Nashville's West End strip is the crossover capital: a line of fast-food neon and pretentious "ethnic" restaurants running between Music Row - the shoulder-to-shoulder blocks of recording studios and country music publishing firms - and the rock clubs and boot-store hangouts of the Vanderbilt students.

One of these all-night eateries, a glaring box of bathroom-white tile and chrome, is the Krystal, part of a chain of hamburger joints in the Southeast noted for respectable coffee and perfectly square burgers to small they are often consumed by the dozens. The Krystal is the spiritual home of thousands of under-30 Nashvillians: it is also, according to legend, the source of Crystal Gayle's stage name.

Crystal Gayle twists her mouth sideways and wrinkes her nose. "I'll never live it down," she says, and then laughs, knowing she'll never really want to.

Crystal Gayle: Born Brenda Gail Webb, the last of eight children ("I always thought I must have been a mistake") and the prettiest - willowy under her hip-length veil of hair and with a traingular cat's face dominated by pale blue eyes and circumflex brows; twice Country Music Assn. Female Vocalist of the Year and Grammy-winner for "Don't It Make My Brown Eyes Blue": one of the handful of country artists to have an album go platinum (sell a million copies): a figurehead of the "crossover" movement; nearly 20 years younger and a culture away from her traditionalist country-queen sister, Loretta Lynn.

"We're pretty close for being . . . apart," says Gayle. "We don't see each other all that much."

Loretta Webb Lynn was already married and had "a couple of children" (Gayle is bad with numbers) when her baby sister was born. Lynn and the older siblings were hill-country children, educated sketchily in one-room schoolhouse and married young - in Lynn's case, at 13.

But Gayle was the child of her parents' slightly more comfortable middle age. Born in Kentucky, she moved with her family to Indiana at 4, into a small-town life "where the school had lots of rooms." Like many country music artists, she began by singing in church; by high school she had already recorded a number of "demos" and one song.

In her separate world, Lynn was working her way up the ladder into the Nashville scene through a series of down-to-earth songs such as "Coal Miner's Daughter" and the hands-on-hips classic, "Don't Come Home A-Drinkin' With Lovin' on Your Mind." And by the time Gayle graduated from high school, Lynn had enough pull with her record lable (Decca, later MCA) to get little sister a contract.

But Decca already had one Brenda - Brenda Lee - and so Lynn christened her sister with the exotic name from the all-night grill.

"The only reason I was on (Decca) was because of my sister, and everybody knew it." But Gayle wasn't writing the same idiom, or singing to the same audience.

Loretta Lynn from Buther Holler has remained a plain-spoken, religious, sunrise-to-sunset country woman. Her hair is still teased a little on top: she wears old-fashioned ging-ham dresses with high bodices and ruffles. Like the character in Altman's "Nashville" probably modeled in part after her, Lynn has worked herself to the point where fatigue threatens to become collapse. She stirs primitive and sometimes violent emotions in her steadfast following: she has even faced death threats.

Crystal Gayle of Wabash, Ind, wears fashionable earth-toned makeup, satin pants and spaghetti straps onstage - sometimes even jeans, like the French denims with rolled-up cuffs. There are no lines around her eyes left from earlier, hungrier years.

She doesn't wear false eyelashes. Her hair is straight and is dressed, not elaborately, in braids. She has played the Roxy Theater and the Bottom Line; she didn't even move to Nashville until after the Grand Ole Opry had left the Ryman Auditorium for its spanking-new digs at Opryland.

Loretta's songs demand stright talk; Crystal wants sweet words.

Tell me no secrets, tell me some lies. Don't give me reasons, give me alibis.

Tell me you love me, and don't let me cry.

Say anything, but don't say goodbye.

1977 Big Three Publishing

Photogenic, cool-headed, on the crest of a series of hits and honors, Crystal Gayle is the obvious target for country music purists who fear "crossing over" into pop music may weaken Nashville's powerful position as the country music capital.

"To me, I just consider myself a singer: "I don't like labels. 'Brown Eyes' was more than a crossover, it was a huge song everywhere. As far as benefiting from it . . . well, it has opened some doors for me.

"I don't label someone by songs they sing. If I want to sing a country song, I do; if I want to sing a blues song, I will.

She, her law-student husband and the band have spent four out of the past five nights on their rented bus. She is tired, although her eyes are clear; her hair is damp from a shower and she wears minimal makeup. She is taking the evening off before going into the Cellar Door tonight.

As a photographer circles her, she drags her hair away from her eyes. "I don't take really good pictures. I've done a lot of sessions in Los Angeles, and they must be into shooting a lot of models - they want me to do this, and that," spreading her arms in an exaggerated version of a high-fashion pose. "For the new album, 'When I Dream,' I had everything sent to me. I picked the front, the back and the middle.I wanted to be that I wanted to see."

She is very businesslike about herself as a product. She projects a kind of Kate Jackson image: streetwise, jargon-hip, sexy-clean and straightforward. She is her own manager, and she keeps her career on schedule.

"Right now I'm into the music," she says, "but I love television work. It's more one-on-one: you're going into someone's living room and you don't have to try to project the back of the auditorium."

She's had offers of her own show, and she "can see a special of some sort." But slowly; "I don't want to be the kind of person who goes out to do a new thing and can't do it right."

In the meantime she's enjoying the high visibility of magazine covers like People and Country Music. "I don't mind people asking for autographs - I'm flattered. It is kind of funny to go shopping.I love just looking, and all of a sudden there are all these people looking at you !

"But when I get home, that's when Crystal Gayle stops - there'll be no autographs signed at my home."