The 400X, 5000, and 3190 are three motor (including dual speed hysteresis-synchronous capstan motor), fully transistorized professional tape recorders, designed to be used in the studio or out in the field, as their features make them capable of competing with the highest price console units, yet their size and weight permit them to be readily carried to a remote location for on-the-spot broadcast quality recordings. The self-contained power amplifiers in the 400X and 5000X drive the high-quality monitor speakers and provide 34 watts peak power per channel to the external speaker jacks. The Rheem 3190 series is the studio configuration of the 5000 series. The 3190 series features the tape transport and electronics used in the 5000 series, but without the portable case. The 3190 series may be console or rack mounted. The Rheem 3190 and 5000 series are available as quarter track stereo, half track mono, and full track mono units, designated by the suffix letter of the series number. “S” indicates quarter track; “H” indicates half track; and “F ” indicates full track heads. The 400X, 5000, and 3190 make use of the Crossfield bias system. This new system of supplying the bias to the tape permits the recording of high frequencies at tape speeds heretofore considered too slow for suitable reproduction. The bias is supplied by a separate head from the back of the tape and slightly before the tape passes the trailing edge of the record head gap. Consequently, the higher frequencies, which are more subject to partial erasure from the bias than the lower frequencies, are retained as they are recorded, yet sufficient bias is applied over the rest of the record head gap area to permit undistorted recording of lower frequencies and a low noise level. The results are impressive, as the units are capable of recording and reproducing from 30 cps to 17,000 cps, db 3 db at 33A ips, with a signal-to-noise ratio of 50 db.