Dedicated power circuits
I’m having some electrical work done including a whole house
generator, surge suppressor, and a new panel box. I am also going to have two dedicated power lines run for my stereo. I’ve read a lot on here about how this is a really nice upgrade and would greatly appreciate any advice to help me along on my project. Right now the plan is two 20 amp circuits with 10 gauge wire. One for my amp and one for my preamp and sources. My equipment is a McIntosh MC 452, a C47 right now but a C22 in the future, Rega P8, Rose hifi 150b, McIntosh MR 74 tuner and Aerial 7t speakers. I’m also replacing my panel box with a new one. It’s a brand from a company that’s out of business and the quality and safety is suspect plus there are no new breakers available.
So starting with the breakers, then the wire and finally the receptacles what should I be looking for? The electrician that just left here is planning on the new panel being a Cutler Hammer brand. Any help would be greatly appreciated.
@kingrex Wrote:
I completely agree! That was one of the reason why I ran four dedicated 20 amp branch circuits for audio and not one. 😎 Mike |
Per post 1596 Ccomment 1. Yes, this is where I find metal encased inwall wire to be a benefit. It is very good at rejecting EMI from surrounding wiring. I know that is not the intent of your comment. But its the point that EMI radiation is a real issue. Mostly with EMI getting into signal or speaker cables. But I am cautious of it with branch circuit to branch circuit as well. I also find any isolation transformer has to be located strategically to not interfere with the equipment it is powering. That is why I prefer a wallmount in the adjacent room. Per comment 2. I do not find the sine wave distortion from audio equipment PS to be problematic if you run dedicated line. That is partly why I strongly recommend multiple circuits. I do not like a single branch with the assumption it is ridding ground loops. PS to PS noise can become an issue on a single branch carrying all the equipment. My comment about the issues being in the equipment itself is exactly that. For Example, a 4 year old set of $60K monoblocks with buzz at the tweeter. Owner gets the amps updated and all the buzz is gone. A brand new $22K phono stage with radio coming out the speakers. I insert 2 other phono stages and the radio is gone. I did a lot of other test to validate the issue was the phono stage. $15K SET tube amps with bench tested measured voltage bleeding from the PS to ground creating ground issues. I see gear itself with issues. Not the power feeding it. People don't want to believe their expensive purchases have defects. But that is many times where "Issue" are traced too. Updating your power is not about solving issues. Its all about extracting the maximum performance from what you have. If you have hum and buzz, its most likely the equipment, not the electrical supply. If you have a hazy veil, soft uncontrolled bass, fatiguing sibilance, it very well may be the electrical infrastructure. |
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I had a chance to do a fair amount of listening yesterday and truly believe this was a worthwhile upgrade. I have my amp on one line my preamp on one line and my sources on the other line. The sound seems cleaner with blacker backgrounds. My system has never sounded better. By the way all three lines are on the same leg. I’m not going to write a flowery review describing how much my sound has changed but it is significant. Thanks for all the help guiding me through this process, it’s greatly appreciated. |
@gphill 👍 Mike |
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Kingrex said;
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I’ve posted that on this forum in the past. I first read about it, here: An Overview of Audio System Grounding and Interfacing Look at the chart/picture on page 35. Note, Twisted L-N beat out all the others. The EGC is pulled in the conduit along side the twisted pair.
Best practices dictates a true dedicated branch circuit used for sensitive equipment does not share a conduit or cable assembly with other branch circuits.
NEC only requires one EGC sized for the largest circuit breaker handle amp rating of the circuits that share the same conduit.
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All the electrical work has been done and I have 3 new dedicated 20 amp circuits wired with mc 10 gauge wire and Hubbell 5362 outlets. The wire goes from the new outlets in my den, which is where I listen to music, directly to my new square d panel box with 20 amp arc breakers. I tried it out today and everything is working as it should. Today was just casual listening to my local NPR radio station, but I can report there were no hums or ground loops just very nice sound from my Mac MR 74 tuner. This week I should have some chances to listen a little more critically and will report how the sound of my stereo has changed.
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I feel there are many types of people out there. Some are very fixed on the numbers. They need to see measurements and they base their decisions on them. I started as an installer. I worked in the field and followed the plans. Later I became an owner and designed the plans, as well as installed them. My foundation is based more on what I find works, than what the numbers say. That does not mean I ignore or am ignorant to the numbers. I am aware of them, but I follow more closely what provides results in the field. Take for example the above readings with Oyaide. Not the best. But that installation was fantastic sounding. I don't know why the numbers were so high. But it radically changed the owners perception of how the infrastructure is installed and what/how to use the materials. It allowed such a better sensed of understanding of his equipment he removed some filtering products from his system. He later found other he preferred. I don't find the measurable performance characteristics of a wire as important as what is the wire. There are other facets of electrical infrastructure that are more impactful than what is the measured mV between the neutral and ground at the duplex. At least as far as a home audio system is concerned. If I were wiring a recording studio, I would probably have to re-evaluate my objectives. With a home audio system, I want the presentation quiet, fee of grain/veil and I want it to sound as natural and close to unamplified instruments as possible. That's my goal. Having said that, I do need to revisit metal encased wire. Either MC or in a steel pipe. I also need to revisit how I am twisting the wire. Do either of these result in any shift in tonality or noise I can hear. I have even thought about full immersion cryogenic treatment. Although a recent conversation with an audiophile I chat with frequently made me question what happens when that wire leaves the bath, then gets thrown around on a floor at a job site, manhandled and pulled into a pipe, then manipulated in the panel and box. Have I just cracked free and rearranged all the molecules that were altered in the freezing. And what about over time. There are some people saying the magic of cryo treatment goes away over time. That is why I prefer to find the orientation of the grain from the factory and work with that. If people want to use metal, go right ahead. It will probably work out just fine. Just for goodness sake, don't go from box to box with it. |
Interesting question. A little while back I had a project where I had to run 55 feet, 2 circuits in one pipe on the outside of a house. I spun the hot and neutral only on the 2 circuits and pulled the grounds loose in the pipe. I measured 0 mv between any of the neutral to grounds. I was quite surprised at this as I usually see maybe 5mv to 20mv. It has made me want to set up a test in my own system and measure whether it is best to leave the ground loose or twisted. I have also been told by a cable manufacturer to try and twist the ground backwards over the twisted hot and neutral. These are all things to consider.
Another project really surprised me when the Oyaide of about 20 foot runs was giving 72 plus mV between the ground and neutral. As of this time, I have not had anyone tell me they are experiencing hum issues from induced mV onto the ground. That is not where I end up tracing the issue out. I have had severe hum issues when someone uses MC and goes into one box, then leaves with MC to a second box and lands a second duplex. I have seen this issue twice. I have not seen a hum issue when this is done with NM wire. But I would never advise anyone do as such. There are times when people have budgets and want to shave costs. Even 10 AWG NM is expensive. Every run is about $350 to install if the walls are open. It adds up. I had another project very similar about 4 months ago. 2 full circuits on the outside of the house in 1 PVC pipe. About 50 foot run. My grain oriented twisted wire. The customer says the system is dead quiet. |
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Kingrex said:
You are the first person that has raised ground issues with MC cable, at least on the audio forums I follow. Could you expand on the problems you have experienced? If it is ground loops, it’s not the MC cable itself causing the ground problems. From what I have read is the audiophile that had MC cable installed are happy with the MC dedicated branch circuit(s). .
Where did that come from??? Not from my above post. 🤔
The subject matter of my post is about induced voltage by the magnetic fields generated by the Hot and Neutral current carrying conductors onto the EGC of the branch circuit wiring. Therein, NM cable vs MC cable. If you read the two Links I provided it is proven, by measurements, MC cable does a better job of preventing the magnetic fields generated by the current carrying Hot and Neutral conductors from inducing a voltage onto the EGC.
FYI, The bigger the connected load on the branch circuit conductors the bigger, the greater strength, of the magnetic fields. So it would stand to reason a big hungry power amp connected to one dedicated circuit would draw more current than say a CDP on another dedicated circuit. The EGC of the branch circuit with the power amp would be more susceptible to the chance of an induced voltage onto the EGC of an NM cable branch circuit that an MC cable branch circuit. (Especially long branch circuit runs). Therein with MC cable there would be less of chance of a difference of potential between the two EGCs of the two branch circuits than NM cable. YMMV...
The worst branch circuit wiring method would be to loosely pull conductors in a conduit. Worst yet is more than one dedicated circuit with conductors loosely pulled in the same conduit. Sure fired way to create ground loop hum problems. . |
AQ, Shunyata, Isoteck, Torus are all filters with their own technology. And Voice. I was pretty pissed when TAS did an article on power conditioners and failed to mention an isolation transformer. Isolation transformers are in most every recordijg studio around the world for 2 reasons. One they work. 2, Art kelm who specifies that work finds they work best and uses them. I like them as I have never heard one do negative things. Only positive. And I can feed any amp. I always am aware what any of the other filters are doing. If you hear noise out a speaker, that is ground or equipment issues. Its not dirty power. You deal with the issues in different ways. If you read Arts site, you will see he calls out metal wire and isolated grounds in his cable runs and associated panels. There are reasons to like metal. IMO, its not about geometry or performance. There are other reasons to like it. But the positives of metal can easily be overcome in NM when installed correctly with the rught materials. . And you don't end up with ground issues. NM reliably works. Filters are doing a job that addresses noise on the power line proper wiring or metal encased wire do nothing to address. |
PS - Most linear amplifiers use power supplies which are filtered but not regulated. That is, the DC voltage at the power rails is at the mercy of the incoming voltage. A long term change in the incoming VAC will be proportionately reflected in the VDC at the rails. All the low voltage gear (DAC, preamp, streamer, tuner, etc.) however is always filtered and regulated. A wide difference in the incoming VAC won’t affect the voltage that feeds the circuitry. |
When I ran my MC cable I used metal boxes for the outlets so that the MC cable jacket is attached to the metal outlet box and the metal case of the breaker box. I believe the metal casing of the breaker box is grounded. I did not know that the MC cable was twisted but I am glad to know that it is. Our neighborhood has underground utilities and I share a transformer with one neighbor. Our house is 23 years old. I brought home an AQ Niagara 5000 Power Conditioner from my local store (140 miles away) to try out. I did not take it back. Whatever magic is inside of it, it makes the sound better. Not sure if it has an Isolation transformer. The addition of good power cords improved the blackness of the sound as well. I have a vacuum tube preamp and I hear no noise with my ear to the tweeters. My phono preamp generates a little tube rush noise that can be heard close to the tweeters; but that is to be expected with 66 dB of gain. (Moving Coil preamp)
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Old White Paper. Middle Atlantic Products, Inc. https://cdn.cableorganizer.com/old-images/midatlantic/PowerSolutions-middle-atlantic.pdf ( Rev 2b 8/7/2007 ) . Newer white Paper. Middle Atlantic Products, Inc. Integrating Electronic Equipment and Power into Rack ...( Rev 4b 2002-2010 ) . Page 12:
. Again:
Read page 13. Look at the chart on page 13. Note the far right hand side of the chart. Arrow pointing up, Worst. Note where NM Cable is on the chart. Look at the numbers... Arrow pointing down, BEST. Note where MC Cable is on the chart. Look at the numbers... . Note the picture of the test board where the NM cable, (Romex) is fastened in place. Note the piece of cable is laying flat on the board. No twists, laying flat. Do you think when an electrician installs, say, 50ft to 75ft he takes care to make sure there is not any twists in the cable? Not hardly. Look at the picture of Romex, NM cable, on page 32. An Overview of Audio System Grounding and Interfacing Note:
What happens when the cable has twists ever so often along it’s entire length from the electrical panel to the wall outlet box? Do yo think the “null zone” exactly midway between line conductors is altered in any way? . / / / / An Overview of Audio System Grounding and Interfacing Read pages 31 thru 36. Look at the chart on page 35. Note Aluminum MC cable beats out NM cable. . FWIW, When I wired my dedicated 2 channel audio room in 2011 I ran two 75ft each of 10/2 NM cable. I followed best practices for the installation. 100% no twists? I doubt it. My system is dead quiet... . / / / / .
Yeah and more than likely the ground fault was at the cut off point of where the metal cladding was cut and removed for make up. Was the red insulator installed properly. Was the proper tool used for cutting the metal cladding for removal from the conductors. 3/8 in. Flexible Metal Conduit (FMC) Anti-Short
I’ve seen a steel staple buried in the sheath of NM cable, (Romex trade Name), and short out the cable. Don’t blame the cable. Blame the guy that drove the steel staple. .
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It’s not hard to make the comparison between 1 leg and 2 when you have gone through multiple systems and step by step made 1 change then listened. It makes a difference. And anyone that is caught up on just focusing on the phase line and voltage that is regulated by the equipment power supply is missing everything going on with the neutral and ground and how those 2 play into the system. Again, you can not hide from power line noise by selecting a phase. The noise is on the neutral. Unless the noise is from a 240 volt motor, in which case, it’s on both phase, so again you can not hide from it. Yes the power supply in the equipment regulates the incoming 120 volts to something else. But most equipment also has some connection of the equipment power supply of the signal ground that is tied to the chassis ground. So the signal is tied to the 120 volt power grid. I have heard it. Others have heard it. Just do it. In my opinion, there is no reason to not use 1 phase. There is 0 evidence only 1 phase causes any issues. So why fight it? To make a point? If that is the only reason you are arguing, your helping nothing. And, people here seem to think it’s great to put metal clad cable in and tie the ground to the shield of the cable which then allows the shield to become an antenna. Or at a minimum you have introduced a ground loop because the impedance of the shield and the copper wire are different. And before some "Engineer" gets on a rampage, let me say I have removed more than one annoyingly loud ground loop by eliminating 3 wire MC and replacing it with Romex.
I don't have an engineering degree, so I don't talk as technically proficient as others. What I have done is consult with many engineers, nuclear and NASA scientist. I have read a lot. I have taken specialized classes on grounding. I have made alterations, observed the result, then sought out knowledge from these type people to understand why I heard what I heard. I have also wired maybe 100 systems and have a large data base of evidence to back what works and what does not. I will say again, putting MC into an electrical supply is a receipt for disaster unless you are very cautious. IF you only ran 3 wire MC with a hot, neutral, ground and metal shield, you’re likely to have noise and/or ground issues. If you ran 4 wire and don't use an isolated duplex on even 1 outlet, you may introduce ground and noise issues. Even 4 wire MC is not a full proof way to eliminate noise. The jacket is an antenna for RF. It really does nothing for audio performance. Commercial facilities use metal for fire protection. Not because it has better performance characteristics. Just like your house has AFCI on all the breakers. They don't make your computer work faster or stereo sound better. To that matter, I have sat and listened with others and you can hear an AFCI breaker as a small veil on the music. They hinder audio playback. But they extinguish arc fires before they propagate to the rest of the house and burn the building down. They do a great job at that. As do metal raceways. I have been in a room when the switch was thrown and a faulty piece of MC arched inside the cable jacket. It was a very large boom and smoke smell. It took a while to find the fault as the case was fully intact. Just a small discoloration of the jacket under the flash. No flame left the jacket where it could ignite combustible materials around it. That is why you use metal jackets. It’s fantastic fire protection. The only shielding that blocks RF to any degree is a copper pipe. No one runs wire in copper pipe. Steel and aluminum don't really do anything towards blocking RF. They do block EMF. But cable management eliminates issues associated with EMF radiating from your power cable and contaminating other circuits in close proximity. That's all metal is doing for you. Maybe you want to run the rest of the house wiring that is in close proximity to your audio outlets in metal. That is a good solution. The only real block to RF is putting something such as a Torus Isolation transformer on your rack. The best location for a isolation transformer is on the rack. The second best is within 10 to 15 feet of the rack. After 40 feet, you have potentially lost much of the RF noise mitigation as it has reentered the circuit again. Metal won't keep it out. You can coat a room with Faraday shield. But it’s very hard to do correctly. I have heard of one audio room I want to visit and been in a commercial room that was RF treated. The one I was in was a government building where they wanted to house sensitive equipment. My phone still partly worked. It was very intermittent and definitely impacted it. But it was not 100%. I would like to get in the audio room with my RF sniffer and see what is still there. RF is an interesting phenomena. In my room, my meter reads about 1700 near my rack. Even with the equipment turned off. It’s not my audio equipment. Walk 24 feet out of the room and into my hallway and it reads about 70. It’s a massive drop in only a few feet. Directly above my audio room in a bed room the RF is around 1700. Something about that side of the house.
I just came back from a work trip where a client was crying about a radio station bleeding through his speakers. I was confident it was not my power supply, but I had to go check. In the end through various processes of elimination an use of filtration, I was able to validate his system preamp was a mess of noise and his phono preamp was not filtering out the RF from the cartridge, tone arm, phono pre enclosure. It is my experience through many people asking for my assistance to eliminate some sort of noise, I find the issue is the audio equipment itself that is the culprit. I have seen it with 3 year old 40K monoblocks to brand new $20K phono stages. I have never seen a clients noise issues emanate from a well designed electrical infrastructure using NM cable. Having said that, I have dropped Torus Isolation transformers on peoples racks and 2/3rds of people end up buying it. I sold 2 out of 3 on this last trip. There is a ton of noise on the power line. But it’s not noise you notice as a hum or radio. It’s a hazy veil most people don't notice. They just keep buying new gear trying to get better performance. Once you eliminate the power line noise, the music becomes more clean and quiet. Not black. The room feels more calm. Details are more present in the recordings and the bass becomes tighter and more integrated with the whole. The music is more natural. There is noise on your power line. Lots of it. But you’re doing nothing to get rid of it by wrapping a few feet of your infrastructure in steel or aluminum. Those that say shielded wire does not matter because there are hundreds of miles of wire that are exposed to noise injection have a very valid point. FWIW, that radio station bleeding out my clients speakers. You won’t fix that with an isolation transformer. You won’t fix it with any power line filter. You might fix it with about $25K in Faraday shielding around the room. That includes over windows, in doors, under the floor. Everywhere. You have to encapsulate the entire room. Or the entire rack. It’s possible a system set in a closed cabinet that is completely shielded will work. And then it’s a maybe. Better to get audio equipment that has a power supply designed to reject RF and not modulate it into the power supply of the audio equipment. Here is a good read. More important, go to the References and read all of those. I have read a lot of the materials noted in the references. https://cdn.cableorganizer.com/old-images/midatlantic/PowerSolutions-middle-atlantic.pdf
In summation, if you want the best power for your audio Ground Correctly Use all copper panels and wiring. This means the neutral and ground too. Segregate power Use an isolation transformer Use NM #10. Better to use twisted wire. Better to use grain oriented twisted wire. If your dead set on using metal encased wire, use an isolated ground system This is a very high level list. It lack all detail on how to set the infrastructure up properly. It’s basically a one line. |
@minorl Wow great post, thanks for that. I found that to be some of the best no nonsense AC information Ive read here. Also took a look at your system on your profile, wow again, any chance for some pics? Thx again! |
@gphill do whatever you fell is best for you. I'm not trying to argue with anyone here, however, ground loops occur if there is a voltage potential between the neutral and ground wires. The only difference between the two hots coming into a home is the phase difference in the AC legs. However, when that AC is converted to DC the PHase difference goes completely away. That is it. As I mentioned previously, sometimes people would connect to a hot leg that has noisy equipment connected to it or the grounding scheme in some audio equipment was improperly designed which causes ground loop issues. Dedicated lines have the hot, neutral and ground go back to the service panel without sharing. All circuit neutrals tie together at the service panel and all grounds tie together at the service panel. If the leg has noisy components (AND) the internal power supply of certain audio equipment isn't up to snuff to eliminate noise properly, then, you MAY have noise. if the grounding scheme in a particular audio equipment isn't designed properly (star ground, etc.), then you MAY have a ground loop. But, like I said before, connecting to two legs is okay as long as you know what is on the legs. Connecting everything to one leg is fine as long as you don't have arc welder amps that unbalance the system (noise anyone?) by drawing too much on one leg and unbalancing the system. This is why Refrigerators, microwaves, electric washing machines, etc. as connected as balanced loads on home systems. But I can tell you that people that claim to hear differences between all on one leg of split leg service, didn't do A/B comparisons (kind of hard to do that) and if they did, there was something else that caused the problem. like a really noisy equipment that was on that particular leg or worse, some audio component that didn't have a properly designed ground scheme. In older equipment you would find the signal ground (for audio) and the chassis ground was connected. not a good idea is it? Many people know that now but back then? not so much. Or there were multiple signal ground points in a circuit instead of star grounding at the same point (physically). Literally asking for a ground loop or hum problem. Has nothing at all to do with which AC leg was used. In my experience, I have never seen an issue with all low level components tied to a decent power conditioner and then to a dedicated line and separate amps tied to their own dedicated line. I have however many times found ground loops by the following method. unplug everything. Connecting the amp and speakers together only and turn the amp on. Noise? yes, amp is the problem. No? then connect the pre-amp to the amp/speaker combination. Noise? yes, pre-amp or (interconnect cables) is the problem. see where I'm going with this? Anyway, enjoy you system. I know you will.
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I have Pass Labs mono amps. Combined they pull 740 Watts at idle. Nice little heaters. Until I exceed the Class A bias current that wattage is constant. I think they are Class A up to around 80 Watts if memory serves. |
So the electricians are here today putting in my 3 dedicated power lines. I had a new square D QO 200 amp panel box installed with all new breakers. They also installed a 26kw standby Generac generator along with a whole house surge protector. For my new lines I’m using 10 gauge aluminum clad mc wire and eventually Hubbell 5362 outlets. I realize I could have done more, and in the end I may go with some kind of power conditioner for my front end, but for now this is going to be it. Looking forward to a better and cleaner sound. |
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I have two dedicated circuits using MC 12 AWG. Each branch is less than 40 feet long. One feeds the front end and one the mono amps. Originally, I had the two breakers side by side, ie. separate legs. Somewhere in these forums I read that it is better to have the dedicated circuits on the same leg. So I moved one breaker one space apart from the other which puts both circuits on the same leg. I think the stereo sounds better. Could I discern the difference in an A/B? I’m not sure. The two mono amps are pulling 740W, the front end is pulling up to 500W if everything is turned on. That’s 10 amps on one leg. (Same as running a microwave oven). I have a little voltmeter plugged into one of the dedicated outlets. It shows 120V right now and did not change when I turned everything on. (It does not show tenths of a volt.). Right now it is cold and all three heat pumps are running. I normally see 122V. That’s right, I just turned my stereo on at 6AM. I’ll listen to some morning music until the weather warms up outside. Retired living yeah! |
I disagree with most everything Minorl says. Keep it all on one leg. It matters. It not about the noise. If you have a good system, say AR Ref amps and an Esoteric CD player, you will hear it. It will be more clean and clear. If you have a Cary SLI80, you might not hear it. But you will still notice a 10AWG dedicated circuit vs a 12 AWG feeding the rest of the living room. I also have not been able to validate putting lights or motors on the same leg as audio is detrimental. The noise is also on the neutral. You can’t hide from it. I have tried this on many systems before I gave up on it because no one ever heard it. Make sure to use a quality dimmer such as a Lutron Maestro. That will filter most of the noise. I do put motors on a separate leg to reduce startup voltage sag on the audio phase. I do like a good filter. But the only one I have found to work to my satisfaction is a large Torus transformer that has everything on it. Including your modem, router and switch if you stream. I don’t like most other filters. They either collapse the sound stage or create an artificial "Black". If you don’t want to filter your audio, you segregate your power with subpanels and you filter the noise from your house. But what are you really doing. Not much unless your off grid "Island". And if your off grid, I am still going to suggest you put a Torus onto the circuits feeding the audio to filter the inverters high frequency noise. As well as any RF that is attaching to the power wiring. If RF is attaching to the phono cartridge, tone arm wire or case of the phono stage itself, you cant do much other than get a good phono preamp that is good at rejecting the noise and not letting it modulate into the power supply. If you happen to have a very large estate with pools and fountains, security systems, a server farm and a high end audio system, then segregating power and filtering the noise from getting back to the audio becomes something to consider. You probably have a dedicated utility transformer so your filtered from the street noise. You may want PFCC attached to a subpanel feeding the motor loads. You may want a UPS attached to the server farm and security system. You may want critical power with battery backup for light and refers in power outages. Most people don't have this. They share power with 5 neighbors on one transformer. Your getting all the noise from their dirty devices. So trying to segregate and filter your own dirty devices is a loosing battle. Your best option is to filter the line to the audio equipment. |
@minorl +1
I agree 100%! Mike |
it is not the end of the world, but, all lines on one leg is not accurate or necessary. Make sure you have dedicated lines to the panel. In other words, each hot, neutral and ground wire goes back to the panel directly and isn't shared by any other circuit. Each piece of equipment converts the AC voltage to DC internally, and they should have adequate noise filtering internally. Ground loops (hum) typically occurs when neutrals or hot is shared by other components and is not adequately filtered. When the neutral has an actual voltage present over the ground level, then yes, you will have a ground loop problem. This is why the grounding schemes within each component is very important. You have nothing to do with that, but some designers (not typically anymore) don't design the ground schemes adequately. You want to avoid putting components on the same legs as noise making components, like noisy lighting systems, etc. Large motors, etc. Most if not all adequately designed electrical home circuitry have balanced loads on each leg. That is code. So placing a large load on one leg unbalances the system and causes problems. My system and many that I have helped put together for others have circuity on each leg and there is absolutely no problems at all and shouldn't be. I'm an Electrical Engineer and also a Power Engineer (analog/digital design) for Aerospace and a Power Engineer for an Electrical Utility for over 45 years. I design and build amplifiers, filters, etc. also. I'm not trying to piss anyone off, but the "must be on the same leg" thing, is not accurate. Just avoid or remove noise making equipment. Also, I have noticed that it is a good idea to have the small signal equipment (CD player/transport, DAC, Turntable, Pre-Amp) connected to a decent power conditioner and then to a dedicated line and the amps connected directly to dedicated lines. This is why I always recommend at least three dedicated lines and not two. If you have more than one amp, then in my opinion, they should be on separate dedicated lines and the small signal equipment connected to the power conditioner and then to it's own dedicated line. If you have amps that are basically arc welders, then putting them on the same leg is not a good idea electrically. Anyway, your choice. I try to plan for the future. Start with one stereo amp, then yes, two dedicated lines. But, what happens when you decide to upgrade and go mono amps??? Have fun in your goals and enjoy |
@gphill. Nice Leviton receptacle for audio only $5.61 each. See below: Mike |
@erik_squires Wrote:
No offense, but I rely on Chubby Checker for doing the twist. LOL 😁 Mike |
Agree with the idea that getting rid of differential noise is best done with an isolation transformer rather than relying on AC cable twists. One interesting article I read a long time ago suggested that a significant benefit of armored cable in general, including bare-armored-ground (BAG), was that lightning surges were carried better by the armor than the ground conductor inside due to actual skin-effect issues with high frequency strikes. The armor seems to have performed as a very low inductance path. Can't say I noticed a big improvement in noise when I used it though. |
Remember the Dead Poets Society when Robin Williams told the kids to stand on their desks. To see the world from a different perspective. I don't even know if you all have put your boots on the ground. Wiring an AV room is not the same as wiring a 2 channel audio room. Proper grounding has little to do with the electrode in the earth. You don't use metal encased wire with a hot, neutral and ground. I don't care if its AC, MC or Steel/Aluminum pipe and wire. If you wrap you wire in metal you have to be very careful in how you do it. If you make a single mistake, you will have a very loud ground loop. Many recording studio are wired with metal raceways. And many of those studio have a large isolation transformer that feeds everything. But the guy who designed the infrastructure is many times at the site during installation to oversee the project and make sure the electrician does it right. An electrician is your worst enemy when it comes to powering your audio system. They will ignore the spec and drawings, say they know best, then ask for a change order to remove and replace materials they installed incorrectly. Your much safer using NM. And, you have to make a shop where you can limit variables and listen to what you preach. You have to go through 5 or 6 homes and step by step change out 1 variable at a time, then listen and learn. Let it sit for a couple weeks and get the owner feedback. Then go back and make 1 and only 1 change, then listen again and let it marinate. I have been fooled myself. I made a change to feeder ground and was all smitten with the resultant bass. The owner told me 3 days later to rip it out. It was all wrong. He could only turn the stereo on for about 1/2 an hour, then he was completely unsettled and turned it off. I changed it back and he said it was night and day better. He was back to listening for hours on end. I shared the experience with an industry professional and he explained why what we heard happened. WIRES HAVE A SOUND. Every one of them. Maybe your a denier and think every power cord sound the same. If that is the case, then why are you even arguing. It doesn't matter. If you do believe power cords have a voice, then why wouldn't 40 feet of wire in the wall also have a voice. Technical jargon is just that. Its indispensable to be educated, but you have to listen to what you do. I am constantly learning. I'm not perfect. I have made mistakes and stumbled. Like the ground above. But hey, the internet if full of people saying oversize your grounds. So I tried it. But every time I do experiment I know more. At times I go back to projects I did in the past and refine the installation to get a little more out of it. Like I said earlier, the NEC is a minimum. Just because it meets code, does not mean its anywhere near as good as it can be. If you decide to put some holes in your walls and bring 5 or 6 different wires from your distribution panel out to your rack with the same termination on the end to listen, I would love to hear your impressions. I like to do this with my amp and my DAC. As well as phono preamp at times. And don't forget to let it rest in your system for a couple weeks. There is a big difference between back and forth listening and living with something for a while. What might sound WOW to you at the moment might end up quite grating over time. I find 24 hours or constant play with maybe 2 or 3 on off cycles is enough time to get a wire stabilized to hear what its doing. |
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Just a guess you removed AC cable from Fremer’s house. Not MC cable. Heck I don’t think you have ever worked with MC cable the way it sounds. This statement of yours kind of says it all.
To be more precise there is a black, a white, and a green EGC. All three conductors are the same AWG size. The Insulation covering the wire is THHN. Here’s a picture of 2 wire MC cable for you to look at. Southwire 8 ft., 12/2 Solid CU MC (Metal Clad) Armorlite .... Here’s a picture of AC cable for you to look at. 12/2 x 250 ft. Solid CU BX/AC (AL Armored Cable) ...A 16 AWG bare aluminum bond wire to be used in conjunction with the armor for the EGC. AC is junk, imo.
It was manufactured in a spiral twist yesterday, and it will be manufactured in a spiral twist tomorrow, and the next day and the next day, and the next day after that. Like I said, I don’t think you have ever worked with MC cable.
Wheres that coming from? Read the OP’s original message.
You can have your opinion. I have mine. Of course there has been testing comparing NM sheathed cable to MC armored cable. NM works fine providing the installer of the cable takes extra care not to twist the cable while installing it so as not to distort the lay, placement, of the bare EGC between the two current carrying conductors. With MC cable that can’t happen. The Hot, neutral, and insulated ground spiral twist is held tightly together it’s entire length by a plastic wrap and the metal armor. Be it aluminum or steel. The testing I talked about. I have two white papers for you to read. An Overview of Audio System Grounding and Interfacing. Take a look at page 16. Read pages 31 thru 36. Pay close attention to page 35. Page 35 chart. Al armored MC cable beat out NM cable. I wonder how careful the techs were with the NM. I bet they didn’t twist it, changing that exact lay, position, of the bare ground wire between the two current carrying conductors.
Of course you can’t always count on it. . Power Distribution and Grounding of Audio, Video and ...Read pages 11, 12, and 13. Pay close attention to the chart on page 13. Again Al armored MC beat out NM cable. Oh and look at the picture of the test board. The NM is laying flat. No twists. Wish they would have tested it with at least a couple light twist in it. Just like in the real world. Good luck pulling NM cable without getting any twists in it. You still want to recommend NM cable over AL armored MC cable? .
There’s a sales pitch to buy your 2 conductor with insulated ground THHN, maybe, THHN/THWN twisted cable assembly. . Best regards, Jim . |
Southwire Armorlite 125-ft 10/2 Solid Aluminum MC Cable You sure you want to recommend this cable. Think of all the issue you are creating. I would never use it. Its what I removed from Fremers that was causing lots of issues. And I'm pretty sure its not twisted anymore. Most all that stuff is strait transmission line. Its held together so the impedance/capacitance is stable. If your really concerned about rejecting noise, put an isolation transformer in for amps. Size it to feed the whole system. Or use an Audio Quest type filter on the front end and amps to the wall. Either of those solutions will get rid of a lot of noise. MC does not get rid of any noise. The aluminum may block a small amount of RF on the branch only. Aluminum does not do much for EMF when cables are places side by side. I personally say stick with Southwire NM cable or spend more and get grain oriented twisted. |
Make sure you tell the electrician you want 10/2 with ground SOLID copper conductor aluminum armored MC cable. "MC", NOT "AC" armored cabled. Make sure he repeats to you it will be MC cable.
Be careful what you are buying now days when it comes to Hubbell outlets. Hubbell today it not the company it was years ago. Different owner. What are looking at buying? How many outlets are you looking at buying? |
I really appreciate all the helpful suggestions. What I’ve decided to do is 3 dedicated 20 amp circuits using the 10 gauge aluminum mc cable and eventually some nice Hubbell outlets although for inspection purposes the outlets will have to be cheap tamper resistant ones. Thanks again for all the help. |
@jea48 Wrote:
MC cable is manufactured in both steel and aluminum with twisted conductors that help reduce AC magnetic fields. Also, steel MC will help reduce EF. I am sure you know that. 😎 Mike |
