Burning Amp Sizzles in San Francisco

It was no accident that home remodeling architect Mark Cronander, aka Variac, scheduled the Sixth Burning Amp DIY Fest for October 28, on the same weekend that the AES Convention (Audio Engineering Society) took place in San Francisco. Not only did Cronander attract a fair number of new folks who came into town for the convention, but he also scored, as a speaker, class-D amplification expert Bruno Putzeys of Belgium's Hypex Electronics.

Burning Amp drew close to 200 people to talks by Putzeys, Nelson Pass of Pass Labs (a universally admired champion of the DIY movement), and DIY designer Jan Didden of Linear Audio. Occupying an entire floor of Building C at San Francisco's Fort Mason Center, which abuts San Francisco Bay, it also offered a host of active DIY displays in its five exhibit rooms, including systems from Pass and speaker expert Siegfried Linkwitz, and some down home barbeque.

"My neighbor at Sea Ranch, Jerry Immel, who composed the music for Dallas, built the speakers," Pass told me in his room. The speakers, which had Lowther PM6 drivers with field-coil magnets, open-baffled, slot-loaded Eminence Definimax 15 woofers, and, as best I can make out from my notes, a B5 crossover, were driven by DIY Turbo and SIT2 First Watt amplifiers.

"Any amplifier that can output ½ watt can drive the top end, and anyone who has brought their own amplifiers can hook them up later this afternoon," Pass told me. "That way," he quipped, "everybody's gonna think the system sounds great."

Among the admirers of Pass and Immel's system was Dusty Vawter of Channel Islands Audio. "I've always been a Nelson Pass fan," he said. "It's great that he supports the DIY forum, and has helped see the community expand with so much enthusiasm. DIY has turned into a career for me."

Across the hall, Sydney Ma (Syyme) of Castro Valley, who works as a technician at a luxury car dealership, showed off a bi-amp system that included his own preamp and open-baffle speakers. "I spent $40 for the 15" woofer!" he proclaimed. "You can't go wrong." Next to him, Stefan Georgiev, an Application Engineer for a semi-conductor company, displayed the first fruits of his fledgling business, Acoustic Wavefront, which specializes in "art oil on canvas designer level sound quality improvement devices."

Jon Lindor of Slough House, CA (pop. 150), who maintains the radio system for the Sacramento Sherriff's Department, demmed his first hand-built 60W "Wire Hell" MOSFET push-pull amp. Built from a circuit he found online, the amp included surplus parts, Radio Shack boards, and transformers he found at a medical supply company. "I love analog meters," he proclaimed. "My main reason for coming was to meet Nelson Pass. Rather than come empty-handed, I built this." Anyone wondering what "Wire Hell" referred to needed only take a deep breath and look inside.

Burning Amp regular Siegfried Linkwitz of Linkwitz Labs demmed his latest speaker experiment. Dubbed the LX 521 because Linkwitz had "a key midrange breakthrough" on May 21, its very attractive open-baffle housing is called "Form Follows Function FE," and was inspired by Bauhaus.

"I wanted to build a speaker that has a good dipole radiation pattern with less deviation than before," Linkwitz said. "I wasn't initially concerned with looks, but I think it turned out okay." The cabinet's red hue was to match that of the Golden Gate Bridge, which could be seen out the huge room's side windows.

Linkwitz, who sells his construction plans online, noted, "I've found that there's an honor code in the DIY community, of which I'm very proud. People recognize the value they get for little outlay; they don't illegally sell or trade plans." Not too long ago, after members of the DIY community informed him that a company in England was ripping off plans for his Orion loudspeaker, he put them on his online blacklist, and word spread like wildfire. It didn't take long for the company to cease and desist.

Linear Systems, which manufactures many of the discrete JFETs popular amongst DIYers, helped make possible the snazzy red Burning Amp T-shirts for sale. Vying for attention with the free cheese and crackers on the other side of the guest speaker room, the shirts helped frame Cronander as he introduced Nelson Pass, "whom I think you all know. Burning Amp wouldn't be what it is without Nelson."

Pass' well-illustrated talk, "Amplifier Design in the Post-Modern Era," explored the design of his recent F6 amplifier, and the importance of the 2nd order harmonic in tuning an amp's sound. One of his best lines: "There are lots of nice parts out there, and they may sound better, but they're not cheap, and DIYers are cheap. Besides, if it sounds good with cheap parts, then your design gets all the credit."

Because of limited time, I skipped the other talks and returned to the exhibits. Kolto, who otherwise does AV editing and sound recording at Cable 26 in San Francisco, showed his big Zen Acousta Field Coil Driver loudspeaker. Claiming a sensitivity of 103dB, it was driven by his own electronics, which used a friend's custom-made transformers.

Bryan Levin of Sercona Audio in Santa Clara broke into a big smile. "My photo in Stereophile two years ago helped launch my business," he said. Levin must be doing something right. No less a personage than digital expert Demian Martin (Monster/Constellation/Auraliti) has been drawing on Levin's expertise with computer remote controls to perfect the user interface on the new Auraliti L-1000 music server. "He's a whiz with networking," said Martin.

Bill Mennuti, a food scientist at General Mills (as in "I make Cheerios"), showed the same Metronome enclosure speakers that he brought to Burning Amp I six years earlier. Although he acknowledged that the room acoustics were less than ideal, he said, "We get the venue we can get and make the best of it. Here we have plenty of room, and if we make noise, no one complains."

Across the way, software engineer Ti Kan of Sunnyvale, who publishes his designs at amb.org and sells circuit boards and parts, was playing kit-built Audio Artistry CBT36 loudspeakers designed by Don Keele. With MDF cabinets handsomely painted at a bodyshop, he used electronics from Benchmark, Behringer, and Hafler, and cabling both handmade and by Monster Cable to achieve some of the best sound at the show.

I caught up with Cronander, chief organizer of all six Burning Amps, near show's end. "We're heartened by all the new people in their '20s who have come," he said. "We again held our annual Amp Camp at the Brock Family farm in Sonoma County. Nelson donated components, and the average age of attendees was 25. People feel that making something themselves has greater value than buying it pre-made."