Difference between Roland HP 601 and 603 digital piano

Question

Does anyone know the difference between Roland HP 601 and 603/605 digital piano? The HP-601 came out later than the 603 and 605 models and it is a bit cheaper. Cannot find any online review of the 601. Looking at the specs they are nearly identical to the 603 and the 605 except the sound system (which matters nothing if you are only using headphones), plus one more point: the sound engine is described as:

Piano Sound: SuperNATURAL Piano

while on all others (603 / 605, LX-7, LX-17) it says:

SuperNATURAL Piano Modeling

(The Roland sound engine for "super natural" sound is not sampling, but it is modeling the sound based on formulas, no sound samples.)

Does this mean the 601 does not include the sound modeling engine as the other ones do? Does it mean it uses sampling? Or is it some sort of hybrid or "simple" modeling compared to the others? Leaving out the word "modeling" is suspicious here.

There is no info on the Roland web site, they are hiding such "details" and rather overwhelm the viewer with all sorts of hyperbole. A clear distinction would be very good.

Answer 1

Carefully reading the description on Roland's site gives this answer:

The HP-601 uses sound sampling (confusingly also called SuperNatural by Roland).

The 603 / 605 / LX-7 and LX-17 use no sampling but instead the special Roland sound modeling technology. Roland labels that with almost the same name "SuperNatural piano modeling".

The detailed feature description shows that only on the 603 and up sound modeling is used. Amongst the "premium uprights", the 601 does not have the sound modeling generator. And none of the plain upright pianos have it.

Instead you could go for a stage piano, it would be cheaper for someone using only headphones and not requiring fancy loudspeaker systems. However, if you want the fancy sound modeling engine - you are out of luck, only the most expensive stage pianos include it (RD-2000 and V-Piano), and those are more pricey than a HP-603 (of course they have other features specificially meant for on-stage production but if you don't need that ...).