Question: When was Bob Stroger's musical instrument invented?

full_context: Document 1: Ned Steinberger: Ned Steinberger (b. Princeton, New Jersey, 1948) is an American creator of innovative musical instruments. He is most notable for his design of guitars and basses without a traditional headstock, which are called Steinberger instruments. He also has a line of electric basses and string instruments through his company called NS Design and was also the designer of the first ever Spector bass, the NS. In addition, Ned and Emmett Chapman, creator of the Chapman Stick, collaborated on the creation of the NS Stick, a guitar/bass "multi-mode" instrument sold by Stick Enterprises.
Document 2: Mandolin: Numerous modern mandolin makers build instruments that largely replicate the Gibson F-5 Artist models built in the early 1920s under the supervision of Gibson acoustician Lloyd Loar. Original Loar-signed instruments are sought after and extremely valuable. Other makers from the Loar period and earlier include Lyon and Healy, Vega and Larson Brothers. Some notable modern American carved mandolin manufacturers include, in addition to Kay, Gibson, Weber, Monteleone and Collings. Mandolins from other countries include The Loar (China), Santa, Rosa (China), Michael Kelly (Korea), Eastman (China), Kentucky (China), Heiden (Canada), Gilchrist (Australia) and Morgan Monroe (China).
Document 3: Mandolin: Another family of bowlback mandolins came from Milan and Lombardy. These mandolins are closer to the mandolino or mandore than other modern mandolins. They are shorter and wider than the standard Neapolitan mandolin, with a shallow back. The instruments have 6 strings, 3 wire treble-strings and 3 gut or wire-wrapped-silk bass-strings. The strings ran between the tuning pegs and a bridge that was glued to the soundboard, as a guitar's. The Lombardic mandolins were tuned g b e' a' d" g". A developer of the Milanese stye was Antonio Monzino (Milan) and his family who made them for 6 generations.
Document 4: Born Under a Bad Sign (song): "Born Under a Bad Sign" is a blues song recorded by American blues singer and guitarist Albert King in 1967. Called "a timeless staple of the blues", the song also had strong crossover appeal to the rock audience with its bass and guitar harmony line and topical astrology reference. "Born Under a Bad Sign" became an R&B chart hit for King and numerous blues and other musicians have made it perhaps the most recorded Albert King song.
Document 5: Bob Stroger: Bob Stroger (born December 27, 1930) is an American electric blues bass guitarist, singer and songwriter. He has worked with many blues musicians, including Eddie King, Otis Rush, Jimmy Rogers, Eddie Taylor, Eddy Clearwater, Sunnyland Slim, Louisiana Red, Buster Benton, Homesick James, Mississippi Heat, Snooky Pryor, Odie Payne, Fred Below, Willie "Big Eyes" Smith, and Billy Davenport.
Document 6: Bass guitar: In the 1930s, musician and inventor Paul Tutmarc from Seattle, Washington, who was manufacturing lap steel guitars, developed the first electric string bass in its modern form, a fretted instrument designed to be played horizontally. The 1935 sales catalog for Tutmarc's electronic musical instrument company, Audiovox, featured his ``Model 736 Bass Fiddle '', a four - stringed, solid - bodied, fretted electric bass instrument with a 30 ⁄ - inch (775 - millimetre) scale length. The adoption of a guitar's body shape made the instrument easier to hold and transport than any of the existing stringed bass instruments. The addition of frets enabled bassists to play in tune more easily than on fretless acoustic or electric upright basses. Around 100 of these instruments were made during this period.
Document 7: Höfner 500/1: The Höfner 500/1 violin bass (nicknamed the "Beatle bass" or "Cavern bass") is a hollow-bodied bass guitar manufactured by Höfner under several varieties. It was introduced in the mid-1950s and gained celebrity status during the 1960s as one of the primary basses used by Paul McCartney of The Beatles.
Document 8: Solid body: The origins of the solid body electric guitar are confusing. The first commercially available solid body electric Spanish guitar was produced by the Rickenbacker company in 1931. Les Paul, a guitarist, is often erroneously credited with inventing the first solid body, but Fender is often incorrectly credited as the first to commercially market a solid body electric guitar, which itself was based on a design by Merle Travis. Also it is reported that around the same time (1940) a solid body was created by Jamaican musician and inventor, Hedley Jones. In the 1940s, Les Paul created a guitar called the ``Log, ''which came`` from the 4'' by 4 ''solid block of pine which the guitarist had inserted between the sawed halves of the body that he'd just dismembered. He then carefully re-joined the neck to the pine log, using some metal brackets.'' He then put some pickups that he designed on it. He soon went to companies asking if they would buy his guitar. They turned him down. However, after the Fender Telecaster electric guitar became popular, the Gibson company contacted him and had him endorse a model named after him, The Les Paul guitar. It came out in 1952.
Document 9: Lefty Bates: Lefty Bates (March 9, 1920 – April 7, 2007) was an American Chicago blues guitarist. He led the Lefty Bates Combo and worked with the El Dorados, the Flamingos, Jimmy Reed, John Lee Hooker, Buddy Guy, Etta James, the Aristo-Kats, the Hi-De-Ho Boys, the Moroccos, and the Impressions. A regular on the Chicago blues scene, his major work was as a session musician on numerous recordings in the 1950s and 1960s.
Document 10: Mandolin: Mandolin has also been used in blues music, most notably by Ry Cooder, who performed outstanding covers on his very first recordings, Yank Rachell, Johnny "Man" Young, Carl Martin, and Gerry Hundt. Howard Armstrong, who is famous for blues violin, got his start with his father's mandolin and played in string bands similar to the other Tennessee string bands he came into contact with, with band makeup including "mandolins and fiddles and guitars and banjos. And once in a while they would ease a little ukulele in there and a bass fiddle." Other blues players from the era's string bands include Willie Black (Whistler And His Jug Band), Dink Brister, Jim Hill, Charles Johnson, Coley Jones (Dallas String Band), Bobby Leecan (Need More Band), Alfred Martin, Charlie McCoy (1909-1950), Al Miller, Matthew Prater, and Herb Quinn.
Document 11: Howlin' Wolf: Chester Arthur Burnett (June 10, 1910 – January 10, 1976), known as Howlin' Wolf, was a Chicago blues singer, guitarist, and harmonica player, originally from Mississippi. With a booming voice and imposing physical presence, he is one of the best-known Chicago blues artists. The musician and critic Cub Koda noted, "no one could match Howlin' Wolf for the singular ability to rock the house down to the foundation while simultaneously scaring its patrons out of its wits." Producer Sam Phillips recalled, "When I heard Howlin' Wolf, I said, 'This is for me. This is where the soul of man never dies. Several of his songs, including "Smokestack Lightnin'", "Killing Floor" and "Spoonful", have become blues and blues rock standards. In 2011, "Rolling Stone" magazine ranked him number 54 on its list of the "100 Greatest Artists of All Time".
Document 12: Mandolin: The instrument was primarily used in an ensemble setting well into the 1930s, and although the fad died out at the beginning of the 1930s, the instruments that were developed for the orchestra found a new home in bluegrass. The famous Lloyd Loar Master Model from Gibson (1923) was designed to boost the flagging interest in mandolin ensembles, with little success. However, The "Loar" became the defining instrument of bluegrass music when Bill Monroe purchased F-5 S/N 73987 in a Florida barbershop in 1943 and popularized it as his main instrument.
Document 13: Robert Johnson: Robert Leroy Johnson (May 8, 1911 -- August 16, 1938) was an American blues singer - songwriter and musician. His landmark recordings in 1936 and 1937 display a combination of singing, guitar skills, and songwriting talent that has influenced later generations of musicians. Johnson's poorly documented life and death at age 27 have given rise to much legend. One Faustian myth says that he sold his soul to the devil at a local crossroads of Mississippi highways to achieve success. As an itinerant performer who played mostly on street corners, in juke joints, and at Saturday night dances, Johnson had little commercial success or public recognition in his lifetime.
Document 14: Muddy Waters: McKinley Morganfield (April 4, 1913 -- April 30, 1983), known professionally as Muddy Waters, was an American blues musician who is often cited as the ``father of modern Chicago blues ''.
Document 15: Music Man Bongo: The Bongo is a model of bass guitar manufactured by Music Man, a division of Ernie Ball. It was first introduced at the NAMM Show on March 21, 2003. Ernie Ball president Sterling Ball designed the instrument in conjunction with the Music Man Research and Development department and BMW's Designworks team. It is equipped with an 18-volt 4-band preamp (except on the single-pickup model, which has a 3-band preamp; single-pickup models with piezo bridges have a 4-band preamp) designed by Dudley Gimpel with help from Cliff Hugo and other Music Man artists. It also sports a sleek, carved basswood body with high-gloss polyester finish and a satin-finish painted 34" scale maple neck with rosewood fingerboard (pau ferro on lined or unlined fretless, ebony on both fretted and fretless "stealth" basses) featuring 24 high-profile wide frets and crescent moon-shaped position inlays. These basses are generally known for their dual humbucking pickup configuration, as they are the first twin humbucker-equipped models released by Music Man since the introduction of their Sabre and Cutlass bass guitars in the late 1970s.
ground_truth: the 1930s
sub_queries: Bob Stroger >> instrument Answer: bass guitar
when was the first electric bass guitar made Answer: the 1930s