The Philips HD series was a vast expansion of the previous product line to provide different feature sets at many different price points. The HD line looked visually similar despite large differences in performance and features.
The HD15 is a high-end ultrasound and the only HD series with the advanced single crystal probes. It remains popular though it’s been in production for nearly a decade and has no touchscreen like most in it’s class. The HD11xe was the best selling ultrasound machine Philips made, the highest selling in the midrange cardiovascular segment, but like all Philips machines it is a true shared service machine performing 4D and cardiac and has a dizzying selection of probes from the aforementioned 4D convex to TEE and intraoperative probes. The HD11xe is still an ultrasound machine that can do anything, and has the DNA of the Envisor HD and HDI 5000, which came before it. The HD 7xe is an economy version of the HD11xe with good imaging though no TEE or 4D probes. The HD7 and HD6 were nearly identical, though the HD6 was slightly newer and short lived.
The HD9 and HD3 were actually manufactured by Medison and used the SonoAce X8 and SonoAce R3/R5 as their hardware. Though they looked very different on the outside, internally the HD9 and X8 or HD3 and R3/R5 were so similar that they could use the same probes interchangeably.
The HD series currently continues in production only with the newly launched HD5 which borrows ClearVue styling but has hardware similar to the HD6 that preceded it. The HD5 is the most economical Philips unit in production and continues to be refined. Just like the ClearVue lineup the HD5 has a very limited amount of available probes. All of the HD series except the HD9 and HD3 which saw limited production are still available as used and refurbished units with a very good price to performance ratio.