The EMG 81 is a popular active humbucker guitar pickup manufactured by EMG, Inc.. It is usually considered a lead pickup for use in bridge position, paired with EMG 85 as a rhythm pickup in neck position (Zakk Wylde is famous for this configuration). It's not uncommon, however, to see a guitar with two EMG 81s in both bridge and neck positions (for instance, Kirk Hammett's EMG-KH21 pickup sets, which include 2 EMG 81 pickups for both neck and bridge positions).

The EMG 81 pickup is preferred as a lead pickup because of its high output and smooth control from having a rail magnet. Rail magnets tend to sound smoother through guitar bends because they have a constant "rail" that runs through the pickup, while typical ceramic magnets have poles at each string that lose signal strength as the string bends away from the ceramic pole. The EMG 81 can be recognized by its dark grey humbucker form-factor and a silver embossed EMG logo.

The EMG-81 was developed in 1979 along with the EMG 85, and was released to the market in 1981. Construction is similar to traditional U-shaped pickups, but there are no separate pole pieces; steel bars (rails) are used instead. Alnico magnets have been replaced with more powerful ceramic ones. While nominal output is the same as EMG 85, lower noise ratio gives more gain opportunity.

Christian Olde Wolbers (born 5 August 1972, Antwerp, Belgium) is the guitarist of the metal band Arkaea. He is the former bassist and guitarist of the industrial metal band Fear Factory, and is now in Beowülf.

Olde Wolbers was born in Belgium (though he has Dutch citizenship), and moved to the United States in 1993. He was asked to join Fear Factory in December 1993 as a bass player. He recorded five albums with them. The group disbanded in 2002 and when it reformed in 2003, Olde Wolbers had switched to guitar, replacing Dino Cazares. In 2009, Olde Wolbers and drummer Raymond Herrera parted ways with Fear Factory when vocalist Burton C. Bell chose to reform Fear Factory with Dino Cazares, bassist Byron Stroud, and drummer Gene Hoglan.

Olde Wolbers is currently working on musical project Arkaea with fellow ex-Fear Factory drummer Raymond Herrera and Jon Howard and Pat Kavanagh of the band Threat Signal. On 14 July 2009, Arkaea's debut album, Years in the Darkness was released.

Olde Wolbers is now in Beowülf, where he co-produced their 2011 album Jesus Freak.

Lester William Polsfuss (June 9, 1915 – August 13, 2009)—known as Les Paul—was an American jazz and country guitarist, songwriter and inventor. He was the inventor of the solid-body electric guitar which made the sound of rock and roll possible. He is credited with many recording innovations. Although he was not the first to use the technique, his early experiments with overdubbing (also known as sound on sound),delay effects such as tape delay, phasing effects and multitrack recording were among the first to attract widespread attention.

His innovative talents extended into his playing style, including licks, trills, chording sequences, fretting techniques and timing, which set him apart from his contemporaries and inspired many guitarists of the present day. He recorded with his wife Mary Ford in the 1950s, and they sold millions of records.

Among his many honors, Paul is one of a handful of artists with a permanent, stand-alone exhibit in the Rock and Roll Hall of Fame. He is prominently named by the music museum on its website as an "architect" and a "key inductee" along with Sam Phillips and Alan Freed.