The DL4 by Line 6, introduced in 1999, is one of the first digital modeling effects unit

Effects unit

Effects units are electronic devices that alter how a musical instrument or other audio source sounds. Some effects subtly "color" a sound, while others transform it dramatically. Effects are used during live performances or in the studio, typically with electric guitar, keyboard and bass...

s. The DL4 features models of 16 vintage delay effects, including the Echoplex

Echoplex

The Echoplex is a tape delay effect, first made in 1959. Designed by Mike Battle, the Echoplex set a standard for the effect in the 1960s and was used by some of the most notable guitar players of the era; original Echoplexes are highly sought after....

, Roland Corporation

Roland Corporation

is a Japanese manufacturer of electronic musical instruments, electronic equipment and software. It was founded by Ikutaro Kakehashi in Osaka on April 18, 1972, with ¥33 million in capital. In 2005 Roland's headquarters relocated to Hamamatsu in Shizuoka Prefecture. Today it has factories in Japan,...

's Space Echo, and the Electro-Harmonix

Electro-Harmonix

Electro-Harmonix is a New York-based company that makes high-end electronic audio processors. The company was founded by Mike Matthews in 1968. They are most famous for a series of popular guitar effects pedals introduced in the 1970s and 1990s....

 Deluxe Memory Man. It is also used for looping

Music loop

In electroacoustic music, a loop is a repeating section of sound material. Short sections of material can be repeated to create ostinato patterns...

. According to a May/June 2000 review in Canadian Musician

Canadian Musician

Canadian Musician is a Canadian magazine that is published bi-monthly by Norris-Whitney Communications Inc. Published since 1979, the magazine's primary area of interest is to profile Canadian musicians and musical events. The magazine also writes articles on the Canadian music business and...

, it "delivers a cavalcade of features for a reasonable price."