Groove Crush Weiss’ record collection is big. Conservative count: 12,000. His go-to reference discs for setting up a turntable system are Será Una Noche and La Segunda, both produced by Santiago Vazquez and Todd Garfinkle. In the jazz stacks, “Mood Indigo” from the reissue of Masterpieces by Ellington, paired with “a good mono cartridge,” gets a lot of play. Those giant horns, an OMA signature, are designed to work with Weiss’ low-wattage triode tube amps.

This Old House Oswald’s Mill is a four-story, 10,000-square-foot house-mill in scenic Lehigh County, Pennsylvania. Brawny German immigrants used to grind flour here between massive millstones. Built around 1800, it’s now the only known house-mill left in the country. All these things about the mill—its immense size, secluded setting, and historic significance—appealed to Weiss. So he bought the place and electrified it. As it happens, those 2-foot-thick stone walls make it the perfect lab for developing audio products.

Movie Muscle Long before Quentin Tarantino needed special film projectors for The Hateful Eight, Walt Disney needed special amplifiers to screen Fantasia in theaters. This is an original 1940 RCA system used in one of those venues. It has four separate amplifiers, one for each sound channel. Touch the wrong leads and you’ll get zapped with 1,500 volts of DC juice. These beasts were locked in cages to safe-guard projectionists, but Weiss prefers to keep his triode amps under glass.

Amped Up Just your average collection of vintage RCA amplifiers. “It blows my mind that these machines still work,” Weiss says. “I hook them up to a Variac, slowly bring up the voltage, and they start to glow—it’s like magic.” A Variac is essential when working with old electronics; it prevents voltage spikes and surges that can fry your gear.

Rock Solid A couple of Weiss’ personally modified record players. The Technics SP-10 MKIII direct-drive turntable on the left rests on a vibration-smothering, 210-pound slate plinth (quarried and cut locally). The Gates CB-100 on the right is a 16-inch transcription turntable. In the 1940s, some live radio shows were recorded on 16-inch acetates, and stations around the country needed a turntable big enough to play those discs. On the lower shelf is one of Weiss’ dual-chassis phono preamps.

Sonic Truth Hardwood floors, bare windows, stone walls. That’s a lot of hard, reflective surfaces. No acoustic treatments? “The open wooden joists are excellent diffraction and diffusion devices,” Weiss says. “The open wood floor, three stories up, allows bass to dissipate without the reflections of small room boundaries. All the books, records, and furniture provide plenty of absorption. Two-foot thick stone walls also are excellent sonically. The room does not need ‘audiophile’ treatments.” Yeah, we knew that. Just asking.

Horn of Plenty The hefty black contraption attached to the back of that gorgeous walnut horn is the RCA MI-1428B, a magnificent piece of engineering that went out of production in 1939. It was the best field coil driver of its era. Some connoisseurs think it’s still the best. Weiss cornered the market on these beauties long ago; studying them is part of OMA’s R&D. Inside that silver thing that looks like a perforated coffee can is a tiny flame in a quartz cell heated to 1,000 degrees Celsius. This is mad scientist tech from the 1930s: a tweeter with zero mass, just the thing for transmitting high-frequency sound waves.

Big Audio Dynamite These mammoth speakers are the kind of horns that used to pump sound through cavernous movie palaces in the 1930s. Each weighs 250 pounds and has 18 cells. Part of RCA’s Shearer two-way commercial sound system, these behemoths can still project a movie soundtrack to the cheap seats at Radio City Music Hall with ease.

Cones of Loudness A formation of vintage horn speakers and other materials in Weiss’ workshop.

Press Play The console on the left is a vintage Ampex R2R tape machine (playback only—no recording heads). The three boxes that look like sci-fi B-movie props are 1950s-era Klangfilm cinema and studio amplifiers from Germany.

Cable System The exposed electrical system at the mill is called knob and tube. This early two-wire system (no ground) is likely the same technology Thomas Edison and Nikola Tesla used in their labs to conduct experiments. Why the old-school wiring? Weiss: “Because there isn’t any drywall to hide wires behind, and it’s incredibly cool looking.” Before you start nailing ceramic knobs into the ceiling, consult the National Electrical Code.

The Spirit of Radio “Flotsam and jetsam,” Weiss says of this assemblage. That’s a highly collectable RCA “On Air” studio sign. The vibrant red letters have faded over the decades.