinfo/plug > _______________________________________________ PLUG mailing list PLUG@pdxlinux.org http://lists.pdxlinux.org/mailman/listinfo/plug