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with another dip of 3db or so at 120-150db or so.
Ian has explained this dip before.
"In reference to the little dip and rise at 150 Hz in the M80 compared to the M60; it is just the microphone positioning being up right under the tweeter and only 2 meters back in the anechoic chamber giving it an increased angle of attack on the very tall M80s."
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We can see that beginning at 60hz and down the M80’s are already off by 3db
This too has been explained.
"The chamber is accurate to 85 Hz and then there is a correction applied below that. For heightened accuracy of measurements below 85 Hz we measure out on our pole in mid air. The pole puts the product and microphone up about 20 feet in the air. The sub graphs above are from the pole. You can see in the NRC graph above of the M60 the bass rolls off quickly below 37 Hz and this trend lines up with the pole measurements of the bass response of an M60, hence the 37 Hz spec."
Peak SPL calculator
Rick
"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud
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