Reliable 9 volt Guitar Pedal Power Supply
One Spot by Visual Sound
Once I was surprised why my distortion pedal Boss DS-1 makes a lot of noise on a higher gain. I used to think that the pedal was noisy itself and there was not much I could do about it.
One day I was experimenting with my effect pedals and put a 9 volt battery in the DS-1, and voila the noise was gone. I've only heard a little hum with the gain knob all the way up, but this is normal. It happens with almost any distortion pedal due to their nature.
When I experienced the problem it was with my 9v DC adapter.
It was a regular, cheap DC adapter that I used with a multi-plug cable to feed a few effect pedals simultaneously. Strangely enough all the other non-distortion pedals were working just fine, as well as the digital effects processor on overdrive and distortion settings.
I went to a music store to ask about a DC adapter that could filter out the grid fluctuations or whatever was causing the problem.
The salesman advised me to get a 1 Spot power supply that was designed specifically for feeding guitar effect pedals.
I bought the item, went home and plugged it in.
The problem was solved immediately. On the highest gain the distortion was making as little noise as with a battery inside.
The other nice things I liked about the One Spot, are that despite its size (about the size of a cellphone power supply), it provides up to 1700mA of electric current. While my older adapter was making just 400mA.
Each guitar effect pedal usually eats about 50-100mA, and digital multi-effects processors around 300-700mA. That means 1 Spot can easily feed 10 pedals and a serious digital effects processor simultaneously. (Assuming the processor consumes 9v. and has the same slot for power connection as on the guitar pedals.)
Note that in order to use a 1Spot guitar pedal power supply with a number of stomp boxes you'd need to get a multi-plug cable. (Also called 'daisy chain cable').
Keep in mind that while this adapter fits the vast majority of pedals on the market (Boss, Danelectro, Digitech - X series, DOD, EBS, Ibanez, Marshall, Zoom, Nobels, many Electro Harmonix, MXR pedals, Roland Micro Cube amp and a lot of others...), there are still some pedals that use another voltage and/or different connection that you can't use with One Spot.
For instance Blackstar HT pedals need a 16 volt AC adapter, Electro harmonix Delay Memory Man - 24 volt, MXR M108 10 Band EQ - 18 volt and MXR Doubleshot Distortion - 12 volt AC...
1 Spot guitar pedal power supply can convert international voltage (100V-240V) automatically with no transformer needed. However you'd still need to obtain appropriate end plugs that fit the sockets in a country you're going to visit.