This model was designed to be used on 3 channel organs, with the appropriate console connector kit.
The 615 features 2 rotors and a total of 8 speakers, including 2 actual tweeters on the stationary channels. This is a vast improvement over earlier models which had only 6x9s in their “keyboard” channels, this model still has the 6x9s but also adds a high pass filter and a tweeter for brighter highs.