The 500-series format is a standardized format for a modular

signal processor Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as sound, images, potential fields, seismic signals, altimetry processing, and scientific measurements. Signal ...

system consisting of a combination of 500-series modules installed within a 500-series chassis (or rack), with the chassis providing power and audio connections for the individual modules. Originally invented by

Automated Processes, Inc. Automated Processes Inc. (API or API Audio) is an American company that designs, manufactures, and markets mixing consoles and Audio signal processing, signal processors, including modular signal processor units in the 500-series format standa ...

co-founder Saul Walker, today numerous companies manufacture 500-series format products. The modular nature of the 500-series format allows individual modules to be combined to create a customized

signal processing Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as audio signal processing, sound, image processing, images, Scalar potential, potential fields, Seismic tomograph ...

chain, with individual modules added or changed as budget allows. Many 500-series chassis also offer portability, allowing a recording engineer to bring their desired signal processing chain to any recording session.

History

In 1967, Lou Lindauer and Saul Walker designed a

mixing console A mixing console or mixing desk is an electronic device for Audio mixing (recorded music), mixing audio signals, used in sound recording and reproduction and sound reinforcement systems. Inputs to the console include microphones, signals fro ...

for Apostolic Recording Studio, the first 12-track recording studio in New York City. The console's modular design, invented by Walker, became the 500-series format, and Walker and Lindauer co-founded

(API) in 1969. API's 500-series modules include the 512C

preamplifier A preamplifier, also known as a preamp, is an electronic amplifier that converts a weak electrical signal into an output signal strong enough to be noise-tolerant and strong enough for further processing, or for sending to a power amplifier a ...

, the 525

compressor A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Many compressors can be staged, that is, the gas is compressed several times in steps o ...

, the 527 compressor, the 550A and 550B semi-parametric equalizers, and the 560 graphic equalizer. In the mid-1970s, some recording engineers began removing individual processor modules from API mixing consoles and installing them into homemade mounting systems. In 1978, Datatronix licensed the rights to API from the owners and manufactured a 10-slot 500-series chassis. In 1985, the assets of API were purchased by Paul Wolff. In response to increasing demand, Wolff introduced the API Lunchbox, a portable chassis for housing 500-series modules in 2-slot, 6-slot, and 10-slot configurations. Later, API would establish ownership of the Lunchbox trademark. Popularity in the 500-series format surged in the mid-2000s, and by 2020, there were over five hundred different 500-series modules on the market from API and numerous third-party manufacturers, including Neve,

Solid State Logic Solid State Logic Ltd. (SSL) is a British company based in Begbroke, Oxfordshire, England that designs and markets audio mixing consoles, Audio signal processing, signal processors, and other audio technologies for the post-production, video p ...

, Aphex,

dbx dbx or DBX may refer to: * dbx (debugger), a Unix source-level debugger * dbx (company), a professional audio recording equipment company ** dbx (noise reduction), a noise reduction system invented by dbx, Inc. * .dbx, the file extension for Micros ...

, and others.

VPR Alliance

In 2006 API established the VPR Alliance, which established 500-series specification standards to ensure compatibility with API 500-series rack systems. VPR Alliance standards dictate voltage at +/- 16 volts, with +48 volts for phantom power, with maximum current draw of 130, 130 and 5 mA respectively per slot. Each module has three input and output pins, for +4db, -2dB and negative balanced signals. The physical dimensions are 3U vertically (5.25") and multiples of 1.5" wide, with 15-pin edge-connector pin configuration of 500-series modules.

References

External links

*
Saul Walker Interview
at NAMM Oral History Collection {{Music industry Sound production technology Effects units Audio effects Mechanical standards Electronics standards