Barely expanding on Beck's "two turntables and a microphone" formula, improvisational music mastermind Howard Stelzer doesn't make songs, he forges moments of noise, hiss and silence with cassette players, dirty old tapes, a mic and a mixer. Sometimes, the bursts are akin to firecrackers in a dentist's office. Other times, he builds up to little more than silent pauses. But even the slow-rising swells of found sound feel as brazenly loud and rude as his sudden, in-the-red roars.

Whether in a concert setting or across several albums on his Intransitive label (including Stone Blind, and collaborations with fellow hiss-ers Brendan Murray and Jason Talbot), Stelzer, 30, makes his tape decks rock with a sound closer to rhythmic "hits" than something chartable by musical notation. "Tones happen whether I want them to or not," he says of the brutal squeal and smack of his decks. "But I'm more interested in sustained clusters of ephemeral sounds, or else isolated snips of the shitty sounds that only low tape technology can make."

With a primitive rig of four cassette Walkmans, one CD player fed through a Behringer mixer and one microphone hooked up to a distortion pedal, his sounds are generated by speeding up and slowing down cassettes with his fingers. Because the tops of his tape decks are exposed, he can directly access the reels, with his lone pedal used for gain, abrupt stop-and-starts and hastened muting and unmuting.

"My music is not composed of recorded sounds being played back," he tries to explain, "but of sonic gestures that spring from a player interacting with tangible materials, guided by whatever feedback I get from the audience."

A raging punk club might find itself awash in harsh punctuated pulses. A calm concert hall might find Stelzer set adrift on memory's bliss.

"I keep a perceptible relationship between my physical gestures of interacting with the machines and the sounds that result from those gestures. So my performances tend to be physical. Not in an overacting, cheesy rock-out sort of way. At least, I sure as hell hope not. I like for people to know that the sounds are coming out of one person, as opposed to being emitted by a bodiless piece of plastic."

After having spent his youth in Boca Raton, splicing tapes of "metal junk" he found in dad's garage, Stelzer stumbled onto "noise" through Negativland ("big big nerd, yes sir") and catalogs from eclectic Massachusetts imprint RRRecords. "When I got my first order, I was changed forever." Stelzer moved to Boston, where he lives, works and runs Intransitive.

He learned to make collages from his collages to bury the source material. To him, the sound of manipulation makes the most difference. He doesn't say what his sounds are or were.

"I am more concerned with an instrumental "playing' of the tapes than with reorganizing the sounds that I've recorded. I don't care what the sounds on my tapes are; they could be anything, really."

Like his work with turntablist Talbot, Stelzer's "songs" are short and fast-paced, with a wide dynamic range, tense near-silences and blurts of noise and midrange mud. This is not computer music, or laptop pop. This is the analog glug, belch, whirr and yech of cassette tapes at their often-grimey, mostly crackled best.

He doesn't romanticize the souls of found sound or the ghosts within the machinery. "No. My tape decks misbehave because I tax their motors and don't store them properly. Souls? No, it's just dirt stuck in the batteries. As for me being hostile to computer music, I just love the sound of tape, and the visceral quality of manipulating cassettes with my hands. I like for my entire body to be involved in music making."

Thu., Jan. 6, 9 p.m., $8, with Birchville Cat Motel, Fursaxa and Donna Parker, The Khyber, 56 S. Second St., 215-238-5888.