RBH transducer measurements 10/17/97



The set up was 4 RBH transducers sandwiched between the couch and the floor powered by a 150W amp with the crossover set at 180Hz. A function generator was the signal source and was set to: .5 Vpp sine wave output. The noise floor of the room was around 50 dB SPL C and the noise floor of the chest test cavity was 58 dB accounting for the sound of the beating heart with in it. Two of the Radio Shack 33-2050 sound level meters were used. One was placed on the center cushion right where a persons butt would typically be and the other SPL meter was held against the chest test carcass by my faithful assistant "Beaker".

Here a two plots using a flat EQ response. The "air" SPL measurement was taken on a couch seat and the "chest" SPL measurement was, well, strapped to the test carcass which was seated on the couch.






Same as above plot plus the data from a prototype run of air SPL measurements with the crossover set at 80Hz.






EQ table


curve 25Hz 31Hz 40Hz 50Hz 62Hz 80Hz gain dB
flat 0 0 0 0 0 0 0
EQ1 +12 +8 -12 -12 +6 0 0
EQ2 +12 +8 -12 -12 +6 0 +12
EQ3 +12 +8 -24 -24 +6 0 +12


Plots comparing different EQ curves on the air and chest measuring points.






Plots comparing different EQ curves on the air and chest measuring points that have been normalized for comparison purposes at the reference point of 45Hz and 90dB.




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