[sdiy] Unique sounding modules that can't have voltage control?

[Tony Allgood]

MB > Where you will probably end up is the long obsolete LMC835 chip 
which was the usual solution before we went DSP.  But that is digitally 
stepped so no use for voltage control.

There's also the (very much obsolete) LM1040. Mainstay of many a TV in 
the day. DC control over bass, treble, volume and a loudness profile. 
There's a simplified schematic in the datasheet.

The TDA1074 is also similar IC but only does the tone control part.

Tony