Taming 60 Cycle Hum
Hi folks. Welcome back to the Corner. This week we’re going to touch upon everyone’s favorite gremlin, 60 cycle hum. We all know the basics; keep it away from bright light, don’t feed it after midnight, don’t get it wet. What some people don’t know is there are a few basic steps that can be taken to ensure the quietest possible rig as well as some very easy troubleshooting that can be done in order to isolate the problem to a cable or a piece of gear. We’re going to have a fun little discussion on this today so read up and enjoy. If we don’t get deep enough into something or you have something to add, please post it in the comments so everyone can share the knowledge. That’s what this is about.
Bring the Noise
The first thing to consider is when the noise started. A lot of times if you can identify a condition (i.e. adding a new pedal, using new/old cables) you can identify the source of the problem. Since this is not always possible, we’ll go through a little troubleshooting guide to help out. The difficulty in doing this will vary depending on how large your rig is. If you’re simply plugging the guitar directly into your amp, this will be a piece of cake. If you’re hauling around 32 effects, two amps, and 4 guitars then it can take some time.
The easiest way to identify the source of noise is to strip everything out of your signal chain. Turn everything off and unplug all effects both in front and in an effects loop. If you have a cable tester, now’s the time to open it up and put it to work. Test ALL cables including speaker cables if you have a head/cab setup. If you don’t have a cable tester, pull out the newest or most reliable cable you have and start with it. Next, use your known good cable to plug the guitar directly into the amp (What? No effects? Don’t worry, this is only temporary). Turn it up and play. Is the noise still there? If yes, try another guitar if you have one on hand. Is the noise still there? If yes, try another cable. If you still have noise, there may be an issue with your amp or with the A/C line voltage (old wiring in houses and clubs is common). If there is no noise without your effects hooked in, start introducing one effect at a until you start getting the noise you heard. From there, unplug all other effects and run just that one that caused the noise. Is it still there? If yes, you’ve found your culprit. Be sure to check the patch cable associated with that effect as well. This can be time consuming but very worthwhile in reducing the overall frustration of tracking down noise. Now let’s talk about what to do about it.
So if the noise is coming from your guitar there are a couple of things to look at. First, if your guitar uses single coils (Strat, Tele) then switch to one of the “in-between” positions, this will be position 2 on a Tele and positions 2 and 4 on a Strat. Does the noise go away? If so, you’re dealing with good old fashioned single coil noise that is inherent in the pickups. If the noise doesn’t go away, you could be dealing with a bad ground connection in your guitar. Make sure the pickups are reverse polarity (neck in a Tele and middle in a Strat) otherwise these “in between” positions will not be hum canceling. Some 50’s spec Strat pickups are offered with a non RWRP (Reverse Wound, Reverse Polarity) middle pickup to be vintage correct. This will not be hum canceling and will emit the same hum as an individual single coil.
So what to do if all positions hum? If you’re handy with a soldering iron, pull it out and get ready. The quickest way to fix a bad ground is to just re-solder them all. If you cannot visually find a bad connection then making sure all of them are soldered well is a must. Don’t forget the ground wire that goes to the bridge! Once all grounds are secure, plug in and check it out. You should notice a significant reduction in hum, if not, you might want to refer to a guitar technician to have the pickups and electronics tested or pull everything out and completely re-wire the guitar.
Single coil hum is a hotly debated subject with guitarists. Some hate it but love the sound of the pickups while some can’t live without the hum on their Strat. The simple fact of the matter is this, if you want true vintage style Strat or Tele tone, you have to use single coil pickups and they will hum. There are a few ways to improve this though. First, a proper grounding scheme and cavity shielding treatment will usually reduce single coil hum to a minimal level. It won’t completely rid you of hum but it should help bring down the noise floor to the point where it’s not as annoying. This link is to an article on http://www.guitarnuts.com that is a fantastic walk-through of cavity shielding and “star grounding”. I highly recommend any Strat or Tele player read this even if you don’t implement it yourself.
There are also hum canceling pickup alternatives to single coils. By using a “dummy coil” manufacturers have managed to produce hum-free pickups that still retain most of the single coil charm. There again though, some people love them and some feel that they don’t retain all of the characteristics of a true single coil pickup. Suhr has an incredibly cool product called the BPSSC or Silent Single Coil Backplate for Strats. This cool little device actually has a dummy coil in the backplate that cuts hum from your Strat while retaining all the clarity and chime of the pickups. This is perfect for vintage pickups or simply the single coil enthusiast that wants to keep the original tone without the noise.
So if you’re finding the noise is originating in your amplifier, this is a tougher problem to tackle. If you’re playing a tube amp, have all your tubes tested for microphonics. A microphonic tube can be a sign that the tube is failing, which can cause all kinds of mischief. Simply take a nonconductive item such a pencil or chopstick and tap your tubes lightly one by one. If you hear any feedback or tones coming from the speaker, you could have a bad tube. Although an improperly biased amp could produce many different side affects, hum can be one of them some amps have a “hum bias” control on the back precisely for this reason.
Also, since tube amplifiers (especially vintage ones) are susceptible to line noise (from your wall) it’s always a good idea to have a high quality power conditioner. These can be pricey but with onboard circuit protection and noise reduction, a good conditioner is invaluable to the gigging guitarist. My amp has been saved from bad power surges several times and the high quality line noise reduction keeps the noise out at smaller clubs that shares power with lighting. Aside from these two tips on amplifier noise, if they don’t help it’s time to call the tech. Amplifiers contain deadly voltages so it’s not advised to go searching for loose wires or connections on your own unless you know what you’re doing.
This is where it gets tricky. Especially when dealing with vintage effects, noise is always an issue. Sometimes it’s the nature of the beast with that old Arbiter fuzz or Rams Head Big Muff. Vintage effects in general were not always quiet. If you have a vintage pedal that produces hum as well as an effect, there will likely be a mod out there somewhere to make it quieter. The most useful tool you can have in this case is an isolated power supply. Most wall warts should eliminate line noise but a solid multi-power supply with isolated outputs is your best defense. If there is a single pedal that is problematic even with the isolated power, try it with a battery instead.
For a large pedal board, make sure you have an isolated power supply, such as the T-Rex Fuel Tank
Ah yes… there could be a book written about ground loops and they can be tough to deal with. In my experience I’ve found a few tricks that have gotten me through the gig. First of all let’s talk about what a ground loop is. The most basic definition is a ground loop is a situation where there is more than one electrical path to ground. If these multiple paths are at the same potential, then there should be no issue but when they are at different potentials one can interfere with the other causing 60 cycle hum and possibly a shock hazard. Now this is a very basic explanation and there are plenty of knowledgeable folks out there who can explain it better so we’ll rely on help from the comments section on this one. I am certainly not a scientist!
It seems that I’ve most often encountered guitar related ground loops when using two amplifiers or an effects loop. I’ve also seen many people do things to prevent ground loops that I would never attempt. The first thing NOT to do is to clip the ground lug off your amplifier plug or use a ground lift adapter. I know you’ll see people on the interwebz telling you differently but don’t do it! Does it work? I have to use a ground lift when pairing my Echoplex with certain amps but lifting the ground on say a tube amplifier can cause high voltages to run across the chassis and also eliminates any protection your amplifier may have had from voltage surges and spikes. You could end up with a dead amp or a dead band mate so the ground lift is NOT recommended.
In lieu of a ground lift, Ebtech makes this stunning little device called a Hum X or Hum Exterminator. Simply plug it into the offending amplifier and plug into the wall. Gound loop hum is gone without lifting the ground and causing a dangerous situation. Basically the best you can do for a ground loop is to have good power and to make sure all your equipment is drawing its power from the same source. This is where that really expensive power conditioner comes in. Yes, it can cost more than you want to spend, but think of it as an insurance policy on your vintage gear. The conditioner will allow you to plug all your gear into one place, greatly reducing the chances of a ground loop in the first place. Also, a good quality, isolated pedal power supply is a step in the right direction. We’ve discussed these before but having each pedal’s power isolated reduces interference from outside due to the fact that there is no physical connection between the power input and output (transformer isolation). These two power units along with an Ebtech in your gig bag will virtually eliminate your chances of having issues with a ground loop.
This device will safely eliminate ground loop issues without lifting ground to your gear.
Noise Reduction Units
So a common question we get is, “Will xxx noise reduction pedal make my Strat stop buzzing?” The simple answer is no. Noise reduction units do not make anything stop being noisy, they simply mute any noise below the threshold you set. Since 60 cycle hum is a pretty low noise floor (usually) a noise reduction unit is probably not the best answer. By the time you dial out the hum (if you can) you will lose so much dynamic range on your signal that it probably won’t be worth it. Noise reduction units are normally best suited for eliminating noise (usually a hiss) associated with high gain or multiple gain stages. As you stack gain stages, each one amplifies the one before it, including any noise coming from the first one, on down the line. Noise reduction units are good for this but I’ve found they lack in combating ground loops.
Bring the Noise
So now that we’ve eliminated the noise in your rig (as much as possible anyway), it’s time to crank it up! If you’ve been dealing with noise issues for a while, once you quiet things down a bit, you’ll notice that you can attain higher volume settings as well as more tube saturation than before without the loud hum. That loud hum was probably covering up some of your tone so you might notice a clearer sound. While hum is annoying, we now know it can be beaten with a little effort. Thanks for reading and we’ll see you next time, in the Corner.