Do your lights dim when your amp powers up?

Even modest power amps can draw a lot on startup.  If your lights remained dim after that I’d say you have an issue.  Now, is it bad sounding?  Of all the gear we use, linear amplifiers are more susceptible to AC voltage changes due to using unregulated supplies.  If it drops but comes back up you are fine.

To be clear, part of what has happened is your own fault here.  With 10 gauge wiring your startup current is going to be unusually high, so may affect the other circuits on the same leg for a moment.  You probably wouldn’t have this problem on a normal 12 or 14 gauge circuit! :D 

If in doubt the first step is to monitor how bad the issue is.  Get a cheap tester like this one and plug it into your outlet at your stereo and also at another circuit which shares the same phase.  See how bad the drop is, and especially measure the N-E voltage.  If you find an excessive drop, or more than 2V on N-E it’s time to contact an electrician.

On a related note, my home suffers seasonal + episodic voltage swings due to weather and HVAC turning on and off, as well as different voltages during the day vs. at night.  All within spec but to keep my system voltage regulated I use a furman with the AR + SMP features.   To be clear, don't fix house wiring problems with a power conditioner.    Only if you know your power is good/safe should you use a conditioner to improve the stability. 

Also related, I moved in when this house was about 15 years old and I did have flickering lights when certain appliances were used.  Like, my living room lights would flicker when the bathroom fan was on but on different circuits.  Little things like that all around the house.  I ended up replacing 100% of the wall switches and all the 120V breakers which fixed the problem.  My point is just that at 15 years, you start edging into breaker reliability issues, though they should overall last another 20 years.  If you end up replacing, get an in-panel surge protector as well. 

I don't see how tightening screws would do anything to reduce such in-rush current so I would not bother doing that.  

That's exactly right, while it may be good to make sure your screws are all tight, in this case you would be INCREASING current delivery.  I've seen this happen before ages ago.  

The lack of resistance in the 10 gauge wiring is INCREASING the inrush current and dropping the voltage at the panel until that current is reduced.   A loose outlet screw (unsafe!) or 12 gauge/14 gauge wiring would all increase the R slightly and REDUCE the inrush current. 

Some amplifiers (Luxman for instance) include a slow turn-on circuit, which limits the inrush current during startup, then gets out of the way, but they are uncommon. This circuit introduces significant resistance in the AC until the large power supply filters are charged up and then shorts out of the circuit when the idle current has stabilized. 

My fridge motor going on makes the lights dim for a second, but not my hi-fi.... 

Thanks for the information, helpful to me in understanding what’s going on.  The lights in my listening room are a set of six ceiling cans with fairly high wattage bulbs on a separate circuit from the sound system, and supplied by 14 gauge wiring on a 15amp breaker.  Based on the discussion here so far, I am thinking the 20amp/10 gauge “pipe” supplying the amp is the path of least resistance, and robbing current from the lights when the caps charge coming off of standby, resulting in a very brief dimming. Not sure if the difference in gauge of the wiring makes that big of a difference in the amount of observed dimming, but I guess it’s possible. An easy test is to plug the amp into a different circuit that has a higher gauge supply wire and smaller amp breaker and see if the lights dim as badly. That would require a very long extension cord.

I will say that I have tried different amps and other components in other rooms in my home without dedicated lines, and even with headphones that remove room variables, everything sounds better on the dedicated line and the difference is not that subtle.  I can put up with lights going down briefly on start up if it means the amp is winning the war for current!  The amp I looking to buy is more powerful than this, so I guess I will just have to get used to it.

kn

Hi , I had similar problems in my 40 year old house. 2 years ago I added Solar and during the process I had a brand new panel installed. Prior to that I had an issue where my pool motor ( single speed at the time ) was not running smoothly. The issue was a WEAK breaker that wouldn’t hold the current. While replacing it , I noticed the bus bar was pitted and moved it to a new location, problem solved. I also TIGHTENED all the connections. Now with a new box and a variable speed motor no issues. I just had the kitchen remodeled a few months ago and we did all new kitchen wiring for all new appliances. We went to a large induction stove that requires a 50 amp circuit. We went 6 gauge and it’s rated for 60 amps but has a 50 amp breaker. When we kick it on high , turn on the vacuum or use the tea pot I get a very slight startup flicker in other lights. Like mentioned above if is just a fraction of a second don’t worry. As mentioned above i strongly urge you to check for loose screws/nuts at the panel and check for tired breakers as they are cheap to replace. Regards, Mike B.