DigiTech HARDWIRE HT-6 Owner's Manual page 14

Selecting A Tuner Reference
The HT-6 Tuner has multiple tuning references to select from:
• A=436 - 445 (including A=440 standard tuning)
• A=A♭
• A=G
• A=G♭
• A=F
• A=E
*Half step to 5 half steps below standard A440.
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