Providing Foldback with Out-of-Phase Loudspeakers

Jones ES. Providing Foldback with Out-of-Phase Loudspeakers. J Audio Eng Soc. 1971;19(4):306-309. Available from: https://aes.org/publications/elibrary-page/?id=2179

@article{Jones1971_2179,
  author = {Jones, Edward S.},
  title = {{Providing Foldback with Out-of-Phase Loudspeakers}},
  journal = {Journal of the Audio Engineering Society},
  volume = {19},
  number = {4},
  pages = {306--309},
  year = {1971},
  month = apr,
  publisher = {Audio Engineering Society},
  url = {https://aes.org/publications/elibrary-page/?id=2179}
}

TY  - JOUR
TI  - Providing Foldback with Out-of-Phase Loudspeakers
AU  - Jones, Edward S.
T2  - Journal of the Audio Engineering Society
J2  - J. Audio Eng. Soc.
VL  - 19
IS  - 4
SP  - 306
EP  - 309
PY  - 1971
DA  - 1971/04/06
UR  - https://aes.org/publications/elibrary-page/?id=2179
PB  - Audio Engineering Society
LA  - en
AB  - Providing adequate foldback sound level to performers on the stage or to dignitaries seated behind the podium has been a long-standing problem for sound reinforcement engineers. The level required is generally well above that which can be provided and still avoid sustained feedback or singing. This problem can be overcome in many cases by connecting loudspeakers in an out-of-phase circuit configuration and placing the microphone in the resulting area of cancellation. Actual field tests providing foldback to dignitaries behind the podium resulted in as much as 15 dB additional gain before feedback. Anechoic chamber and field test results on variations of this method are described.
ER  -