So, I'm rewiring my house to rid my amps of 60Hz hum

You will probably eliminate some line-based interference from other plugged-in devices, but that is not the major source of noise in most home studios.

It's all about RFI - Radio Frequency Interference. And all the power conditioning in the world won't help with RFI. Most of the noise you hear in modern audio equipment in the home studio is induced noise due to ground loops, cables, and single coil pickups all acting like antennae and picking up emissions from your lights, power lines, appliances, other equipment, local radio and tv stations, etc. Defeat the RF and you'll have a quiet studio.

Once you do this, then yes, perhaps most of your noise comes from AC line noise and internal preamp tube thermal and cathode noise. If you get to the point where those are your main problems, you are really winning the battle.

 

I am on my 2nd home and hence rewire and there are some basic things you should do-

-on your electrical panel you have 2 sides, left and right which represent 1 leg of 120vac each for the total of 240VAC single phase to the home. They have a seperate Buss below the breaker and then each Buss has its own Master Breaker with each one tied to one leg of 120vac. What you can do is re-organize your breakers so that any motors or dimmers are on the opposite side of where your studio outlet breaker('s) is/are. This will reduce the chance of noise through ground from other appliances.

How much is debatable but its the first basic step that usualy easy to do. If you find the wire is too short to work with, cut it back and mount a closed junction box then send to the panel.

-run dedicated 20 amp circuits for your studio and use a dedicated 15 amp circuit for any the lighting or motor devices of course like you stated and if you can afford spend big money on isolation equipment, at the very least some surge and power regulation which you probably know.

Be sure to use quality outlets so they are tight over time, some cheapys get loose and plugs tend to hang in them instead of a nice tight grab, this can cause line noise or even arcing in the worst case. In both of my homes some original outlets would buzz, you could hear them and this ends up on the line.

-at some point eliminate all passive dimmers or rheostats throughout the house and go with electronic dimmers

-research grounding your studio gear of course to miminize ground loops, there is some info out there

-you probably know but kitchen appliances, especially a microwave need their own dedicated 20 amp

That does it for EMI, RFI is a whole other topic and may I suggest lining your room with tin foil and fashion yourself a hat while your at it, just kidding

There is a story of a chicken wire cage being used to kill the hum on a strat when recording, maybe connected to SRV?

I mention RFI because I live a mile from a radio station and can catch the game on occassion with my Vox 847

Years ago I lived in an apt across the street from a home that had a ham radio junkie, I have him archived in some recordings.

Yes, do not use them at all but in other distant locations they generally dont cause line noise, its actually noise radiated from the bulb itself, so in the garage should be ok

 

ALL

ELECTRONIC

CIRCUITS

GIVE

OFF

RFI.

PERIOD.

But, yes, fluorescent lights are particularly bad. They shoot electrons between terminals with the intent that the electrons have enough energy to cause valence electrons in noble gases to get excited, jump to a higher orbital, and then discharge energy as light as they fall back to "normal."

The electromagnetic RFI happens as a byproduct of electrical currents.

 

Or you could go the extremist route that I did in my studio and install an Equi-Tech "balanced power" sub-panel with huge torroidal transformer.
Instead of the 3 prongs being 120vac/Neutral/Ground the entire system becomes 60vac/60vac/ground with extensive RF filtering. You keep the lights on the old 'dirty" power and don't get "clean power' near the dirty power lines.

They use them in most small-medium theatre systems and recording studios these days, and everything is dead-quiet with no ground loops. I was able to toss dozens of ground lift adapters that had been carefully installed to deal with the BS that all the rack gear....no need for them, poof, all noise/hum gone.

http://www.equitech.com/newproducts/newproducts.html

Paul

 

Great Thread! I just rebuilt my house 4 years ago, completely rewired with a separate 40 amp circuit to my studio and I've been struggling with noise ever since. I'm about ready to build a faraday cage around the damn studio!

 

Sometimes the noise is a combination of emi/rfi. Without minimizing the conditions that cause emi, your rfi problem can be compounded.

I had a detached garage at my old house which I had converted into a studio. I ran 60amp 240volt (2 legs of 120vac) to the building, 1 side for audio and the other for general purpose being careful to place the garage audio circuit on the opposite side of all noisy circuits in the home which I had previously regrouped.

You must also consider the aggregate current draw of all all breakers on each leg.

Trace your 40 amp circuit('s) back to the house panel and look at the points in my post and take those basic steps first before anything else since it will cost little or no money and then go further if necessary. You will find the solution to be the sum of several things, not just one

In my garage all of the outlets were in EMT conduit since it was a brick structure, were no walls to run wire through. This seemed to provide some additional shielding.

Short of the Equitech solution, there are isolation transformers that I think are the plug in variety and am thinking they start at 1200 or so.

One of the most important things that I forgot to mention and any home should have is this, if your home does not have a ground rod, install one immediately. Not only for safety but for adequate grounding of noise. Grounding through pipe is just not 100% safe nor noise free since water moving through copper can induce a slight voltage, causing noise.

The ground rod must be driven into earth to the depth of 8 feet minimum, truly a pain in the ass but is essential

Unfortunately there is not much info out there (thats any good) on the Farraday cage idea, but there is this to protect your "nads" from RFI!
http://www.lessemf.com/personal.html

 

I'm fortunate to live in a relatively new home that was wired to 2000 specs and standards. The downside is playing strats through a VOX amp with virtually NO 60 cycle noise at home. This has lulled me into a false sense of security about my gear.

Then, I show up at a gig and wonder why all this 'bad noise' is coming out of my amp!

Nothing beats good clean power at proper levels!

Good luck with your whole-house wiring project.

dave

 

The last thing most off circuit venues like bars/halls etc are concerned with is your electrical safety and noise issues. We used to play at a bar in philly where we had to run our own temporary electrical to the panel and tie it in, no kidding. I am talking seriously cheap bastards.

The reason was that the stage electrical was an afterthought and was not only inadequate, it was dangerous. Luckily we were prepared having done an outdoor thing at a public playground at the time, we had created a temporary power distro scheme using bx and gang boxes. This is what we used at that bar. Ultimately they went out of business of course, like all cheap bastards should.

They endanger us all and if thats how they care about electrical, this may be representative about how they serve food!

For gigs always test each outlet for polarity using a commonly available outlet tester and if you can check the ac line voltage.

If possible be sure you are using the same circuit as the pa power amps to reduce the shock potential due to different circuits possibly having different ground potential between them which ends up shunting through you when you touch your strings then put your mouth on the mic.

Its a blue spark to the lips, and its potentially lethal!

There is not much you can do to kill club ac line noise though short of an expensive isolation transformer but it can be minimized by making sure all of your connections are tight.

 

I have heard that having a separate ground (proper rod of course) for the isolated music circuit can help - any truth in this?

 

I believe there is something to it and may be required by code if your music circuit is routed to another building and then into a dedicated panel installed there. A ground rod driven at that remote panels location is necessary.

I have not heard of this when the circuit terminates in the same panel as the home wiring though. The point to the seperate ground rod above is that if you have wiring leaving the original structure, it is now susceptible to lighting or other hazards along its length and at its terminating point and a local groudn rod is the shortest distance to effective ground and is redundant to the homes ground rod.

Using a seperate rod when its in the same panel as the home could be worked out but it seems unecessary since that circuit terminates into ground at the same place as all other circuits with the shortest length of wire anyway since your at the panel deriving 120vac, it seems like overkill and you would have 2 rods not more than inches from each other.

There may be a special circumstance though when using isolation equipment and infrastructure where the input side to the iso equip is earthed with the home and the output side, the iso side is earthed on its own.

That would be the only exception since Isolation means your physically disconnected from drop wire and the VAC output using this technology is created induction.

Its like having your own scaled down pole transformer

 

isnt there something about having the earth cables runing from outlet to outlet that causes a problem.... and by running a a seperate earth cable from each outlet back to a technical earth which is a large cable either run from the main earth or to its own tech earth rod.....(i forget) tha helps eliminate the problem.....
i havent been in the elec game for quite some time but i remeber when i was doing the work for Broadcasting authority for the sydnay olympics that all the studios in the broadcast centre where wired this way.... just forget what happened as i said with the tech earth whether they had there own rod or was another cable of adequate size run from the main earth....
i imagine if it was its own rod and the potential between it and the main earth rod were slightly different that would be a problem... probably not much help there was i....

 

well it think pgissi said it better ha ha and has a better handle on it.....beat me to it whils i was prattling on...

 

my Strat, cable and some pedals have been good antennae for RFI. I've read that you can mod an amp to reject/filter RFI right at the input jack. True?

 

Well THAT would be fun.

I do the following things in the home studio to control RFI noise:

1) ALL line-level (1VAC+, eg. not my guitar cable) are transformer-isolated to prevent any possibility of ground loops. I NEVER defeat the shield at either end of a cable to break a ground loop, either by slicing the shield or through the use of a ground lift switch. There are some very efficient and transparent isolation boxes out there that solve the ground loop problem without sacrificing the efficacy of the shield on your cables. Cable shields work best when connected to RF ground at BOTH ends.
2) Any cable carrying a line-level or better signal is balanced. If the equipment to which it connects is not balanced, I use a short unbalanced cable to connect to an in-line converter that shifts things to/from a balanced signal. Very short cable runs can be an exception.

I manage to accomplish 1 and 2 above using the EbTech isolator unit.

3) All instrument-level (70mVAC-120mvAC) mono cables are well-shielded and as short as is practical/comfortable.
4) I keep all pedalboard cables as short as humanly possible and use well-shielded cable.
5) I try to avoid running power cables alongside signal cables. When they have to cross, I try to make them do so as close to 90 degrees as possible. I tape them down when I can, because they are mysteriously attracted to each other.
6) I stay the HECK away from my studio rack, amps, cabs, etc. when playing.
7) I don't use flourescent lights in the studio or the two adjacent areas of the house (master closet and foyer - easy in my case).

I am also lucky in that I do not tend to play single-coils. I do have a nice Strat that I occasionally use. If the noise really gets me, I use a gate or the ElectroHarmonix HumDebugger, depending on what sound I want. (Neither of these solutions is optimal, but Strats are what they are - and you really can't get their sound with humbucking pickups.)

Anyway - the home studio is pretty quiet.

 

You may have had some special circumstances there in the premise wiring and/or it was for broadcast application and in addition, different country, different codes. Your right in suggesting that the ground potential could be different with each drop having its own earth ground along with the possibility of creating ground loops.

Standards change and evolve as time and experience dictates so todays code and technical implementations may differ from older codes.

If you follow my home wiring guidelines which cost little or no money and if you can, beyond that spend some money on a pro installation using Isolation technology and the recommended premise wiring with it, along with following Laird's guidelines below you should be able to minimize any noise

Its really the sum total of things that ends up making a difference

 

Yes but it requires using a capacitor across the input which will filter tone to some degree, its not the prefered solution for guitar, you would only need a small value cap, maybe 1000pf but it will filter some top end.

You probably have noticed but in case you did not, turning your body/guitar while your holding it will find you the quiet spot and when you do your bucking the noise, humbucking that is using the earths magnetic field to achieve the cancellation.

A humbucking pickup is 2 coils wired in phase physicaly but put magnetically put out of phase by the bar magnet. Turning your body just a certain way accomplishes this magnetic out of phase condition between the noise and your single coil pickups, cancelling the hum for the most part although not as quite as effective as a humbucker.

So the best solution is to turn your body while holding the guitar if you dont want to go to stacked hummers or other so called "noiseless" single coils of which I have not tried

 

The National Electric Code requires your electric service to be grounded at only one point, at your service. Your neutrals are connected in your panel and are bonded to the ground at that one point. A second ground can create ground loops in the electrical system and is not allowed. outbuildings are covered under local codes. Seperately derived non grounded systems have their own rules in the codebook, usually high voltage systems in large manufacturing plants.

 

Regarding re-arranging your circuit breakers in the breaker panel to seperate the appliance motors from audio circuits-

Its ok to think of the breakers organized into 2 groups that represent each individual leg of 120VAC available in residential electrical service and label them left and right in your head for organizational purposes when deciding where to put the breakers with appliance motors versus where to put your audio circuit

but there is one important consideration when working in the panel and its how the left and right bussing actually works in most panels, there is a unique physical layout that you must be aware of.

The short of it is that each breaker position, descending in 1 column and not across them, alternate left and right, left and right. If you remove 4 breakers you can see this clearly by looking at the buss bars beneath them, you'll see tangs that represent the left and right staggered from position to position.

For example-

Breaker Position
1 = left
2 = right
3 = left
4 = right
5 = left
6 = right
7 = left
8 = right
9 =left
10 = right

etc etc and this is the same for both sides

The reason the bussing is laid out this way is to be able to easily provide a 240volt circuit using a Double Pole (ganged) breaker of proper rating which are manufactured in a side by side configuration and designed to tap into both legs of 120vac each to then deliver 240vac service.

Without this alternating physical scheme you would have to have an elongated breaker to stretch across the panel to the other side and your conductors would be seperated etc. the breaker would be cumbersome to work with etc.

Without the alternating position layout, a panel would be more messy than they usually are and maybe difficult to manufacture the breaker itself.