Pedal power supplies - anyone getting noise?

Ant1981 · #1 02-08-2006, 10:13 AM

Hey,

Does anyone know why I would be getting a hum through the amp when I use the same power supply to power effects in the effects loop and the effects in the amp guitar input?

If I unplug the power from the effects in the amp guitar imput, use just a battery and leave the power supply for just the effects in the effects loop, then everything is fine, no hum. Why would this be?

Have been considering getting another power supply for the pedals that go in the amps guitar in, keeping both supplies seperate

wildchild247 · #2 02-08-2006, 10:37 AM

yeah I got the same problem

but i think it could be my pedal because it is not a true bypass

I am asking a tech about it and he is still working on it

rgr · #3 02-08-2006, 12:09 PM

The hum is in all the effects, it's the filtering, or lack of filtering in the power supply. The reason you only notice it in the effects in front of the amp is that the preamp amplifies the signal coming in so much that amplifies the noise to an audible, and often annoying, level. I'm assuming that you are using a Boss or similar adapter.

There are a couple of things you can do, the best option is to get a better power supply, the Voodoo Labs one is nice, but expensive, the Visual Sound 1-Spot is good, http://www.visualsound.net/1spot.htm, it uses a digital switcher to generate the DC power, so it still introduces some noise, just not the 60 cycle hum, its noise is very high frequency and may not even come through your amp, I use those and also have a LR (inductor/resistor) filter that I built in line before my front end pedals.

There are also some schematics out there for good linear power supplies, if you are handy at that sort of thing, but you'll probably spend more building one than the 1-spot costs though. You are also hooking up a 120VAC wall circuit, so care needs to be taken.

Roger

Ant1981 · #4 02-08-2006, 12:12 PM

No, there is no noise at all when the power supply powers ONLY effects in front of the amp, there is only noise if the supply powers up front effects AND loop effects.

flarocks · #5 02-08-2006, 12:46 PM

I know I may be shooting in the dark here but when I got my pedalsnake I had the same issue and you won't believe what the solution was. With any of my analog effects, I had this interference I couldn't get rid of. I was using the boss psa-1 (standard supply?) and a 1.spot to power the rest. The folks at morley actually solved it for me. You need to keep those warts as far away from the effect they are powering as possible, they are not shielded! Moving the power supplies off the board cleared up all the noise in my system.....everything!!!!!!

Ant1981 · #6 02-08-2006, 12:55 PM

Thats not the problem, the problem is exactly as stated above, but thanks anyway dude.

rgr · #7 02-09-2006, 07:57 PM

Quote:

Originally Posted by Ant1981

No, there is no noise at all when the power supply powers ONLY effects in front of the amp, there is only noise if the supply powers up front effects AND loop effects.

Sorry, I missed this before.

What effects are you using and what kind of power supply are you using? It could be possible that you are trying to draw too much current from the power supply. Of course, without more info I am shooting in the dark.

Roger

ChopTart · #8 02-09-2006, 08:09 PM

Not to hijack the thread or anything, but which power supplies will have an AC outlet in addition to several DC ones? I want to keep the Big Muff in the chain, but it uses AC unlike my crybaby and boss pedals. Ideas?

bduersch · #9 02-10-2006, 04:25 AM

Sounds like a classic ground loop issue to me, since the problem goes away when batteries are used on the pedal out front. Using a different power supply may help, hard to say. You also might want to see if your amp has a "ground lift" switch on the back. If neither of those work, you may want to look into a Hum eliminator device. Ebtech makes a decent one... I had one in my Mark IV rig a couple years ago b/c some combination of powered pedals, rackmount FX units, and the amp caused a vicious ground loop, that could only be taken care of with the Ebtech.

--B

Ant1981 · #10 02-10-2006, 01:06 PM

I'm not drawing too much current, as an overload protection device would activate, this being the fuse.

Pedals up front are Cry Baby, MXR Super comp

Loop pedals, MXR micro amp, MXR EVH phase, Boss DD-6 delay.

I'm going to have to try using seperate power supplies for each group, as when the power supplies one group at a time with no noise, and only noise when supplying both, then a seperate supply might cure it. Just need to find another one before I buy one.

rgr · #11 02-10-2006, 03:04 PM

I really hope your not thinking about the circuit breaker for the wall outlet! If you are using a standard Boss type power supply, I don't think those are fused, and if is one of the 200mA versions, you might be pushing it's limits.

Brad has a really good point too, could be a ground loop.

Ant1981 · #12 02-10-2006, 10:37 PM

No I'm not drawing too much current, or talking about the circuit breaker. Being an electrician, I've ruled that one out.

It's gotta be something to do with sharing supplies for preamp effects with loop effects. So I'll have a go with two seperate supplies and see how I get on.

rgr · #13 02-11-2006, 02:29 AM

I thought so, but sometimes you get some strange posts here. Sorry, didn't know you were an electrician.

megadeth · #14 02-11-2006, 02:48 AM

I have same problem. I plan to move out of this house.
seriously. actually, I'll move out once I get a job..so I am not bothered.

red5 · #15 02-11-2006, 04:51 PM

The problem is simple. Plug the effects into a different fuse or circuit than you plug the amp into. It's called 60 cycle hum. The amp and pedals operate on the same frequency so they interfere with each other. Most pedals do not have this problem, but some do. The Soldano Supercharger is notorious for it, and even the company tells you not to plug it in the same circuit.