Historical clue formulations

• Electronically produced echo effect — 2025-07-01
• Electronic echo effect — 2024-06-03
• Echo effect — 2023-10-18
• Effect created by a guitar pedal, informally — 2021-08-11
• Recording studio effect — 2017-10-22
• Echo effect — 2017-01-08
• Addition to the mix — 2015-03-13
• Label on an amplifier knob — 2008-11-21
• Reflected sound effect — 2004-06-16
• Recording effect — 2001-02-18
• Studio effect — 1998-02-04