Lovers and luthiers alike could learn something from Aaron Grad’s grand passions.

Grad, a Seattle-based composer and jazz-influenced experimental musician, appears this Saturday (June 21) at the Chapel Performance Space in the Good Shepherd Center with an evocative program called “Old-Fashioned Love Songs.”

If that title suggests a lost era of sunny crooners and kids sharing malteds, Grad has broader, more immediate glories in mind. “Love Songs,” among other things, is the fulfillment of two key quests in his adult life, the first concerning heartfelt communication and the other a sound.

“I wanted to put to words and music a full expression of love for my wife and partner of many years,” says Grad, 33, a Virginia native who earned his master’s degree in composition at Johns Hopkins’ Peabody Conservatory. He’s married to Jen Kovarovic, a Suzuki violin teacher. “I’ve tried lots of little ways previously through poetry and cute pop songs. But those never quite spoke with the full intensity of what I was trying to say.”

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The answer came from a 21st-century update of a 16th-century instrument: the theorbo.

A deep-bodied lute with a giraffelike long neck and 14 strings that allow for extended bass range, the theorbo was developed for basso continuo parts broadly used in the Baroque era. When Grad encountered one at a Brooklyn production of Monteverdi’s 17th-century opera “L’Orfeo” a few years ago, he realized the huge bottom end he had been seeking on a string instrument was in the theorbo.

“I always wanted a wide, expansive range in the music I write and perform,” he says. “As a guitarist I was limited. But I became transfixed by the theorbo and merged its template with my sound, which is the electric guitar.”

Going electric on an instrument from Bach’s time was no easy task.

Grad ran a Kickstarter campaign to raise money to buy the specialty tools needed to build what had never been built before.

“The tricky thing was the physics of it,” he says. “Part of the reason the theorbo’s neck was so long was that it used low-tension gut strings. I wanted to preserve that visual aspect but got into problems with materials because I was using steel strings that have much higher tension. I ended up using carbon fiber, ebony, walnut, maple, black limba … whatever could structurally support the strings. Then I had to figure out how to make it all stay in tune and not be ridiculously heavy.”

When he was done, Grad knew he had found in the electric theorbo a “perfect vehicle” to express both his personal and universal experiences of love.

“The instrument gave ‘Love Songs’ a sense of timelessness, because it gave me access to old sounds and old ideas about love.”

“Old-Fashioned Love Songs” is a cycle alternating 11 of Grad’s original compositions and poetry with five centuries of songs by composers ranging from John Dowland to George and Ira Gershwin to Cyndi Lauper. In essence, Grad will be accompanying his vocalist, countertenor Augustine Mercante.

“The concert begins with the personal and becomes a wider, broader meditation on love,” Grad says. “The second half is a tear-jerker, very sweet but taking love all the way to the end, to inevitable separation. It’s an uncomfortable but emotionally gratifying place to go.”

Tom Keogh: