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Message: <blockquote data-quote="Art Welter" data-source="post: 24324" data-attributes="member: 52">Re: Why Do TEF Systems read 3-5 dB high ?A 6.01 inch (152.7 millimeters) lift is  required at the back of an EAW AX cabinet to make the front perpendicular to the ground, a pallet and a 2 x 4 should “get er done” :^)I agree completely that good measurements are hard to get.The transfer function required to process semi-anechoic room results into full space results would require some serious software algorithms to yeild good results, though that is what EAW seems to do, reading their notes. Dave Gunness, with his background at EV prior to EAW, probably got that system as good as possible for that type of testing.It still seems to me that DSLs measurements, though internally consistant, are  +3 dB (or more) from other manufactures using half space sub measurements.Looking at the EAW AX112 Performance data , it says “see notes graphic data for details”, A couple of the notes:“5. Environment: Measurements time-widowed and processed to eliminate room effects, approximating an anechoic environment. Data processed as anechoic or fractional space, as noted.6. Measurement Distance: 7.46 m. Acoustic responses represent complex summation of the subsystems at 20 m. SPL is referenced to other distances using the Inverse Square Law.”The EAW AX112 sub spec sheet shows a 96 dB “whole space” sensitivity, which appears to be it’s sensitivity at about 70 Hz on the chart they provide. I would not expect you to try to measure it or any of your subs in whole space, you would need a ten story crane (or taller) to do it right without additional processing.Although the results of comparing a DSL sub to an EAW sub in half space would be interesting, the test methods that EAW uses makes the comparison a bit apples to oranges, as you have mentioned one can’t simply add 3 or 6 dB to equate a whole space to a half space measurement.Art Welter</blockquote>

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