The guys on 'That Pedal Show' put out a half decent YouTube video a year ago about powering pedals... They had an acronym of VCPI being Voltage Current Polarity Isolation...
Voltage and Current are pretty self explanatory, as is Polarity, but I was a little disappointed in their explanation of the whole Isolation thing. Earth loops and appliance noise isolation are two completely separate issues yet both can give the same audible effects, and the guys video seemed to overlap the discussion of the two issues particularly as both are minimised by 'isolation' for very different reasons.
Using one power board to do both input effects and effects loop devices opens the door to creating an earth loop that runs from the input jack to the effect then on through the power board to the effect in the effects loop and then back to the amp via the effects loop cable. A huge circle of earth wires so to speak. Very bad for noise and hum.... If noise and hum are an issue then the simple solution is to separate the power of the input and the effects loop effects thus breaking the 'huge circle' with Earth on the the amp as a common 'star point' for all Earth's.
Then there is noise induced from one effect to another... Digital noise is present on the power rail of virtually every digital effect pedal, and this noise often gets into adjacent analogue pedals via the power lead. Usually it comes in via the actual voltage rail but it can also jump into pedals via the power cable earth. The solution is to isolate each pedal to its own 9V or 12V or 18V regulator such as found in many 'isolated power boards' although the design of the power board in some cases leaves much to be desired. Usual affair is to use a bunch of 7809 100mA regulators and maybe a LM317 for the 500mA socket which will work well only if there are the appropriate electrolytic caps surrounding the regulator IC's. While most are pretty good there are some power boards that have these caps missing or the wrong value while others over compensate with 'extras' for near nil tangible benefit.
Yes, it is better to put your digital pedals on separate power supplies to your analogue pedals, and it's better to have separate power supplies for your input effects and your effects loop effects.... but if you can get away with and have nil nose/hum using only one isolated power supply board for all your essential and much needed effects then lucky you... Luckier still if you suffer nil hum/earth loop issues all you are using is a simple pedal to pedal jump cable.... Way back when in days long gone where a Fuzz and a wah and a boost/OD was all that existed a simple jump cable was all that was needed...
For reference, my digital effects are from TC electronic, Digitech, NUX and CatalinBread, and analogues are from Ibanez, ElectroHarmonics, Dunlop, Behringer, Joyo and my workshop bench...
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