Where do you go if you want to get your hands on the one available tape of Langston Hughes reading his poetry? Or if you are a poet seeking advice on where to hold a reading? Or if you want to listen to the work of Ntazake Shange, instead of reading it?

Black Box.

Black Box started in Washington in 1973, is the first literary magazine on cassette tape. It is also one of several programs undertaken by the Watershed Foundation, a non-profit organization founded to develop a larger audience for contemporary poetry.

The tapes, of which there have been 12 issues, range in length from two to three hours. They are produced at the Watershed Foundation's Capitol Hill office and feature local and nationally known poets reading their own work.

The name, says founder and editorial director Alan Austin, is an engineer's term for a handmade device that makes two independent systems function together. (One example is a mixer that can produce a single recording from two seperate tracks.)

In this case, explains Austin, the two separate systems are the author and the audience.

Austin conceived the idea for Black Box in 1971. After spending the 1960s involved in the civil rights and antiwar movements and working as poetry and science editor for Motive, a Nashville based magazine, he wanted to start his won publication. When he moved to Washington, Austin began to listen to black poets read their works aloud.

"When I was at Motive, a lot of black poetry came across my desk - and I have to confess now that I didn't like reading it. My ear had been schooled in the white Anglo-Saxon literary tradition. It wasn't until I heard the poems performed that it all came together for me.

"I realized that the poetry I care about needed to be heard," explained Austin.

The material issued by Black Box is meant to provide an overview of what's happening in American poetry - the whole range of it."

At first, said Austin, he had a rule of devoting at least one hour per issue to black poetry, which, with a strong oral tradition was naturally suited to tape presentation. Now, he has become more flexible.

One upcoming issue will deal exclusively with sound-text poetry. In this technique, documents or literary works are read aloud and altered electronically - for example, played back at varying speeds or backwards - and thus transformed into a new work.

Other Black Box issues have included songs, chants, radio plays and collaborations between poets and musicians.

Some of the tapes include such well-known poets as Allen Ginsberg, Pablo Neruda, robert Bly and Robert Creeley. Other tapes, such as "The Washington Sound," were the product of 16 months of taping in 1975 and 1976, conducted with a grant from the D.C. Commission on the Arts and Humanities. Black Box opened its recording studio to all working poets in the D.C. area, and recorded 307 writers.

The final, three-hour issue presents the work of 37 local authors, and includes excerpts from readings at the "Ascension Series" for young black poets.

Ann Darr, a poet whose work is included in the issue, explains the attraction of recording her work on tape.

"I hear my own poems as they come through my ears, and I like them to be available to others that way, too," she said. She added that Black Box also expands her audience by making poetry available to schools that cannot afford to sponsor readings, and to libraries that normally stock only the graybeard poets.

Darr is a subscriber to Black Box, too. "I like to hear poems in the poet's own voice. I want to get the feeling and the melody out of the voice - there's so much melody there," she said.

BLack Box now has about 300 subscribers for its four-times-a-year magazine on tape. Of these, about one-third are libraries and the rest are individuals. In addition, the issues are available independently, and Austin says most have sold more than 1,000 copies.

At the rate of $16.75 a year for individuals and $34 a year for institutions, subscription fees pay less than half the production costs of the cassette magazine, which are expected to total about $27,000 in 1978.

The rest of the funds, Austin said, come from contributions and grants. Black Box had to suspend publication entirely for a year between 1973 and 1974 when sufficient funds could not be raised. Since its start, Black Box has received grants from the National Endowment for the Arts, the D.C. Commission on the Arts and Humanities, and the Council of Literary Magazines.

For two years, the Folger Shakespeare Library donated space to Black Box and its umbrella organization, the Watershed Foundation, at 305 East Capitol St. Planned expansion by the Folger forced Black Box to find a new office, and the organization is moving downtown this week to the Atlantic Building, at 9th and F Streets NW.

Austin said he hopes that the additional studio space in the Atlantic Building will enable the Watershed Foundation to upgrade its recording facilities and thus undertake new projects.

Another program sponsored by Watershed Foundation is the "North American Poetry Network," which offers radio stations throughout the country poetry readings, radio plays, and discussions among poets on the nature of their craft. The foundation also serves as an information clearing-house and distribution center for cassettes of individual poets and poetry readings, and provides consulting services for poets who wish to record their work or find opportunities for public readings.