The Joyo Ultimate Drive is a clone of the Fulltone OCD. It is a very dynamic overdrive. The Joyo Ultimate Drive sounds great unmodified so there is no need to learn to solder just to fix it, but to my ears it sounded a little dark and harsh pre-mod and much improved after.
However the small difference in sound is probably something that most people won't even notice. But if you're a very detail oriented pedal nerd, like me, there is a mistake on certain pedals with a PCB that reads 2010.11.24. Specifically D2 (Diode 2) on the PCB is backwards even though the mask on the PCB shows it to be correct, There is a discussion here, on freestompboxes,org, that gives more details.
Diodes are used for clipping and circuit protection in stompboxes and generally only allow electrons to flow one way, the symbol with the arrow shows the way the diode is meant to go on the PCB, and in this case the it was the image that was wrong on the PCB , as the diode was soldered correct based on the image, but since the image was wrong, the diode was not really doing its intended job of clipping the audio signal from the guitar and giving you that lovely imitation of a dynamic tube amplifier. However in practice, the difference to the listener is rather small, so watch my video and you can be the judge!
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