Commercial Fixed Wing
Air Traffic Control Fully Certified
Communication Breakdown; Distraction; Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance
Airspace Structure; Human Factors
Aircraft X in a string for the downwind landing north. I thought I issued 9;000 ft. because the MVA (Minimum Vectoring Altitude) is 8;500 ft. I saw Aircraft X at 8;300 ft. and told them to climb immediately and bungled up the phraseology while attempting a safety alert (which did not go off).  After reviewing the replay; I actually had issued Aircraft X 8;000 ft. I can only assume 8;000 ft. was on my mind because when I base aircraft I give them a heading of 180 and 8;000 ft. I issued the incorrect altitude and attempted to catch it before it was a loss with terrain; but did not. Although multiple things were going on; I should have been more vigilant in my hear-back.
A TRACON Controller reported they mistakenly assigned an aircraft an altitude below the Minimum Vectoring Altitude.