The Wolfbox is the name for the original passive

DI unit A DI unit (direct input or direct inject) is an electronic device typically used in recording studios and in sound reinforcement systems to connect a high-output impedance, line level, unbalanced output signal to a low-impedance, microphone level ...

, direct box, or DI as invented in the late 1950s by Dr. Edward Wolfrum, PhD, alumnus engineer of

Motown Motown Records is an American record label owned by the Universal Music Group. It was founded by Berry Gordy Jr. as Tamla Records on June 7, 1958, and incorporated as Motown Record Corporation on April 14, 1960. Its name, a portmanteau of ''moto ...

Golden World Records Golden World Records was a record label owned by Eddie Wingate and Joanne Bratton (née Jackson, former wife of boxing champion Johnny Bratton). The recording studio was located in Detroit, Michigan, United States. The studio's national hits incl ...

, Terra-Shirma Studios, Metro-Audio Capstan Roller Remote recording, and

United Sound Systems United Sound Systems is a recording studio and locally designated historic district in Detroit, Michigan, United States. Many popular music artists over the last seventy years have recorded at the facility, including blues musicians like John Lee ...

Detroit, Michigan Detroit ( , ; , ) is the largest city in the U.S. state of Michigan. It is also the largest U.S. city on the United States–Canada border, and the seat of government of Wayne County. The City of Detroit had a population of 639,111 at ...

. Used by

James Jamerson James Lee Jamerson (January 29, 1936 – August 2, 1983) was an American bass player. He was the uncredited bassist on most of the Motown Records hits in the 1960s and early 1970s (Motown did not list session musician credits on their releases u ...

Dennis Coffey Dennis James Coffey (born November 11, 1940) is an American guitarist. He was a studio musician for many soul and R&B recordings, and is well known for his 1971 Top 10 hit single " Scorpio". Biography Coffey learned to play guitar at the ag ...

, Bob Babbit and other

The Funk Brothers The Funk Brothers were a group of Detroit-based session musicians who performed the backing to most Motown recordings from 1959 until the company moved to Los Angeles in 1972. Its members are considered among the most successful groups of stud ...

, the Wolfbox was a key component in the 1960s and 1970s sound of recorded music in the Motown/Detroit scene.

Origin

According to Wolfrum, the idea for the creation of the device originally came to him out of necessity, from "…Recording bands back then arly 1960sand the fact that I simply couldn't afford microphones." It was at Detroit's WEXL in 1962 that 16-year-old staff engineer Wolfrum incorporated his newly created passive direct interface box – later known at the "Wolfbox" – as an interface from the high-impedance output of church PA systems to the microphone input of broadcast audio mixers.

Recent versions

In 2013, a limited-edition run of 25 new Wolfboxes were designed, plotted, supervised & signed by Dr. Wolfrum, in a non-exclusive (unlicensed) agreement with Acme Audio Mfg. Company. Using NOS components and original A-11J and A-12J triad transformers sourced from vintage gear, these new versions found their way to such places as Nashville's Blackbird Studios, London's

Abbey Road ''Abbey Road'' is the eleventh studio album by the English rock band the Beatles. It is the last album the group started recording, although ''Let It Be'' was the last album completed before the band's break-up in April 1970. It was mostly re ...

, and to

Blue Note Records Blue Note Records is an American jazz record label owned by Universal Music Group and operated under Capitol Music Group. Established in 1939 by Alfred Lion and Max Margulis, it derived its name from the blue notes of jazz and the blues. Or ...

President and bassist Don Was. After the 25-unit production, Dr. Wolfrum ended his Acme collaboration and released his schematic of the Wolfbox in 2014 for free public non-commercial use. To date Acme Audio Mfg. Co. produces The Motown DI which uses original OEM Triad transformers.

Molybdenum and limited resources

The original Wolfboxes relied on vintage A-11J and A-12J Triad transformers (manufactured up to 1974) whose metal structure (i.e. Molybdenum composition) became regulated due to mining and manufacturing toxicity by OSHA and EPA restrictions.NIOSH Chemical Hazards
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References

External links

- Audio Graphic Services
Ed Wolfrum interview on United Sound
- TQM Recording Co.
Wolfbox Schematic
- PDF, Audio Graphic Services
Video interview with Dr. Edward Wolfrum
- Detroit Free Press video interview, Brian Kaufman and Brian McCollum
Soul-Source Article
- "Ed Wolfrum - Detroit Sound" 2012 excerpt by Rob Moss from forthcoming book
WDET Interview
- "Motown Legends Dr. Ed Wolfrum and Paul Riser" The Craig Fahle Show, WDET-FM
Molybdenum Toxicity PDF
- "What You Should Know About Molybdenum" PDF, Texas Dept. of State Health Services {{DEFAULTSORT:Wolfbox Sound recording technology Audio engineering Audio mixing