The SPL measurements shown in the next graph were made at a distance of 0.5m on the baffle, which is 1m x 1.2m, with the driver centered on the baffle. This helps to lower the frequency at which the measurement is still valid and excludes any diffraction effects when windowed properly. They are all very close from 2k-10khz. Above 10khz the grouping of the three older drivers is also close. The new one is a bit higher with less variation. Considering the time difference in the purchases, I feel that this is very good consistency.
The next graph has three curves for one of the newer drivers, all taken on the quasi-IEC baffle. The on-axis, 15 degree and windowed measurements show that even though the on-axis response is ragged, the power response (approximated by the windowed average) is not that bad. The variation is about +/- 2db above about 12khz.
I can't come to any conclusions as to why the response is as it is above the 12k point. I guess that it has to do with the dome material and doping compound. The internal damping of the material/doping must be very frequency dependent and changes dramatically. The shape has something to do with this as well, but the shape is very similar to many other drivers.
| MDT-20 | MDT-30 |
