All plots below were taken from measurements of a prototype CXR-22 equalizing crossover with a crossover point at 150 Hz.
There are two sets of measurements. Both sets cover the same distances, only difference is the size and shape of the baffle. More info on these baffles will be published later. Pay attention to the dipole reinforcement "bump" behavior for both ribbon/baffle combinations. No attempt has been made in these measurements to equalize the dipole reinforcement peak as this involves a distance dependent correction.
Crossover settings in both cases were the same with exception of the ribbon baffle trim to accommodate the different size baffles.
Measurements were taken over an 85 millisecond interval with a 16k MLS sequence. The FFT was performed over 4096 points with an 1/12 octave smoothing. The magnitude scale on the plots is 6 dB/division. The magnitude between two horizontal grid lines is 3 dB. The top display shows phase behavior, bottom display shows the magnitude/frequency plot.
By the time you are reading this, changes have been made to the cavity resonance peak suppression. This peak is fairly wide on a RD75. It has also a flattened top in most cases. There is actually a change in shape measurable during the "break in" of the ribbon. New plots will be made and posted on a different page. The shape of the cavity resonance makes that a simple notch filter, passive nor active, is able to handle a perfect job.
The four plots below were taken on a different RD75 driver with a different baffle.
