Dirty power -- you might have heard the term before but chances are you’re like most people out there and have little to no idea what it actually means, let alone what it has to do with music. Essentially, the term known as dirty power referrers to the uneven electric currents that result from older wiring or improperly wired AC circuits, such as you might find in older homes or venues. Take a look at the two waveforms below for context. Anyways, this can cause annoying issues that result in unwanted line noise due to the erratic behavior of the waveforms and their effect on electric components; these components want the top of the wave form but end up getting the bottom, so to speak. What makes dirty power and the line noise it creates even worse is that those unaware can cause themselves a ton of unnecessary stress trying to find the cause of the problem – typically looking towards their gear – when the actual cause is not their gear at all.
But speaking of line noise, old wiring and AC circuits aren’t the only culprits as this can also be caused by large appliances, some computer monitors, nearby large radio transmitters and even fluorescent lights, not to mention older AC circuits that haven’t been updated to current electrical standards. And if you happen to hook up your guitar rig to a dirty power source, you’re going to have a bad – and noisy – time. So, what can be don’t about it? Well, the bad news is that there are only a limited amount of options but the good news is there are a few things you can do to prepare for this type of noise.
What To Do
The first thing that can be done to avoid dirty power sources and the line noise it creates is by knowing what a ground loop is, what it does and how to avoid one. In essence, what you want to do here is to make sure your guitar rig setup is ground loop free. Making sure there’s no ground loop in your setup won’t protect you from ground loops found at a venue or what have you but it will at least save you the headache of having to troubleshoot your rig to find the problem area.
The next thing that can be done is knowing exactly what else is connected to the specific circuit that you plan on using for your setup. The easiest way to do this in your own home is by checking the breaker box for the plug that your amp is using and see what else is hooked up. If you shut down the breaker that your amp is on and see that the fridge turns off too, it’s best to find a different outlet for your gear. Remember, refrigerators, fluorescent lights, large appliances, water heaters and even some HDTVs can cause line noise so it’s best to avoid the circuits they’re connected to. If possible, its best to find a circuit that only shares power between a single room, that way you always know what is on when you hook up your rig.
Unfortunately, unless you’re an electrician or own the venue yourself, chances are highly likely that you’ll have no control over which circuit you’ll be using during your gigs, so the next best thing to do is to be prepared. Clubs that tend to share stage power with the lighting tend to be affected by dirty power, especially if they use dimmer switches as they tend to create more and more line noise as the lights are dimmed. The first thing you should do to be prepared is to know the club you’ll be playing at. Most clubs that have live music on a nightly basis will almost undoubtedly have the stage power isolated from the lighting. Still, this will not completely guarantee that there will be a complete lack of noise in the lines but it will at least drastically reduce the chances of getting dirty power. If it’s your first time playing at a certain venue, don’t be afraid to ask them about the power. If the booker or owner can’t tell you, ask the sound ma. Have them show you where you’ll be plugging in and if they do happen to have any lights on a dimmer, simply let them know you’d prefer they not be used during your set. They will most likely accommodate you as long as your request is within reason.
Although you might have heard otherwise, the next thing that you should seriously consider purchasing, if you don’t own one already, is a power conditioner. There’s a lot of talk out there that these are useless but that’s only because they haven’t faced those situations where a power conditioner means the difference between your gear getting completely ruined or not. And I’m not talking about any old surge protector either as you’d need one that has line filtering as well (such as those made for specifically for music gear). The line filtering will reduce or remove line noise while the surge protection will protect your expensive gear in case of a brownout. The specs on the power conditioner will read in dB, rating a specific frequency. The higher the dB rating the more filtering will be available and the quieter the unit will be.
Taming the Noise
As touched on above, not all conditioners are created – or priced similarly for that matter – so it’s best to find one that fits your specific needs. I don’t have to tell you that if all you’re looking for is a conditioner to plug in your amp and pedalboard you won’t be needing one with 8 outlets, especially since those tend to run in the hundreds of dollars. Also, if you play at, a power conditioner might not be the best investment as you can easily find a less expensive solution like an Electro Harmonix Hum Debugger or similar units. These boxes are individual units that filter one plug at a time and are perfect for use at home or even a studio. You can technically use them for gigs but chances are you’ll be playing with a band and will more likely benefit from a multiple outlet power conditioner.
For live gigs with a band, that 8 outlet power conditioner mentioned above is probably your best bet. That single unit should be able to protect not only you but the other guitarist and bass player from noise and power damage as well. This will definitely be a much more convenient solutions than lugging around those Hum Debuggers for every player, not to mention those won’t protect against power surges. Also, this ensures that you will only need one outlet for all of your gear and the cost of the admittedly pricey power conditioner can always be quelled by every band member pitching in. Just make sure the unit you intend on buying is rated for the power you require and that the gear you’ll be plugging into it isn’t going to consume large amounts of current. Beyond that, you should be good to go. Power conditioners also prevent ground loops from your setup. Companies like Furman and Monster make high quality, filtered power conditioners that will eliminate noise and stabilize incoming line voltage.
And one last thing – under no circumstances should you use a ground lift. They work great in reducing or eliminating ground-related noise when connecting signal lines from two or more pieces of equipment but they weren’t made with music gear in mind, so in order for them to work as intended, you’re going to have to remove the safety earth from your amp which can easily send you to the hospital, if not the morgue.