So, what is all this hype about "King David's Harp?" There are at least 3 subjects associated with that phrase.
First, it is a brand name of harps (a maker).
Second, it is a mode of specific tunings not associated with the current orchestral standard of A:440 Hz.
Third, it is a type of stringed instrument assumed to have been played by ancient Israel's King David & later by his Ark/Temple worship teams eventually to be led by his throne-heir, King Solomon.
Let's look at #1: It's more or less a brand name used by a specific manufacturer of lyres & harps. Other makers also try to make use of this moniker for their specific, harp-like stringed instruments.
#2 is rather a modern, New Age-ish term for setting musical instruments to tunings based on any other frequency than A:440, which is often suggested was the 1930's German Nazi regime's forced standardization of orchestral tuning; having allegedly evolved from the prior, universal A=432 Hz tuning.
It is suggested that A:432 provides an uplifting, relaxing spirit when listened to, aligning the human body & mind with the universe. While, Hitler's occultist, "negative" A:440 tuning introduced tension & uncertainty; qualities many feel should not be associated with the goal of all music.
But, it should be understood that A:432 was not The Universal Orchestral Standard many assert. When studying old music & associated instruments created to play that music, we find many different foundational standards, right up to modern times; not just 432 Hz.
By the way, Hz is an abbreviation for the term, Hertz. Hertz was a scientist credited with naming the process of how sound vibrates and how it can be scientifically analyzed and understood from the aspect of certain physical properties. Musically speaking, Hertz is basically how many times a second any certain musical note vibrates in free space.
For instance, piano middle C vibrates 256 times in a single second; each complete vibration called a "cycle." Frequency means how many cycles per second (Hz) a sound is generated by; how frequently over time a plucked string vibrates to produce a certain sound (musical note).
Proponents of such Frequency draw upon the Universe as a living entity (more or less) and its assumed ability to use innate vibration (Frequency or Hertz) to heal, motivate, lead, inspire, or perhaps to realign humans with their true creation or evolution, etc., using various "positive & higher" frequencies as the foundation for music.
One example is the tuning of 444 Hz for A is said to promote "healing of the body." Another frequency might promote mental health. Another, to assist in spiritual meditations or even in transitions from this life to the next, etc. (This is big in the clinical harp industry.)
#3 is the research done by certain Musicans (not misspelled) that say King David's harp was actually a lyre, not a harp as we know it today. While this may be true, many dogmatic opinions can be found all over the scale as to what actually were the "harps" & "pipes" King David & his worship orchestra created & played.
All we have today are mostly opinionated assertions based on Evolution rather than facts. That is, we only have a sketch or two, and few engravings of what such harps may have looked like in the ancient past in the land of ancient Canaan. Mostly, what King David may have played upon come from associated time periods from such art found in ancient Greece, Mesopotamia, Egypt, etc.
It is reasonably assumed David played a form of 10 note stringed Lyre. That he played a harp, the vision of which we harpists & makers assume appears as our modern, resurrected types of folk harps comes from the inadequate term found in the old & outdated King James Version of the ancient Judeo-Christian Holy Bible.
And, it is understood that David & all his musicians made their own instruments & learned to play them as such. This is a wonderful idea that we today can replicate by making our own instruments, such as using my harp kits for yours.
Moving on: it is often pointed out how King David played for his King, Saul, when the king was in mental distress via some form of demonic infestation. David's playing would temporarily deliver Saul from his God-sent, demon agonizers.
So, it is assumed today, especially within the clinical harp movement & within the modern charismatic Christian and New Age movements that such sounds (Frequency) can deliver & heal. (That the player is using God's embedded universal Frequencies is relying upon New Age/Alien Federation thinking.)
However, others suggest, theologically, that King David was likely delivering Saul via a one-off miracle; not something that can be replicated today by simply playing at any certain fundamental frequency (that is, only God can heal & deliver through His Christ, that the mere physical properties of post-Edenic, fallen physics & humans cannot).
That such healings., etc., are possible today has its roots within modern New Age spiritism mixed with either mystical Christianity, or the Jewish Kabbalah. It is well beyond this Blog to suggest whether one's spiritual practices are "correct" or not. Merely, I want to fill in the gaps of information that certain of my clientele have been asking about this particular subject matter. From here, you decide what is best for your faith.
None the less, I pray you & others are richly blessed in your music, regardless of approach; especially your harp music.