Worst. FM. Synth. Ever.
If a question comes up about the DX9, it usually isn't long before someone will mention that it is the worst of the Yamaha DX synths.
Wikipedia echoes that sentiment with an interesting phrase:
"It is the least complex of the DX range of synthesizers"
Today there are two things that have sealed the fate of the DX9: the first is the above phrase (the origins of which we will describe below), the second is ironically the DX9's only real strength.
After the DX9, Yamaha produced several generations of popular 4 Operator FM synths. Such as the
DX100, which had iconic patches such as "Solid Bass" and "Talkbox". These synths were designed to be a lot less complex and expensive than the DX9. They had cheaper chip sets, simplified envelopes and reduced operator parameters. However, because the DX9 is really just a DX7 with features removed, it is not compatible with any of these later 4 Operator synths and cannot load or use patches from them.
So... DX9 owners had something less than a DX7 that in addition could not take advantage of the huge library of sounds created for the later 4OP Yamaha FM synths. This is pretty much the definition of the "worst of both worlds".
However, let's start by going back to the origins of that
Wikipedia quote, after which we'll look at how we can convert all those later 4OP sounds back to the good old DX9