M800 and Golden Folks Overdrive hum at 18v (no hum at 9v)

[sbn31]

Hi, i tried running my M800 then my Golden Folks Overdrive on a 18v-2A dc switching psu (brand Rockpower) and i get the same drone hum when the effect is on. These 2 pedals are based on 201 jfet (thru hole no smd).
- There is no hum when running these 2 pedals at 9v.
- The PSU is new and I get no hum when powering an Aion Titan (OCD).

Any advices ?
Many thanks !

 

[jwin615]

You'll probably have to rebias it to get it to work at 18V.
Are you playing an active bass with super hot output? why do you want to run it at 18v?
Fet circuits aren't like other circuits that rely on a simple voltage divider or inverter and can run at 9-18v without issue(TS style).
Also, I'd recommend against just running 9v pedals at 18v unless you know it's cool. I've seen plenty of production pedals with power smoothing/filter caps rated near or under 18v. Some rated for 10v(looking at you Peavey)

 

[jwin615]

It may also just be a crappy power supply. Not all equal. Far from it.
Try it on something designed to run on 18v.