I see that people have had problems with the polarity reverse plug CYR. I am using onespot CS12 with an H9 and it powers nicely. This plug goes into the adapter port of the H9 and then attach any regular power cable (negative center post) and it works great. The other may have been a 2.5 mm plug for some odd reason

I bought this adaptor hoping to run my Eventide H9 pedal off of either my Dunlop Brick or a One Spot wall wart (depending on the actual mA draw of the pedal), as the wall wart that came with the unit recently ceased to work. Unfortunately the barrel of this plug is slightly too large to fit into the H9 power input. I"m sure it"s a good product, but not the one i was looking for.

Did not work with Fulltone soul bender fuzz pedal. It turns on a nd works only by itself, As soon as itiis connected with the other pedals..using 1 spot power supply , everything shuts off. Polarity issues linger , I have no use for this adapter . I bought 3 .

I use these to reverse polarity on a power cord patch cable that came with my Truetone 1 Spot power supply. One of the adapters that comes with this power supply is for powering a pedal that only has a 9V battery connector. I wanted to use that adapter the other way around - attach it to a battery and then power a mini pedal that has no battery compartment. This polarity converter did the trick. Now I have a way to power any 9V mini pedal with a battery instead of using a full on power supply.