Introduced in late 1989, several months after the DFX9, the DFX91 appeared to have been marketed as DOD's "pro" level compact digital delay pedal (much in the same way the Boss DD-5 was marketed relative to the DD-3 upon its debut). The DFX91's basic circuit was similar to the DFX9, but with "sample" and "trigger" settings in addition to infinite repeat. While the sampling ability of the DFX91 was limited by its maximum 1 second of delay time, it was more than the 0.8 seconds offered by the Boss DSD-2/DSD-3, which were released a few years earlier. The DFX91 was effectively discontinued with the debut of the DFX94 in late 1993, although it was offered alongside the DFX94 through at least Fall 1994.
 
Controls:
Two LEDs (left LED indicates delay effect is on; when the Range/Mode switch is set to Sample, the right LED is lit after a sampled phrase is recorded)
 
Level (no delay when counterclockwise, 50% wet/dry mix when fully clockwise)
 
Repeat (1-20 repeats)
 
Delay 6-position Range/Mode rotary switch:
13.8-62.5 ms of delay
55.5-250 ms
222-1000 ms