After fixing the front of the box to obtain a baffle that is flush with the driver, I did some damping with SonoTec tiles (2'x4') on my grand piano to get rid of a reflection that bothered me. The first SPL measurement was performed at one meter distance as a reference to previously performed SPL measurements. We know by now that this is not perfect as this is too close to the 75" tall ribbons. Hence the 3 meter SPL measurement which gives a different inroom picture. The SPL measurements were confirmed at 1 kHz with a RSspl meter to within 1 dB. Amplifier voltage to the ribbon was in all cases 2.83 volt RMS as measured with a Tektronix digital scope.
For the 3 meter measurement I performed a run in SINE and in MLS mode to verify the correlation between the two types of measurement. Notice the difference in low response between the 1 meter and 3 meter measurement
