How to use mobile powerbank as power supply

Hello everybody, I would like to share how to use mobile powerbank as Beatbuddy power supply.
I am using USB 5vdc to 9vdc converter that I bought from Amazon and connected to my 10000maH powerbank and Beolit 17 speaker . You need to cut the USB cable to change the polarity to match the jack power on the Beatbuddy. That’s it, now you ready to play all day along with your Beatbuddy with more freedom. This system is very good for outdoor activity just like camping, picnic, family party… etc…etc…

Reverb has the wire already reversed polarity