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Topic: Electrical panel relocation - potential source of noise for audio system? (Read 4125 times) previous topic - next topic
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Electrical panel relocation - potential source of noise for audio system?

[Note - I'm not quite sure this is the correct section; mods please move if appropriate]

How bad a potential hum/RFI problem is an home electrical panel right within a few feet of a Class D subwoofer amplifier?

We're doing some home upgrades. Unfortunately as part of these upgrades we must move our electrical panel. It currently sits in a stairwell, and that was unfortunately disallowed in a 2008 code revision. Even more unfortunately, the most practical location (i.e. doesn't involve cutting into a century-old plaster wall in a heavy-traffic room) is in the basement. Due to the HVACs vents in our unfinished basement restricting height in most locations to below the 6'6" required by code, placement is further limited. (Code requires a clear space zone that's 6'6" high, 30" wide, and 36" deep.)  Long story short, the electrician wants to put the panel in a spot in the basement - right where my subwoofer amp currently sits! 

The subwoofer amp is 4-channel touring/installation unit with SMPS and Class D output stages. The subwoofer amp and living room audio equipment share a 20A circuit, installed a few days after we closed on the house ca. 2014. The subwoofer amp is plugged into a Panamax 20A "power conditioner," because that was the lowest-effort way to effect a 12V trigger on the amp. The subwoofer amp connects to the DSP in the living room via an 8-channel balanced snake (Mogami 2932); four channels of the snake carry balanced audio, and one channel carries the 12V trigger signal. In any case, all of the electrical cables to current wiring would have to pass by the snake and subwoofer speaker wiring.

I can move the subwoofer amp to be perpendicular to the proposed panel location and about 5' away in a straight line.

Am I stressing out about a likely non-issue, or should I do whatever I can to find an alternate location for the panel?.

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #1 –
You might be stressing out over nothing.  Honestly, you'll have to wait until it's installed.  I be more worried about having access to the panel anyway.  It's up to you, it is your house, so if it really bothers you can ask about where else to put the panel.

Building codes are there for a reason.  Maybe too many people got killed on the stairs or it was because of too many fires and they changed the code as a result.

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #2 –
Quote from: jbhaider on
[Note - I'm not quite sure this is the correct section; mods please move if appropriate]

How bad a potential hum/RFI problem is an home electrical panel right within a few feet of a Class D subwoofer amplifier?''

Why should there be any at all?

Quote
We're doing some home upgrades. Unfortunately as part of these upgrades we must move our electrical panel. It currently sits in a stairwell, and that was unfortunately disallowed in a 2008 code revision. Even more unfortunately, the most practical location (i.e. doesn't involve cutting into a century-old plaster wall in a heavy-traffic room) is in the basement. Due to the HVACs vents in our unfinished basement restricting height in most locations to below the 6'6" required by code, placement is further limited. (Code requires a clear space zone that's 6'6" high, 30" wide, and 36" deep.)  Long story short, the electrician wants to put the panel in a spot in the basement - right where my subwoofer amp currently sits! 

The subwoofer amp is 4-channel touring/installation unit with SMPS and Class D output stages. The subwoofer amp and living room audio equipment share a 20A circuit, installed a few days after we closed on the house ca. 2014. The subwoofer amp is plugged into a Panamax 20A "power conditioner," because that was the lowest-effort way to effect a 12V trigger on the amp. The subwoofer amp connects to the DSP in the living room via an 8-channel balanced snake (Mogami 2932); four channels of the snake carry balanced audio, and one channel carries the 12V trigger signal. In any case, all of the electrical cables to current wiring would have to pass by the snake and subwoofer speaker wiring.

I can move the subwoofer amp to be perpendicular to the proposed panel location and about 5' away in a straight line.

Am I stressing out about a likely non-issue, or should I do whatever I can to find an alternate location for the panel?.
[/quote

Yes,]

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #3 –
The only thing I wouldn't like is an electric panel that made any bit of an audible hum/buzz.  However that might be indicative of electrical problems that need addressing before the fire department has to be called to put out an electrical fire.

I went to a school where this one circuit panel in the hallway was always buzzing.  They never fixed the damn thing and to my knowledge is probably still doing it to this day.

I have a UPS for my computer by a subwoofer and I have no problems with either device being by each other.  The UPS keeps taking the rumbles just fine and the subwoofer isn't distorted at all.  My problem is limited under the desk space.

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #4 –
Quote from: Chibisteven on
The only thing I wouldn't like is an electric panel that made any bit of an audible hum/buzz.  However that might be indicative of electrical problems that need addressing before the fire department has to be called to put out an electrical fire.

I went to a school where this one circuit panel in the hallway was always buzzing.  They never fixed the damn thing and to my knowledge is probably still doing it to this day.

I have a UPS for my computer by a subwoofer and I have no problems with either device being by each other.  The UPS keeps taking the rumbles just fine and the subwoofer isn't distorted at all.  My problem is limited under the desk space.


You've got two cases here where the electrical maelstrom inside the box (switchmode amp and UPS) dwarfs anything that might be induced at even a relatively short distance from an electrical panel in a heavy metal (usually ferrous) box.

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #5 –
Thanks for the reassurance, gentlemen.

The "unfortunate" part of the code change is simply that it's going to cause additional expense to the renovation.

I have no specific reason to fear a problem, beyond noisephobia and general fear of touching anything that theoretically could cause more of it. And the "no question is too stupid to ask [as long as you're willing to actually accept counsel, or at least engage it in good faith]" theory.

There is already one known noise gremlin in this house: the TV is on the same circuit as the thermostat, and there's a ground loop currently mitigated with a cheater plug on the TV. (Too bad HDMI isn't optical.) Thankfully we're on fiber instead of cable now; the cable installation also caused hum, requiring an isolation transformer.

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #6 –
Quote from: jbhaider on
Thanks for the reassurance, gentlemen.

The "unfortunate" part of the code change is simply that it's going to cause additional expense to the renovation.

I have no specific reason to fear a problem, beyond noisephobia and general fear of touching anything that theoretically could cause more of it. And the "no question is too stupid to ask [as long as you're willing to actually accept counsel, or at least engage it in good faith]" theory.

There is already one known noise gremlin in this house: the TV is on the same circuit as the thermostat, and there's a ground loop currently mitigated with a cheater plug on the TV. (Too bad HDMI isn't optical.) Thankfully we're on fiber instead of cable now; the cable installation also caused hum, requiring an isolation transformer.
I expect your isolation transformer was a 120V unit feeding the TV. A far less intrusive fix would be a "galvanic isolator"  in the RF cable - essentially an RF isolation transformer. I've had far more problems with RF cables whether antenna or cable company as it's very easy and likely to tie together "grounds" from various circuits around the house as the TVs and PCs in different rooms are on different breakers but more importantly, different neutrals. This is not broken or a "hazard". People often assume Voltage drops on various circuits but ignore the equivalent "drop" - actually a "rise" on the neutral depending on branch load currents. Thinking about it, I'm surprised an RF isolator is not mandated in each device as it would be a very inexpensive fix to a host of vexing problems. Good isolators are available from various sources for less than $10.

As for your class D amp near a power box, I would expect zero issues as Arnold pointed out.

G²
 

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #7 –
Quote from: jbhaider on

There is already one known noise gremlin in this house: the TV is on the same circuit as the thermostat, and there's a ground loop currently mitigated with a cheater plug on the TV. (Too bad HDMI isn't optical.) Thankfully we're on fiber instead of cable now; the cable installation also caused hum, requiring an isolation transformer.

Cheater plugs might be used for diagnostic purposes, but for consumer end-use they are a safety no-no.

Galvanic isolation of HDMI is possible using CAT-5 cable based line extenders, with really short CAT-5 cables.

It is often possible to reconfigure the system too keep  video completely out of the audio section, and use TOSLink for isolation to address any remaining issues.

USB galvanic isolators are cheap enough if you don't let yourself be defrauded by people who say theirs "Sound the best" ;-)

Audio isolation transformers are probably the most expensive alternative. Beware because some are very good, and others are pretty horrible, and they may all cost about the same and look about the same.

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #8 –
Quote from: Glenn Gundlach on
I expect your isolation transformer was a 120V unit feeding the TV. A far less intrusive fix would be a "galvanic isolator"  in the RF cable - essentially an RF isolation transformer.

Maybe I used the wrong term. Back when Comcast had a monopoly on modern internet at my address, this is the device I used to to keep cable noise out:
https://www.amazon.com/gp/product/B0070Q6URO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Fortunately we have two fiber providers now.

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #9 –
Quote from: Arnold B. Krueger on
Cheater plugs might be used for diagnostic purposes, but for consumer end-use they are a safety no-no.

Agreed, though ours has been in use for about 2 years. TV is wall-mounted above the fireplace mantel. But since we're getting significant electrical work done, I've already asked the electrician to move that outlet to the audio circuit. There's good access from the basement, so it didn't add material expense.

Quote from: Arnold B. Krueger on
Galvanic isolation of HDMI is possible using CAT-5 cable based line extenders, with really short CAT-5 cables.

That's not my experience. Now we have a physical HDMI cable run through conduit in the crawlspace under the living room, but my first installer suggested "futureproof" HDbaseT. We went through baluns from Ethereal, Wyrestorm, and Binary/SnapAV. All had intermittent dropouts, even when running a known-good Cat6 above ground directly from one to the other.

Unfortunately Monoprice hadn't released their reasonably-priced fiber HDMI when I had the cable run.

Quote from: Arnold B. Krueger on
USB galvanic isolators are cheap enough if you don't let yourself be defrauded by people who say theirs "Sound the best" ;-)

Wait - you mean that new wave of audiophool USB products actually do something? I just thought they were this decade's Shakti Stones.

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #10 –
Quote from: jbhaider on

Maybe I used the wrong term. Back when Comcast had a monopoly on modern internet at my address, this is the device I used to to keep cable noise out:
https://www.amazon.com/gp/product/B0070Q6URO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Fortunately we have two fiber providers now.
That would be the gadget. RMS communication has the same unit for less than half that.

Welcome to the world of ground loops. They can be danged tricky to fix but you're on the right track.

G²

Re: Electrical panel relocation - potential source of noise for audio system?

Reply #11 –
Quote from: Glenn Gundlach on
Quote from: jbhaider on

Maybe I used the wrong term. Back when Comcast had a monopoly on modern internet at my address, this is the device I used to to keep cable noise out:
https://www.amazon.com/gp/product/B0070Q6URO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Fortunately we have two fiber providers now.
That would be the gadget. RMS communication has the same unit for less than half that.

Welcome to the world of ground loops. They can be danged tricky to fix but you're on the right track.

G²
\

FYI they are less than $3 on eBay, direct shipped from some place on the Pacific Rim.