Before 2, Trax’s clientele is young (minimum age for admission is 18, and no liquor is served) and predominantly gay. Ingram’s after-hours innovation was an instant sensation. Last spring, Bruce Ingram, owner of Trax, a new disco in the Gaslamp Quarter, introduced a social attraction common to most major cities but new to San Diego-a four-hour dance starting at 2 a.m.