I'm interested in filters creating formants. It's not about human
 voice vowels or the sounds usually produced by by vocoders, but rather
 the formants associated with certain acoustic instruments, like cello,
 trumpet, trombone, French horn, etc.
 Probably nothing can beat the Yamaha FS1R when it comes to parameters
 shaping formants, but like many other digitals it can't process
 external sounds. I've read the specs for Doepfer A-104 Trautonium
 Formant Filter, A-127 VC Resonance Filter, and A-128 Fixed Filter
 Bank, as well as Analogue Systems RS-110 Multimode filter, and RS-360
 Vocal /Phase Filter Bank. Certain details caught my interest like the
 input sensitivity with A-104 that easily creates distortion and the
 RS-110 external resonance feedback chain where reverbed signals can be
 fed back. Some have extensive CV features like A-127, but unless
 programmability is desired, this is not a prerequisite since formats
 have fixed center frequences, bandwidth, etc, AFAIK.
 Unfortunately there are no audio samples for any of the above
 mentioned, so I like to ask if any of the list members have looked
 into/ experimented with instrument formats. Is there any reading to be
 recommended
 I'm new to this list, but it looks quite promising/Lars