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Dedicated Power Line Project

I’m going to be adding a dedicated AC line to feed my audio system. Currently, the system is fed by a 75 foot run of 14 gauge romex that is likely daisy chained a few times in the wall between outlets. Needless to say when I turn the volume up, dynamics suffer and the overall sound quality is much less than I know my system is capable of. At louder volumes, bass notes will make the lamps dim and if I go louder, it seems like the system struggles and the bass notes get rounded off or sound “fuzzy.” My calculations tell me that with 75 feet of 14g romex, the voltage at the end of the line could be dropping by 5-10 volts, maybe more, during transient peaks. What I think is happening is that the power amps’ power supply caps are draining and there isn’t enough current to recharge them quickly enough and the amps start to draw directly from the AC line which causes a large voltage drop. 

Initially I was looking at a 10 gauge or 12 gauge line with a 20 amp breaker. After running the numbers, even a 10 gauge run could see some significant voltage sag at 75 feet during transients. At that point I considered 8 gauge, but the problem with that is that no electrical outlets will accept anything larger than 10 gauge, so I’ll have to do something fancy like place a junction box and step down to 10 gauge at the breaker panel and just before the outlet. Then I thought if I’m going to that much trouble with an 8 gauge, why not run 6 gauge? My calcs tell me 6 gauge could have a volt or two less variance than an 8 gauge and it wouldn’t be much more cost. So as of now, the plan is to run a 6/2 solid core romex line and run all the equipment of that. (I could run another line for the front end in the future but that isn’t the plan right now).  I have a few questions if anyone would be so kind to reply:

1) Are there any foreseeable issues with running “too large” a power line? I’m not sure if it’s accurate, but I’ve heard that large gauge is good for bass and small gauge is good for treble. Since I’ll be running everything (including the low current draw components like sources, preamps, etc) off this one line, is there any chance I’ll change the sound signature in a negative way?

2) What is better? In-wall romex or THHN inside a grounded conduit? I’m leaning towards romex because my gut tells me having the wire surrounded by something could hinder transients or hurt clarity but I’m not sure that’s accurate - that may just be from my personal experience with low level signal cables where too much insulation can be a bad thing. 
3) Are there any other “gotchas” that you can think of?

I’ve read the MSB Technology article and I’m subscribing to that theory which is this in a nutshell:

“It is the subject and goal of this paper. The gauge of the wire is FAR MORE IMPORTANT than the fact that the line is “dedicated”. The subject of this paper works on the theory that the varying musical demands of your amplifier are actually modulating the incoming power line, divorced from the utility (power company) by some resistance (12 or 14 gauge wall wiring at some length from the breaker panel has too much resistance for audio purposes).”

Thank you and wish me luck!
mkgus

Showing 11 responses by mkgus

mkgus's avatar
mkgus OP
324 posts
 
I was confused by that too. It didn’t help that I found an online Lowe’s listing for 8 gauge solid core Romex. It was an error: 8 and larger seem to be only sold as stranded.

I am not familiar with the code. I know I’ve seen 12 gauge and 14 gauge wiring used in a number of houses and in many cases, have seen one breaker turn off outlets AND lights. Perhaps codes vary or some houses just aren’t up to code.
mkgus's avatar
mkgus OP
324 posts
 
Thank you for your help, Miller and Cleeds! I’ve had the same thought about eliminating as many connections as possible and trying to avoid any junction boxes and pigtails. Maybe I can find a specialty outlet or make an electrically safe modification so I can avoid connections. Surely copper atoms chemically bonded to each other (pure wire) is better than any mechanical connection. I will likely start with one dedicated line and go from there with additional lines in the future if that makes sense. Fortunately the path I’ll take is mostly unfinished or in-wall spaces so I can add future lines easily. I’m curious to know the benefits of dedicated lines for each piece of equipment assuming the gauge is large enough so voltage drop is irrelevant. I’m thinking it has to do with each piece of equipment injecting noise into the AC wires so that if they’re on their own lines they won’t “talk” to each other.  
mkgus's avatar
mkgus OP
324 posts
 
Thank you for your reply. Very helpful!

Today I flipped off the breaker and started testing outlets to figure out everything that’s on the existing line. It’s worse than I thought. Included is at least 2 bedrooms and 1 bathroom which includes roughly 11 outlets, 3 light fixtures, a fan, and a bunch of switches. And who knows how many low quality 14 gauge daisy chain connections the power goes through before reaching the amps and other gear. No wonder I’m not ecstatic with my sound!

The plan as of now is to run 2 dedicated lines, a 6 gauge and a 10 gauge, and terminate them in the same junction box so they can share a ground. The 6 gauge will be for the power amps and the 10 gauge for the front end. 
Millercarbon, if you would be ever so kind, please PM me the details of your power supply system. I probably won’t forgo a breaker at the moment, but I’m sure I can learn a lot from your large gauge setup if you’re . Thank you!
mkgus's avatar
mkgus OP
324 posts
 
Connections. I want to avoid as many as possible and of the ones I do have, make them as good as possible. A post above mentions using crimp style connectors with proper tools. If I don’t go that route, how about welding? I could overlap the large gauge with the small gauge (for making outlet connections) and weld them together. I’ve read that welding copper can change its chemical properties, but is it really that big of a deal? A 2” section of welded copper cannot hurt the sound that much when you consider its one piece of metal at that point and not even really a “connection,” right?
mkgus's avatar
mkgus OP
324 posts
 
You and me both. This is the strange world of audiophiles. Something about no compromises and becoming neurotic in the pursuit of the best sound. 
mkgus's avatar
mkgus OP
324 posts
 
Thanks for the tips. I agree with your assessment on stranded vs solid core. I’ve found solid core to be better in my system and use it for all signal and speaker wiring. I’m not sure of stranded’s effects on power wiring. You can get 8/2 and 6/2 romex in solid core. Might be a special order but they make it. I’m on the fence about speciality high $ wiring for dedicated line. It probably helps but how much? Is it worth going from $100 or so for a spool of generic romex vs. $1,000+ specialty stuff? 
mkgus's avatar
mkgus OP
324 posts
 
Here’s 6/2 solid core Romex:

https://www.lowes.com/pd/Southwire-Romex-SIMpull-6-2-Non-Metallic-Wire-By-the-Roll/3127529

You’re saying that building codes won’t allow it to be used?
mkgus's avatar
mkgus OP
324 posts
 
That’s just confusing. Under specification, it says solid and it shows a picture of solid core romex. 
mkgus's avatar
mkgus OP
324 posts
 
Yes, thanks for looking into that! That may change things. I’m not sure how I feel about stranded wire for dedicated lines. With interconnect and speaker cables, I’ve had the best luck with solid. I wonder if it’s the same story for power wiring. 
mkgus's avatar
mkgus OP
324 posts
 
Seeing as they don’t make the 6 or 8 gauge solid core romex I thought they did, I’ll probably just run 10 gauge, which keeps things really simple. Does anyone know what voltage drop is acceptable for a dedicated line? The NEC states 5% is allowed but we all know that wasn’t decided upon based on the delivery of power to audio systems while attempting to maximize sound quality. I’m coming up with almost 3 volts of drop, so the equipment would see 117 V when driven hard. Any issue with that or are modern amps designed to operate just fine with a bit of voltage sag?
mkgus's avatar
mkgus OP
324 posts
 
Thanks for sharing. Any issues with that set up or does it sound just fine?

What is the best way to run two dedicated circuits? If you use two separate runs of romex, how do you tie the grounds together? Can you use 10/3 romex for two dedicated hots and a shared neutral and ground? Is that even code? 😀
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