I’m sure it was a DX7. Back then that was one of those sounds that it was very possible to play with the timbre change in a very similar fashion to the actual acoustic instrument. That plus the 1:1 control via breath made the transition complete. Rather than controlling the volume with velocity, the “how loud” could be controlled by air pressure on your BC... on the keys you could use aftertouch to bend pitch and apply timbre change (Modulator index) that was a key to getting to “sing” like the acoustic harmonica.... changing both pitch and timbre simultaneously with a playing gesture. Those with a good ear and sensitivity could have you thinking you were listening to a seasoned harpist.

The silly arguments that typically follow about it can’t do everything you can with a harmonica follow... that’s not the point, the fact that you could pull off an eight Measure interlude was/is quite an accomplishment. But back then, and even today, you’ll have a million opinions about “should you use synths to replace...”, or the “they can’t replace...” Yada, yada, yada... fact remains, the DX7 harmonica was one of “those sounds” that started arguments, and it was improved on the DX7II... which was released in ‘86, btw.

Thank you very much for you reply, Phil!

You are really awesome person with a lot of knowledge.. I wish I was too..

I do not have a Breath Controller but I 've been thinking about buying one. If I am getting it right, I can set aftertouch to perform the transition between the notes? Supposing the polyphony is set to mono..
I am still a bit confused about that timbre change.. and furious too… As a big fan of the 80s' sound I've been trying to get that "Sara" harmonica for some time..and still no luck.. 🙁

If I am not mistaken, "Sara" is 1985, so it must have been DX7 MkI.,

Timbre change in FM is handled by changing the output level of the Modulator. In the original DX FM you had no filters, so all timbre change was generated organically - the more output from the Modulator the more sidebands (harmonics) generated. The reedy tones of harmonica, accordions, organs, are one of the real strengths for FM. Wooden, metallic harmonic relationship work well in FM, as well. So well, in fact, they can be stunning in their own right. So much of the craft of emulation is getting the mathematical relationship (balance) of the harmonics correct.

Bell tones can be absolutely nailed, even before you construct the percussive clanger— hearing just the pitched tones of the bell by them selves is really pure musical math. Tubular bells, Grand Marimbas...

Like a fingerprint is a unique set of lines, the harmonic content, the balance in levels of the harmonic series identify a sound for our ear/brain. When the volume between the Fundamental and the next half dozen harmonics in the series, you start to believe you are hearing the acoustic instrument. It’s then about “how” it’s played, is the phrasing believable...

Thanks! FM synthesis seems hard to program..
I'm just trying to figure out which controller I should use to get the timber change. All controllers are editable in Cubase..
There is a preset "HRMONICA2 BC", that is probably the patch that was used on "Sara".