Nobody sings their unsung salsa heroes like Puerto Rico, where rank-and-file musicians are known by name and “nostalgia” acts like El Gran Combo, playing their 45th anniversary concert this month, remain industry powerhouses. Salsa wells up from the ground here. Or perhaps it radiates from above: After all, in San Juan, my iPod was redundant, replaced by a cheap AM/FM walkman I wore everywhere, tuned to “Z-93,” the island-wide salsa station whose jingle en clave still sticks in my head.

I came to Puerto Rico to see El Dia Nacional de la Salsa, a stadium concert extravaganza paying homage to the living gladiators of the genre. Pedro Arroyo, Z-93’s program director, started the festival in 1984. “Salsa, at the beginning of the ’80s, was passing through a very difficult moment,” Arroyo told a Peruvian Web site. El Dia Nacional has helped promote salsa by watering the roots. Each year, Arroyo reunites historic groups and honors beloved performers of the music he calls “the people’s big party.”

For a $13 ticket, I thronged with 40,000 other salsa fans to a ’60s baseball arena in the sprawling commercial district of Hato Rey, wedged between a conservatory of classical music and Puerto Rico’s biggest shopping mall. The Sunday afternoon concert emcee’d by Z-93 DJs featured five named acts and legions of “surprise” guests. Papo Cocote and Montuno kicked it off, followed by vocalist Tito Nieves with two original members of La Masacre, Julito Castro and Ramon Rodriguez. Raphy Leavitt of La Selecta got emotional about the day’s honor, and his singer Sammy Marrero reprised the emotive “Payaso” and gave a contemporary spin to the anti-war message “Soldado.”

Luis “Perico” Ortiz, classically trained trumpeter and producer extraordinaire, came with two of his hitmakers, Ricardo Lugo and Rafael de Jesus. Puerto Rican-born saxophonist David Sanchez made an impromptu appearance, trading riffs with Perico on a jazzy comparsa that evolved into an all-out percussion jam featuring Cachete Maldonado. (Sanchez, who coincidentally flew on the same plane with me from Atlanta, was in town to premiere his epic La Leyenda del Cañaveral at Bellas Artes.)

But emotion and Puerto Rican flags soared to their greatest heights during the half-time salute to musica jibara, the traditional acoustic folk music of Puerto Rico’s highlands. Like dueling emcees, Victoria Sanabria and Victor Manuel Reyes (not the suave salsero, but a vociferous jibaro in T-shirt, jeans and trucker hat) threw down gauntlets in improvised verse, as cuatro guitarists Pedro Guzman and Prodigio Claudio engaged each other in a high-speed pluckfest. The coro proclaiming Puerto Rican identity surged through the crowd: “Jibaro Soy.”

Headliner Ismael Miranda took the stage as the sun set, and “El Niño Bonito” remarked on the refreshing breezes that cooled us. Nelson Gonzalez and Robert Roena, from Miranda’s shortlived but glorious Orquesta Revelacion, joined him as the night rocked to its close with tunes like “Ahora Si” (from the newly reissued 1973 classic Asi Se Compone Un Son). But the real spectacle was all around me: A sea of faces singing all the words.

The next day, fans called in their favorite moments to Z-93, still crackling from my walkman. A DJ summed up the mood with weary satisfaction: “I survived El Dia Nacional de la Salsa!”

Madrugador: Bio Ritmo

In this bodega in Richmond, Va., Hector Lavoe tunes and boogaloos by the Lebron Brothers are playing over the iPod stereo at 10:30 a.m. on an overcast Wednesday morning. Santeria candles and mirrors framed with hammered tin from old Café Bustelo cans adorn Kuba Kuba, a family-owned restaurant near the Virginia Commonwealth University campus. The front door is propped open. The blonde hardwood interior feels cozy, like the inside of a guitar.

“Voy pa’lla”I’m on my way, says Rei Alvarez, the lead singer from Bio Ritmo, as he delivers omelettes to a nearby booth. There’s no mic here, and no audience but the grill cook, but the words are the same ones Alvarez used the night before to kick off a rumba guaguanco.

Alvarez is working the morning shift after singing the night before at Emilio’s, a regular Tuesday night gig here in Richmond. Like most working musicians, Alvarez wears several hats to make ends meet, from waiter to graphic designer. In fact, the native Ponceño’s artwork graces the menus at Kuba Kuba, as well as all of Bio Ritmo’s flyers and album covers.

Drinking café con leche with my eggs with picadillo, I ask Alvarez and the trumpeter “Mambo” Bob Miller, also working behind the counter, about Bio Ritmo’s plans for 2007.

“Last year was a fairly busy year,” says Miller. 2006 saw the release of Bio Ritmo’s Jon Fausty-engineered EP, Salsa Sytem, and gigs as far afield as Chicago, Guelph and New York, plus an appearance on Puerto Rican television.

“I think it’s important, at this point, to play less gigs so that we can practice more and write more,” says Alvarez, leaving the door open to going back into the studio. “We have a lot of material we’ve never recorded.”

At the Tuesday night session, Bio Ritmo co-founder Jorge Negron (now a music educator at the Institute of Puerto Rican Culture in San Juan) sat in. Sets were expansive and experimental with new tunes I hadn’t heard six months ago.

In a nod to tradition both gutsy and whimsical, Alvarez added a bolero to his setlist by Bienvenido Granda, “El Bigote que Canta” (literally, “the mustache that sings”). Alvarez sports a ‘stache himself these days, but one that evokes leather biker more than bolerista. In between live sets, Alvarezaka DJ Rattanspun Puerto Rican vinyl from the hot 1970s, bands like Impacto Crea, Bobby Valentin and Roberto Roena. Fitting, as that’s the furnace of the Bio Ritmo sound.