We don't have a lot of details about Joe King. According to an online post, he played guitar on some of the Harmonic Sounds productions, and was not very active as a live singer. He has a good enough voice and fortunately he was given a chance to release a 45 of two of his songs. "Speak On Up" is a nice bouncy throwback Motown styled song that might have been a regional hit if given better promotion.
The same online comments claim he joined the Crowd Pleasers, although he is not credited on their LP.
What's Wrong / Speak On Up - Prix 7002, 1970