Power Supply or Pedalboard causing frustrating hum.

Itamar

Member
Messages
38
Hey guys, back in search of more techy answers here.
My pedal board has been adding a fair amount of hum (which is a little "phasy" sounding) and I was hoping someone could offer a solution to the issue.
When I plug my guitars (mostly humbuckers, all properly grounded) all is fine and dandy. There is a little hum but nothing more than you'd typically expect from an amp.
But, when I plug in via my pedalboard a fair (or perhaps unfair) amount of hum is added to the signal, even when all pedals are switched off. Switching the pedals on does not add any significant hum, if any whatsoever.
My current power supply is a Cioks Schizophrenic, so it should be of rather high quality. 6 isolated outputs, one per pedal.
I have one analog pedal (overdrive, true byspass) and five digital pedals (two of which are true bypass).

Now, the first thing I did was check if my cables are the problem. They seem perfectly fine - no rattle, no hiss, perfect condition and quite new.
Next I checked if the buffered pedals were causing the problems. In short, no. The was no difference when I removed them from the chain.
I checked the power supply, I get the same issue with my Harley Benton Power Plant Jr.

Now this is the weird part:
When I plug my guitar directly into the amp, and plug in the Cioks power supply to power the pedals, I get exactly the same hum - even though I am not running through the pedalboard.
I could really use some advice here.

If it makes a difference, everything is plugged into a 4 way extension cable out of one mains intput (only spaces on the extension cable are in use).
I also tried plugging the power supply into a different spot in the room and it didnt seem to making a noticeable difference.

My power supply and pedalboard are also placed very close to my amp and cab. Could the be a problem?
There seems to be additional noise/interference when put my hand very close to the power supply.

Any help would be greatly appreciated,
Thanks.
 

cosmic_ape

Silver Supporting Member
Messages
6,703
Two things.

1. Check mA requirements on each digital pedal. You may be going overboard. There are only a few power supplies that can handle five digital pedals at the same time.

If this doesn't solve it, then...

2. Does this happen at your place only? Have you taken your rig somewhere else and compared?

I mention this because sometimes it's the wiring in the building. My last apartment was relatively new. My rig is all isolated and is dead quiet. When I moved to my current place, which was built in the 60-70s, I now get a little noise. I searched for ground loops and such with no luck. But the noise is still there, especially when using pedals.

I did what you did and plugged the amp to a different outlet than my board. I went on different rooms. No luck. It wasn't until I did my first gig in that neighborhood that I got to play my full rig somewhere else. Guess what? Quiet as it used to be.

Given how much I love my new neighborhood, I have decided to play around it, as if it was 60 cycle hum. I can still find a sweet spot where the hum is minimized. Oddly enough, when I play a LP, the spot and angle I have found to be the quietest is perpendicular to where I sit when playing a Strat. Go figure.
 

Bshecko

Member
Messages
1,090
My power supply and pedalboard are also placed very close to my amp and cab. Could the be a problem?
There seems to be additional noise/interference when put my hand very close to the power supply.

Any help would be greatly appreciated,
Thanks.
Yeah that definitely could be a part of it and since you completely bypassed the pedalboard I doubt it's a pedal. If I were having this problem I would get a long extension cord and plug the power supply into the furthest room I could in the attempt the hopefully tap into a different circuit than the amp. Set the power supply at least 5 feet away from the amp and turn the lights off. Fluorescent lights create noise in some venues I've played. Is this doable?
 

ummohyeah

Member
Messages
1,848
I mention this because sometimes it's the wiring in the building. My last apartment was relatively new. My rig is all isolated and is dead quiet. When I moved to my current place, which was built in the 60-70s, I now get a little noise. I searched for ground loops and such with no luck. But the noise is still there, especially when using pedals.
This could be the case. I ripped apart my board twice the other day trying to eliminate this hum... Then remembered that the light switches in my living room cause a ton of hum (you can hear it when the lightswitch itself just turned on).
 

TheoDog

Silver Supporting Member
Messages
19,821
How close are you to a computer monitor and/or wireless mouse when hearing the hum? Ceiling fan?
 

stinkfoot

Member
Messages
6,128
Which Schizophrenic? The old one (plastic case) or the Link version? Also, list the specific pedals you're using - analog vs digital is far too vague a description.
 

Itamar

Member
Messages
38
Two things.

1. Check mA requirements on each digital pedal. You may be going overboard. There are only a few power supplies that can handle five digital pedals at the same time.

If this doesn't solve it, then...

2. Does this happen at your place only? Have you taken your rig somewhere else and compared?
I am definitely well within the limits of the mA requirements. The Cioks Schizophrenic has a fair amount of juice.
I haven't taken my rig anywhere else to compare, as I haven't gigged in a while. I'm not sure quite how old my house is either, but if i ha to guess I'd say it was built in the late 60's.

Yeah that definitely could be a part of it and since you completely bypassed the pedalboard I doubt it's a pedal. If I were having this problem I would get a long extension cord and plug the power supply into the furthest room I could in the attempt the hopefully tap into a different circuit than the amp. Set the power supply at least 5 feet away from the amp and turn the lights off. Fluorescent lights create noise in some venues I've played. Is this doable?
Yeah, I'm 99% certain that my pedals are not the cause of these problems. I will have a go at plug the power supply into an outlet that is further away from the amp. I don't have fluorescent lights in my house, so that won't be the cause.

Which Schizophrenic? The old one (plastic case) or the Link version? Also, list the specific pedals you're using - analog vs digital is far too vague a description.
It's the Link version.
Pedals are:
Marshall Regenerator
Mooer Hustle Drive
Boss NS-2
TC Flashback
Marshall Reflector
Ditto Looper

I'm hoping to add a Digitech Polara and TC Sub'n'Up soon, but I'd quite like to solve these issues first.
 

Itamar

Member
Messages
38
I think it's worth noting that both of my power supply seems to have this hum when i plug them into the electricity, regardless of whether or not that are connected to any pedals.
Is this normal? Or does it hint the the electricity or the houses ground loop could be the problem? And why would my amp pick up this noise?
 

stinkfoot

Member
Messages
6,128
Really odd, this. If you unplug the pedals from the power supply (so it isn't actually powering anything), and run the guitar straight to the amp, do you still get the hum?

Other things to check:
Make sure the input voltage selector on the power supply is at the correct setting for your mains voltage.
Make sure the extension cable (and the wall socket it connects to) is properly grounded.
Try running a long extension cable from a socket in a different part of the house (to get it on a different circuit).

Also, you say the power supply is very close to the amp. How close, and does anything change when you move it?
 

Itamar

Member
Messages
38
Really odd, this. If you unplug the pedals from the power supply (so it isn't actually powering anything), and run the guitar straight to the amp, do you still get the hum?

Other things to check:
Make sure the input voltage selector on the power supply is at the correct setting for your mains voltage.
Make sure the extension cable (and the wall socket it connects to) is properly grounded.
Try running a long extension cable from a socket in a different part of the house (to get it on a different circuit).

Also, you say the power supply is very close to the amp. How close, and does anything change when you move it?
If I remember correctly I do still get hum when it isn't powering anything, I'll double check later.
I did notice a few hours ago that that although I do get hum even when the guitar is plugged directly into the amp while the power supply is powering the pedals, the hum definitely is a little worse when I run through the pedalboard. A vague whistling sound because audible, and the hum because a tad more aggressive.

I usually have the power supply centimeters away from the cab, and about a meter from the head, which sits on top of the cab. I did try moving the the power supply about a meter and a half further away and using a different outlet this morning but it didn't seem to help.
 

stahlhart

Member
Messages
2,444
Are all of your AC cords 3-conductor? Have you tried others in their place?

I know that the Cioks ought to be a good quality power brick, but have you tried another one in its place to be sure there isn't a problem with it?

Have you tried lifting DC ground to any of the pedals in the chain? The Voodoo Lab Y cables have this feature built in. There should already be common ground for all of the pedals through the signal cables and pedal enclosures.
 

stinkfoot

Member
Messages
6,128
I usually have the power supply centimeters away from the cab, and about a meter from the head, which sits on top of the cab. I did try moving the the power supply about a meter and a half further away and using a different outlet this morning but it didn't seem to help.
That's not at all unusually close, so it should be fine. How close to the guitar is the power supply? And does the noise change when you move the guitar in relation to the power supply? Or - to put it another way - is the noise the same regardless of if the guitar volume is on or off?
 

DaveKS

Member
Messages
16,706
Start at the beginning. Test your circuit 1st.



Then get a isobar, each vertical pair of sockets are AC isolated and noise filtered from the other pairs. Amp in bank 1, pedalboard power supply in bank 2.

 

Itamar

Member
Messages
38
Are all of your AC cords 3-conductor? Have you tried others in their place?

I know that the Cioks ought to be a good quality power brick, but have you tried another one in its place to be sure there isn't a problem with it?

Have you tried lifting DC ground to any of the pedals in the chain? The Voodoo Lab Y cables have this feature built in. There should already be common ground for all of the pedals through the signal cables and pedal enclosures.
Yes, I have used a Harley Benton Power Plant Jnr, as well as a few spare PSU's that I have. The problem is consistent.
Could you explain what you mean by lifting DC ground? I'm not sure how to do that...

That's not at all unusually close, so it should be fine. How close to the guitar is the power supply? And does the noise change when you move the guitar in relation to the power supply? Or - to put it another way - is the noise the same regardless of if the guitar volume is on or off?
My guitar is about a meter and a half from the power supply typically. The noise does get louder as I move the guitar closer, but that could also be due to the fact that I'm moving the guitar closer to the amp at the same time.
The noise dies when I switch off the guitar's volume.

Start at the beginning. Test your circuit 1st.

Then get a isobar, each vertical pair of sockets are AC isolated and noise filtered from the other pairs. Amp in bank 1, pedalboard power supply in bank 2.
Thanks for the suggestion. I see that Tripplite products only seem to be sold in the US and are compatible with 120V. I need 230V... do you have any suggestions for something that I can find in Europe?
 

Itamar

Member
Messages
38
Along with the above questions, I'll give a short update:

I carried on with the diagnostics and found a few interesting, and rather confusing, results.
1) My buffered pedals significantly increase the buzzing when they are in the signal chain, and if I a power cable that is connected to a buffered pedal over or near the power supply, the hum increases even more. If I take a buffered pedal out of the signal chain, the hum slightly decreases. BUT - If I take out all 3 of my buffered pedals and leave only my true bypass pedals I somehow get and absolutely awful and loud buzz which i worry could even damage the amp. I'm stumped.

2) I notice that my Strat in the 2&4 (noise cancelling) positions suffers less that my Ibanez Pat Metheny Hollow Body with a humbucker, which in turn suffers less that my Les Paul with BKP humbuckers (which I'd expect because the Les Paul has very slight grounding issues). I don't have a clue why the problem is least evident with the Strat, but even then it is still evident enough to drive me crazy. I haven't compared the noise recently with my Mayones because it's awaiting a set up, but if I remember correctly, it is also susceptible to this noise.

3) My TC Sub'N'Up (NPD woohoo!!) seems to ever so slightly decrease the hum when switched on, probably something to do with the pedal re-processing the signal. Probably doesn't mean anything though.

4) The effects loop is incredibly noisy atm, because the hum in the effects loop is not affected by the preamp or guitar volume. My effects loop is unusable until i can solve the hum issues.

5) Even with my guitar plugged in direct I get lots of noise. Far to loud to be normal, but it's not the some type of noise that I get when running through the pedalboard - the power supply/pedalboard adds a very aggressive buzz and whistle.

That's all I can remember for now i reckon... help would be massively appreciated.
Thanks
 

Bshecko

Member
Messages
1,090
You mention in your original post running direct to amp with power supply on but without any pedals connected. You also mentioned a squeel and I instantly thought about tubes. Are we troubleshooting the wrong thing? Have you run direct to amp with power supply off? Did I miss this?
 

stahlhart

Member
Messages
2,444
Yes, I have used a Harley Benton Power Plant Jnr, as well as a few spare PSU's that I have. The problem is consistent.
Could you explain what you mean by lifting DC ground? I'm not sure how to do that...
The pedal usually sees ground in two places -- the power cable, and the shielding/connector housing for the in and out patch cables. If you had two pedals both connected to the same power supply and patched to each other, you could disconnect the DC ground from one of the two supply cables and both pedals should still have power, because one of the pedals sees DC ground through the patch cable from the other.

The "Y" cables Voodoo Labs supplies for connecting two pedals to a single port has no ground connection to one of the two, and the wire for it is marked. It's a potential source of a ground loop.

You could probably simulate lifting ground to individual pedals, if they are battery powered, by running them one at a time from a battery for troubleshooting. You would probably need at least a test DC cable that only has (+) connected for pedals that can't be powered from a battery.
 

stinkfoot

Member
Messages
6,128
My guitar is about a meter and a half from the power supply typically. The noise does get louder as I move the guitar closer, but that could also be due to the fact that I'm moving the guitar closer to the amp at the same time.
The noise dies when I switch off the guitar's volume.
This bit is really important. Any noise that goes away when you turn the guitar volume off is coming from the guitar itself. Most likely, the pickups are picking up hum from electro-magnetic fields in the room. Single coils are the worst at this (except strats with RWRP middle pickups, which are generally hum-free in position 2 and 4), while humbucker guitars tend to be much less sensitive.

The mains transformer in the amp is emitting an electro-magnetic field, as is the pedalboard power supply (although at least with the Schizophrenic, with its toroidal transformer, to a much smaller degree). So you may have to move around in relation to those sources, to find a quieter spot. And of course, distance is your friend. So here's what I'd do:
  • Move at least two meters away from the amp, and turn around to where the quietest spot is
  • Keep the pedalboard at your feet (so it too doesn't sit as close to the amp)
  • Check that all signal cables are properly shielded and of good quality
In the end, you may also have a noisy room, full of EMF interference from other sources. Try moving the rig to another room or location, and set it up the same way (with the same relative distances). If things get much quieter, there may be something in your first location that emits a strong EM field.
 




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