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.
Check out my quest for bass page.