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After excellent feedback (thanks!) and some testing, I decided to add more detail and remove any recollections or suppositions that were not repeatable, to try and give a better picture to work with. I apologize for those who have answered given insufficient or inaccurate information!

Cooler Side

I have a chest freezer and a penguin glycol chiller on one outlet, with several Inkbird temperature controllers. One keeps the chest freezer at beer temps (~40F, set to 39F with +/-1 OD/HD), the other two control pumps for the chiller, and heat pads to keep fermenters at a given temp, which ranges depending on style and recipe. These all are connected to a fairly inexpensive Triplite power strip and surge protector.

Entertainment side

On the other plug of the same outlet, I have an APC power saving surge protector. This has a "master" which is split between a TV and PC, so when either power on, the sound system plugged into the "Controlled by master" powers on, and vice versa. The sound system consists of a Sony STR-DH550 with two input connections (coaxial digital from the PC and optical digital from the TV). The receiver's connected to a stereo sound bar, a center speaker, two surround speakers and a powered subwoofer (a Mackie Thump 15).

Momentary Sound Pause

The issue occurs when I'm listening to music from the PC (coaxial s/pdif) and the chest freezer powers off, there is a momentary pause in the sound, every time. Per comments, I tried listening to audio from the TV (toslink optical s/pdif) and could not repeat the outage. I will leave this up today to monitor it further.

In testing, the chiller has not impacted the audio, manually switching on or off or when it automatically switches on (high temp) or off (reaches low temp) and the chest freezer did not impact audio powering on.

Plugging the cooler side into a different circuit

I ran a long extension cable to the other side of the basement and plugged the cooler side into it. There is no pause in audio when connected there.

Solution

I have two toslink connectors on the receiver and both toslink and coaxial s/pdif on the PC. I switched this over and have not seen a glitch all day! Thanks @Jasen

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    A UPS would help and maybe completely cure your issue....just an opinion, not sure, all you can do is try it. Or that, if possible move the fridges to another circuit. Apr 20, 2023 at 15:39
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    Before investing in a UPS, grab a long extension lead & plug the hifi [or fridges depending on convenience] into another circuit. It might be RFI rather than voltage drop. My iron did the same on my cable box for the TV. New iron & separate circuit later… I learned to live with it. I've got all the usual RFI protection on everything, it just still does it. We just watch something pre-recorded on it now when we iron, which isn't affected.
    – Tetsujin
    Apr 20, 2023 at 15:50
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    Power 'smoothing' would be first thing at a reasonable price. Such as whathifi.com/tacima/cs947/review After that what you really need is voltage stabilisation, not UPS. The trouble is, you're then into the esoteric 'audiophool' market & people will charge what they can bleed from you.
    – Tetsujin
    Apr 20, 2023 at 16:09
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    what sort of sound system. maybe switch to optical cables?
    – Jasen
    Apr 21, 2023 at 0:15
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    I’m voting to close this question because it's not about DIY Home Improvement.
    – brhans
    Apr 23, 2023 at 20:25

4 Answers 4

1

Try optical cables instead of using RCA, this could be a ground loop interrupting the digital music signal.

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When a motor comes on, it draws a large amount of current (Locked Rotor Amperage). Depending on the quality of the wiring on the circuit, this can lower voltage somewhat, annoying other appliances.

However, when a motor turns off, motors are inductors. They resist changes in current just like capacitors resist changes in voltage. The motor will increase the voltage until something "gives" - typically insulation breakdown in the motor or wiring to the motor. In a perfect world, the builder puts a MOV across the motor leads, so it acts like an overrunning diode on a DC inductor. However, MOVs do wear.

So with your problem happening at motor shutoff, it sounds to me like your root problem is not a brownout, but a voltage spike. Thus, anti-brownout/blackout strategies like UPS's are not going to work here.

The root problem is a surge, I like solving surges at the source, so I would use a plug-in surge suppressor on the refrigerator's plug, or a hardwired surge suppressor near the refrigerator's terminals. In a perfect world you identify what on-board surge suppression the fridge has, and repair it.

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  • Interesting. Would the fact that I have surge protectors on the chillers and the audio equipment mean they aren't sufficient?
    – Wyrmwood
    Apr 20, 2023 at 22:24
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    @Wyrmwood or worn out. Surge protectors are ablative, they get consumed. Apr 20, 2023 at 22:33
  • As it is the temperature controller cutting power to the chest freezer, I'm wondering if this is somehow bypassing the on-board surge suppression? It's a really cheap chest freezer too.
    – Wyrmwood
    Apr 21, 2023 at 13:49
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A UPS is a good idea. I use one on my home theater to alieviate issues from short blackouts.

One thing to consider is that high-end amplifiers can have numerous protection circuits built in for, among other things, protecting your speakers from abnormal ouput. This does make them more sensitive and can cause the output relay to open for a programmed time delay, even if the input circuitry is still on and working.

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  • So the momentary pause in audio may be the receiver doing it's job to protect the speakers?
    – Wyrmwood
    Apr 20, 2023 at 17:10
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    Exactly. Your other appliances and even the receiver display might stay on, but it's dropping the amplifier load as a self protection feature. Apr 20, 2023 at 17:12
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    For pro sound, what's often used is a "power conditioner" -- which can be thought of as a "continuous " (as opposed to switching) UPS with a battery only intended to last a few minutes, which serves to hold the voltage at the correct level even if the incoming supply is far out of spec. I know of one venue where wall power dropped to 90V on a regular basis; that may have been fixed since then.
    – keshlam
    Apr 20, 2023 at 18:19
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I would suggest a UPS. There are many types of UPSs

  • For surges
  • For brownouts
  • For power outage

You need to get one for brownouts.

Even though a surge protector won't help with this issue, you should have one to protect your amp.

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