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I have dedicated lines, but why is this happening?

When my central air kicks on, I hear a pop through each speaker.

Now the odd part is, I just started hearing this recently. I never remember hearing it for the first several months after I had the dedicated lines installed.

I have made several changes to my system recently that has taken the transparency of my system to a level I didn't think was possible, but I don't think that could explain why I am just now hearing the pops. Or could it?

But the primary question remains. Why is the air conditioning popping through my speakers when I have dedicated lines.

Could this be coming back through the main bus bar ground in my panel?

What would fix it?

I obviously know crap about this stuff.
fiddler
stehno
1,453 posts
 
I also agree that perhaps the AC is the culprit. Perhaps it's now drawing more current at startup.

But I would seriously doubt grounding is the issue.

-IMO
herman
2,284 posts
 
Dedicated does not mean isolated. Your dedicated lines are tied together with everything else at the power panel so it is very easy for noise generated by something like the AC unit to find it's way into your gear.
twl
3,251 posts
 
When an air conditioner cycles, there are relay contacts that are actuated. These relays commonly arc when they are actuating, whether opening or closing. The older they get, the more they arc. This arc throws wideband hash into the air and onto the power line. It is similar to a small arc-weld. This is very likely to be the culprit. You probably need better RFI/EMI protection/filtering in your system.
gs5556
1,249 posts
 
Two things you can check:

The central ac unit may have a problem such as a faulty compressor (overheats?), pull-in contacts, loose wiring on the motor, loose wiring in the circuit (wire nuts, j-boxes, etc), loose fan belt on the blower, or a bad low-voltage transformer. I would bet on the contacts that pull in the blower line voltage.

The work done by the electrician. Each circuit have its own neutral home-run? Sometimes they'll cheat by grabbing the nearest white wire. Big no-no.

All motors cause transients and surges in your house power system. The above can make it worse, in terms of hearing the noise in your gear. If everything checks out ok (including your gear), then you may look into getting a whole-house surge suppressor (TVSS) installed in your main panel. I also agree it ain't a grounding issue and that dedicated circuits are not the cure-all for power problems.
albertporter's avatar
albertporter
4,949 posts
 
I resolved this problem at the source of noise in my home. I filter the AC blower, AC compressor, microwave oven, all three computers, the refrigerator and every other device that causes me misery.

Expensive you say? Not at all. You can buy good filters for each of the above items for less than one audiophile device.

More importantly these don’t degrade the performance of your sound system. Stopping the noise from entering your stereo is much easier than trying to remove it once it’s already there.

Here is the company I bought my suppressors from:
http://www.elect-spec-transformer.com/about.htm
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