Traditionally, people sang melodies written by Kabbalists, in sad minor keys. But we must understand that every Kabbalistic melody is above the Tzimtzum, meaning above concern for oneself.
All the melodies are directed towards the Creator with a yearning to adhere to Him with bestowal and love, to give Him contentment, and to resemble Him in one’s relationships to other people. They don’t express regret about the hardships and suffering, or complaints about the difficulty of life, as is commonly understood in religions.
Concerns like these and the general sorrow of a person are not mentioned in the wisdom of Kabbalah and in the books of Kabbalah. This is because the Kabbalists are in a state that is beyond the Machsom, in the borders of the spiritual world; therefore, they take no account of themselves but only the Creator.
And if they are sorry, then it is only because they cannot achieve more devotion and self-sacrifice for the Creator. All thoughts, desires, and expectations are directed outside of a person, and this should be felt in the melody. This song is an outburst and enthusiastic outpouring of the soul.
If we sing a melody by Baal HaSulam, we must imagine his state and try to be as close to it as possible. Otherwise, we associate this melody with our physical state, to our crying and requests: “Give, give, give!” We transform the sacred into the profane.
From the Preparation for the Daily Kabbalah Lesson 5/20/14