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noise problems

Posted: Tue Feb 09, 2010 9:41 am
by buz
hey all, I finally finished my rig.
There is some humming, slight humming through the amp when all loops are off.
I think my cheap pedal power, doesn't help coz when i switch on those loops the noise gets louder, esecially when i use my little muff and mxr dyna comp.

i'm sure i can work that out, but what is concerning me is that my ground control pro clicks in the amp on certain setting when i hit the pots, any explanations would be great, all the best

Re: noise problems

Posted: Tue Feb 09, 2010 11:55 am
by JohnClark
To eliminate/confirm the power supply as the culprit simply power your effects with batteries to test for the sound to remain/disappear. I will assume you have some other power supply for your pedals and not a specifically a Pedal Power.

For the amp popping i guess I need more information... What amp are you talking about and how are you controlling it via the Ground Control Pro... spare no details, I can take it!

Re: noise problems

Posted: Tue Feb 09, 2010 5:57 pm
by buz
hey, thanks for the advice,
well i'll just tell you my whole setup:

Its usually a strat into gcx switcher, into a standard series loop of mxr dyna comp, digitech whammy (midi one), maxon overdrive, little muff, korg A3, pod pro xt, loop 7 is vacant, so its just patched. and 8 is a line6 verbzilla, i have a korg sdd1000 in an fx loop running through the pod pro xt. i have a separate power supply for the whammy, and obviously all the rack effects have independent plugs. I use some cheap power brick i got to control, my effects using standard 9v power cables that you plug into the brick.
Specification:
Power supply = 12Vdc, 1A
Output = 9Vdc, 100mA / outlet

I have been thinking of buying the voodoolab isolated power brick, if you think in your honest opinion that would make a difference.

all of this is connected, guitar in, then buffered out into the loops, ground control pro connected to the gcx, the 'out' of loop 8 goes straight into the in of my amp, which is a fender blues deluxe.

The pot switchers of the ground control is perplexing, since it is new, the pots can't be crackily already can they?

I don't know if thats to do with interference, because some crackle and some do not, and i'm not sure if its the actual pot or something else, i guess i could test every pot, and switch between programs and see.

I don't know much about ground loops etc. but I swear before this, i had a hum in my amp, and I moved a power strip like literally 10 cm to the left and it stopped, and the amp is on the other side of quite a large room! so any ideas on hums would be great, I have checked the loops of the rack effects, and their hum is a lot lower than the pedals, the pot as i remember for instant access 8 was particularly crackily.

all the best,

Re: noise problems

Posted: Wed Feb 10, 2010 10:42 am
by JohnClark
The Ground Control Pro does not process any audio... if there is noise when pressing buttons on the Ground Control Pro then the problem is elsewhere. If the noise is a crackling noise then I would have to guess first that it is likely some bad cabling. Try to simplify what you are switching by using Instant Access buttons or by creating some test presets that switch only one thing at a time. This will help to narrow down where the real problem is.

Wall wart power supplies can create noise in a system if they are too close to a sensitive device or again, bad cabling. Cables with inferior or failing shielding can let this noise in. Moving these types of power supplies as far away as possible is a good start and sometimes even rotating them can cancel out the noise. This is much like how single coil pickups will pick up noise from some types of lighting or a CRT type computer monitor, but if you stand just right the noise disappears.

Re: noise problems

Posted: Wed Feb 17, 2010 6:29 am
by buz
thanks for the advice, I have been checking my gear, and I noticed I can reduce the hum, if I lay the mono jack going from the out of loop 8 on the gcx to my amp over the power transformer powering the gcx if u get me? I noticed that hovering it around the transformer greatly increased/decreased the hum.
I got my transformer from a music store website that your company is associated with called, sounds great music in manchester.
could it really just be this transformer?

all the best

Re: noise problems

Posted: Fri Feb 19, 2010 11:09 am
by JohnClark
If the noise is coupling to the audio path because of the magnetic field of the wallwort/tabletop power supply, then relocating the power supply or sometimes simply rotating it, will usually yield a dead spot or null in the field and thus cancel out any noise. To first identify if this is in fact the main culprit, try getting it as far away from the rack and any cables. Listen for the noise to drop away as the power supply is moved further away from the rack.