What’s that Sound: Noise and Your Signal Chain

Have you ever powered up your guitar rig and experienced a low frequency buzz or hum from your amplifier or speakers? Or perhaps a high pitched whine when connecting your effect pedals to your amplifier?  If so, you are probably experiencing a ground loop or digital noise in your signal chain.

Ground Loops and Stereo Rigs

Grounding is an important part of your guitar rig. It’s used to protect you and your gear from dangerous voltages in the case there is a failure in your equipment.  It’s also important in preventing any additional noise from entering your audio.

Ground loops can appear when there are two or more devices connected to a common ground and can sound like a low frequency hum, similar to touching the end of an instrument cable connected an amplifier.  This typically happens when you are using a stereo guitar rig with two grounded amplifiers.  The current that is flowing through these different ground connections can cause a 60Hz hum in your audio.
Stereo Amplifier Rig - Ground Loops

Some things to try when you experience a ground loop are:

  • Plugging both amps into the same circuit or power strip.
  • Lifting the ground on one of the amps. Some amps have a ground lift switch for this.
  • You can also use a prong adapter that eliminates the ground prong for just the second amp.
    • ***Make sure to remove this ground-lift adapter when using the amp by itself.  Grounding is important for your safety and that of your equipment.***
  • Cutting the ground/sleeve wire on the cable connecting the last pedal in your chain to the second amp.
  • Getting a ground hum eliminator box between the pedal and one of the amps.  Ebtech makes several products for this.

Avoiding Digital Noise

If you’re powering pedals with a non-isolated power supply, noise can creep into your signal. You can experience digital noise in your audio if you are using digital pedals that are being powered along with other pedals by a power supply that does not have isolated outputs to power each pedal.

Daisy chained power supply

This digital noise, which can sound like a high pitched whine, is filtered from the audio outputs of the digital pedal, but will leak into the audio signal of the other connected pedals through the shared, non-isolated power connection.  The best remedy for this is to power the digital pedal with its own power supply, or use an isolated, multi-output power supply (like the Strymon Ojai or Zuma) to power up your effect pedals.

Powering your pedals

BigSky powered by factory power supply and analog pedals powered by a daisy chain type power supply.

GroundLoops4

Strymon Ojai provides isolated power to all your pedals to prevent noise and ground loops in your audio.

Proximity Noise

Another manner for noise to appear in your signal is due to the proximity of your pedals or your guitar pickups to other electronic devices.

Certain pedals, especially Wah pedals, when placed on top of or near external power supplies will add noise to your audio signal.  You can also get noise if your your guitar pickups are near TVs, computer monitors, or even other pedals.  The best way to avoid noise from any of these scenarios is to physically move these pedals or your guitar away from these electronic devices.

If you are experiencing a ground loop or other noises in your audio, please try out the suggestions above.  If you are not sure or need further help with noise, we’d be happy to assist. Feel free to send us an email to support@strymon.net.

About Hugo
Hugo Hugo is Strymon’s customer support manager and calm voice of reason. When his cats stop yelling at him for food, he spends his time driving through local canyon roads and running marathons. He also loves to noodle on guitar and play old Nintendo games.

26 Responses

  1. James says:

    Thanks! I have issues with my rig with a high pitch whine and while I do have a 1spot isolated power source for all my on-board pedals, it is near my computer and my wah pedal is near a few other power supplies for my Digitech looper pedal and amp switcher. Thanks for the extra bit of info for troubleshooting–I’ll try this tonight.

  2. Scott Whitacre says:

    Do you include different plugs for the power supply pedals to accommodate reverse polarity wah pedals etc?

  3. Donotrecommend says:

    Never get used to using a 3-2 prong adapter. Never cut off the third prong. These things are there to save your life. If You get ground loops, have amplifiers designed to ground lift, which accomplish this much more safely than dangerous and possibly illegal conversions.

  4. Donotrecommend says:

    See here: “The ground lift switch breaks the ground loop by disconnecting the shield of the direct output from the amp. It leaves the AC safety ground connected from the chassis to the wall outlet. This is the opposite of using a 3-to-2-prong AC adapter, which leaves the shield connected and opens the safety ground to the wall.”

    Ground lifts that are built into amplifiers are safer. 3/2 converts and sawing off the ground pin are not.

  5. Eric says:

    I just got the Ojai. Im geting a rain like noise and an hiss threw my vox ac4. The peddles that I’m using are, polytune, Flint and ditto looper, in that order. This noise only happens when pluged into the Ojai. Not near any othe electrical equipment- computer ECT. Thanks.

    • Hugo says:

      @Eric – That is strange behavior we are not familiar with. Can you please send us an email to support@strymon.net with details on how your whole rig is powered (are the amp and Ojai plugged into the same power strip or wall outlet, for example). A video showing this behavior and your connections would also be helpful.

  6. Kristopher De Tar says:

    I just purchased a Strymon Zuma to power my 5 pedals and now I have horrific buzzing which did not exist before, i am greatly dissapointed in this product because I had heard it was a quiet unit. Quiet in compared to what?

    • Hugo says:

      @Kristopher De Tar – Sorry to hear that you are having trouble with your Zuma. We have seen where using a cable with a bad ground connection in your signal chain will produce a ground loop buzz in your audio. You try powering and playing through 1 pedal at a time in your signal chain, and adding pedals until you experience the noise to determine where the problem lies. Or try checking one cable at a time in your signal chain with a different replacement cable to verify if this clears up the problem. Make sure to swap your instrument cable and cable from the last pedal to your amp to see if this helps.

  7. Meteoroz says:

    I have the Strymon Flint as the last pedal in my effects chain, and I get a high-pitched whine when switching to the 60’s or 80’s reverb modes. The 70’s is fine. Any idea what could cause this? I’m not using a Zuma or Ojai.

    • Hugo says:

      @Meteoroz – Sorry to hear that you are having trouble with noise in your setup. Can you please tell me how you are powering the Flint pedal? Does this happen with the 9V DC power supply that it comes with? Powering with a daisy-chain or multi-output power supply that shares its current across the outputs will result in a high pitched noise at the output like you describe. You must always use an isolated power supply or multi-output supply with isolated outputs like our Zuma or Ojai power supplies to avoid any additional noise in your audio.

  8. mark sendra says:

    I get hum when I connect my pedal board in a four cable set-up. The signal chain goes guitar to tuner, overdrive, front of amp. Effects send into boost, mod pedal, flanger, delay, reverb to effects loop return. All pedals are powered via isolated outputs of a pedal train power supply, all patch cables are George L’s, and hum is present with guitar cables or newly installed pedal snake. Any tips I may try?

    • Hugo says:

      @mark sendra – From your description, it sounds like you may have a ground loop in this setup. If you place all of these pedals in series before plugging them into the front of your amp (eliminating the effects loop for this test), do you still get the same hum? If not, then the ground loop is coming from the additional ground connection your pedals in the loop are receiving from the Effects Return. In this case, you can either place a Hum eliminator box between the output of the last effect in the loop and the Effects Return, or cut the ground/sleeve connection for the cable that connects between those 2 jacks to effectively lift the ground and eliminate the loop.

      Another possibility is that there could be a bad ground connection with one or more of the George L cables. We have seem many issues from customers using solderless cables causing ground connection issues that result in noise.

  9. Greg says:

    I had a relatively inexpensive brand X power supply setup and I was having all sorts of weird issues with cables, power cords, pedals, hums, delays, etc. I only had three pedals at the time which made it even more frustrating that I was having those issues. I swapped out pedal cables, guitar cables, used one pedal at a time and all sorts of configurations to try to sort out and identify each of the various problem(s) were.
    The end result of all that madness was I researched this on the web and came across the Strymon website and immediately looked into your power supplies. I briefly considered the competition (think black boxes that are in every guitar supply store!) but upon further investigation (web and YouTube) I learned that even those very popular black boxes were having issues now and then. So I stepped up, ordered the Strymon Zuma, it shipped amazingly fast out here to Seattle area. As soon as I connected the three pedals and powered the Zuma up all of those problems disappeared completely, Everything worked perfectly, no hums, no pedal delays, all other previous issues gone, just pure clean sound, it was such a relief. The multiple, high power, isolated channels on the Zuma are key as they kill most problems before they have a chance to sneak into your configuration. As mentioned elsewhere, things like Wah pedals and such demand additional attention but I’m confident as I add pedals down the road the Zuma will power and protect the pedal chain. For anyone looking at pedal power I simply cannot give higher accolades to the Zuma, it works flawlessly and looks so good I’ll be placing it on top of the board with the pedals!.

  10. Henrik says:

    I use an amp-switching pedal from Lehle, the Dual SGOS, which has stereo capability.

    http://lehle.com/EN/Lehle-Dual-SGoS

    The important part is: “Hum loops are completely excluded, thanks to electrical isolation of outputs A and B by the Lehle LTHZ high-end transformer.”

    Works great as the last in the chain before the amps! Also allows you to match the output level between the signals going into the amps.

    Cheers

  11. Henrik says:

    Oh, and the Lehle SGOS has a ground lift button 🙂

  12. John says:

    I just got my sunset it sound great but what can i do about the 69 cycle hum? I have a Strat with noiseless pups

    • Strymon Matt says:

      @John — Sorry to hear you are having trouble. Noise issues like hum from the AC outlet isn’t something inherently common to our pedals. Please email us at support@strymon.net and we will be happy to try and help you troubleshoot your noise troubles.

  13. Serge says:

    Hi! My Timeline is connected to a Voodoo Lab 4×4. But when you turn on the effect, a whistle appears. What could be the matter?

    • Matt says:

      @Serge – Are you powering more than just the TimeLine off one of the outputs? A noise like this is usually an indication that the pedal is not isolated off the power, and a ground loops has formed. Digital pedals do not like sharing ground through their power supplies. If your outputs are not properly isolated, or if the TimeLine is being daisy chained from an output, you will experience a noise like this. Please try powering your TimeLine with the factory power supply and see if the issue persists.

      • Serge says:

        Thanks for the answer! The problem was in my inattention 🙂 The Timeline was plugged into a 12-volt connector. After I switched it to a 9 volt socket, the whistle disappeared.

  14. Mark Dunbar says:

    ooops kiss the warranty goodbye.

  15. george says:

    hey men why when the power cable moves inside the dc in jack my pedals make a scratchy sound and sometimes lose power at all? they are a couple of analog pedals nothing digital or something it seems that the power jack is cheap does it matter?

    • Hugo says:

      @George – I’m not quite sure why your pedals would make that noise, but I do know that the jacks should not be moving around in the jacks while performing. I would make sure that you secure your pedals to a board along with all audio and power cables to prevent this from happening to begin with.

  16. Andrew Karns says:

    I have an issue that is strange. I am using a Marshall dsl40cr. I have about ten pedals. 4 connected to amp input and 6 in the fx loop. On the high gain channel, I get what sounds like a ground issue hum. When I take the cable that is normally plugged into my guitar and hold it over the pedals on the input side, the sound gets much louder. But when I hold it over the pedals in the fx loop, the noise almost completely disappears. Any ideas what I should try?

    Thanks,

    Andrew

    • Hugo says:

      @Andrew Karns – Sorry to hear that you are having trouble. From your description, it sounds like you may have a ground loop in your setup that more than likely exists with both high and low gain channels, but the high gain significantly raises the noise floor along including the ground loop hum. You should try lifting the ground on the cable connecting to the EFFECTS RETURN from the pedals with either a ground eliminator box, or cutting the ground sleeve wire on that cable to see if it clears up this hum. Please send us an email to support@strymon.net if you have further trouble.

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