The dbx 157 was a two-channel professional noise reduction system introduced in 1974 as part of the dbx 150 Series. Designed for serious recordists, small studios, and broadcasters, it offered simultaneous encode and decode operation, allowing users to monitor the decoded signal while recording. The dbx 157 employed dbx’s Type I broadband noise reduction system, based on the company’s patented linear 2:1 compression during recording and 1:2 expansion during playback. This process achieved approximately 30dB of hiss reduction and 10dB of added headroom, producing clean, transparent recordings free from the noise typical of analogue tape.
The dbx 157’s dual-channel design made it ideal for stereo applications and two-track mastering, while its internal architecture was engineered to match the performance of dbx’s larger studio systems. It featured true RMS detection circuitry for precise level control and accurate tracking between encode and decode stages. Because dbx’s companding system worked linearly across the full frequency range, the 157 avoided the breathing and pumping artefacts often associated with multi-band systems such as Dolby A. The result was a smooth, open sound with full dynamic integrity.
Each channel of the dbx 157 could be used for either encoding or decoding, or both simultaneously, making it exceptionally versatile for production and mixdown tasks. The unit required no calibration tones or alignment tapes, simplifying integration into any recording chain. Recordings encoded on the 157 could be decoded accurately on any other dbx Type I system, including the 150, 152, and 154, ensuring complete compatibility between project and professional studios.
Compact and ruggedly built, the dbx 157 could be used as a tabletop unit or mounted using the RM-150 rack kit, which accommodated two units side by side within an 89 mm rack space. Its simplicity, precision, and reliability made it one of the most effective stereo noise reduction systems available in the mid-1970s. The dbx 157 helped establish the 150 Series as the industry benchmark for broadband companding, offering professional sound quality in a compact, affordable form.
Features
- Two channels of broadband dbx Type I noise reduction
- Simultaneous encode and decode for monitoring while recording
- 30dB hiss reduction and 10dB increased headroom
- True RMS level detection for precise tracking
- Linear full-band companding with no breathing or pumping
- No calibration tones or alignment tapes required
- Compatible with all dbx 150 Series systems
- Compact tabletop or rack-mountable design
- Optional RM-150 rack kit for mounting two units in one 89 mm rack space
- High signal-to-noise ratio and transparent operation