"I am a hopeless romantic / And I'm full of pretty lines," Melissa Ferrick sings on her 2001 album Valentine Heartache. That tells you a lot about Ferrick as a performer, but not the best news: though her albums can be spotty, her live show is terrific.

Three years ago, I left a Ferrick show totally drained, excited that one singer and acoustic guitarist with a drummer could match the intensity of a great rock 'n' roll show. A coworker I saw there raved about her too — but by the next week, she'd bought a Ferrick CD and hadn't liked it at all.

How can that be? Well, a lesser Ferrick lyric reads like a raw journal entry: wounded rants or pop philosophy, righteous but unpoetic. Ferrick's voice ranges from plaintive to brittle; her writing is angst ridden and earnest, her guitar strumming manic. On CD it sometimes seems overdone, as if she's reaching out of the speakers to grab you by the shirt and shake you.

But in concert Ferrick has a great presence, charisma, and connection with her audience. Her personal manifestos resonate, and her angry relationship songs turn cathartic when the fans sing along, consoling and consoled. And when Ferrick breaks into her best songwriting, when she finds a structure to carry her emotion, each line holding more power than the last, her guitar work flying faster and faster, it's thrilling, one of the best buzzes you can get from an acoustic-guitar slinger — as in this chorus:

Go ahead and tell your friends
It was a one-night stand
Tell them you were out of your head
Tell them we never made it to my bed . . .
But don't try to tell me
You didn't look in my eyes and say to me
Don't let go!

Ferrick's brief time on a major label, Atlantic, resulted in one overproduced album, 1993's Massive Blur, and one charming album full of signature songs, 1995's Willing to Wait. Now, she releases albums on her own Right On label. Valentine Heartache is probably her best: it shows off her versatility as a guitarist and the sharpest variations on her favorite themes. But Ferrick seems to realize she's at her best in concert. Her new CD, 70 People at 7000 Feet, is her third live album.

Even more than most singer-songwriters, Ferrick's (and her fans') biggest dilemma is how to sustain a musical career fueled by romantic turmoil. "I'm sick of writing this song / About how love always disappears," she sang toward the end of the show I saw. So I'm happy to report that her last studio album, 2002's Listen Hard, finally proved she's equally talented at writing sweet, optimistic love songs. Let's hope that whatever relationship she was singing about is still going strong when she visits the Ark Sunday, April 18.