Brian, on my side, when using the same curve, the R1900 produces lighter result than the 3800. The LAB L values given previously came from the 3800. I have just printed the same ramp with the R1900 on Epson HPN, and the better Dmax is now at 16.02. But 14.92 on the 3800.
Paul, you will find the files here . There is 2 shades, one 100% Eboni v1.1, the other diluted with c6b, 30% Eboni v1.1. All targets printed at 2880dpi, unidirectional. The separation parameters for the linear target are in the screenshot.