PAG/NAG Feedback Calculator

Calculate Potential Acoustic Gain (PAG) and Needed Acoustic Gain (NAG) to predict feedback margin.

Setup Diagram
TalkerMicrophoneSpeakerListenerD1 = 0.6D0 = 4D2 = 8Ds = 10D1 = Talker→Mic | D0 = Speaker→Mic | D2 = Speaker→Listener | Ds = Talker→Listener
Distances

Closer = better gain

Further = better gain

The gap to fill with amplification

Farthest listener from speaker

Results

PAG

-20.5

dB

NAG

1.9

dB

Margin

-22.5

dB

FEEDBACK RISK

Insufficient gain before feedback. Adjust setup.

Suggestions to Improve Margin
  • • Move microphone closer to the talker (reduce D1)
  • • Increase distance between loudspeaker and microphone (increase D0)
  • • Use directional microphones and/or loudspeakers
  • • Consider acoustic treatment to reduce room reflections
Formulas

PAG = 20log(D1) - 20log(D2) + 20log(Ds) - 20log(D0) - 10log(NOM) - 6dB

NAG = 20log(Ds) - 20log(D2)

Margin = PAG - NAG (need ≥ 6dB)