[sdiy] Yamaha DXy DCO's

[WeAreAs1 at aol.com]

Just to clarify things (I hope), the original DX7 had two main IC's to 
generate its tone.  One IC was referred to as the Operator IC, and the other one was 
called the Envelope IC.  When the 4-operator synths came out, they contained 
just one IC that had all tone generation functions in one chip.  The 
DX21/DX27/DX100 are examples of this.  Not much later, they started producing a series 
of 2-operator, 8-bit FM chips, and used these in a lot of different 
consumer-type instrumants (the PSR/PSS/Portasound instruments).  They also were able to 
get computer soundcard makers and video game makers to start using this IC in 
OEM applications, and they sold a lot of FB-01 modules which contained this 
2-operator chip.  About this time, they introduced the second generation of 
6-operator FM units -- the DX7-II series -- which reduced all the tone generation 
fuction down to just one IC, added a few additional sound parameters, and 
upped the output resolution from 12-bit to 16 bits.  The next generation of FM 
chip was the one used in the TX81z/DX11 and a bunch of other very forgettable 
instruments (like the B200 and the TQ5).  This 4-operator FM chip had the added 
benefit of 8 different waveforms for the operators (not just sine waves), which 
greatly enhanced its ability to make more comlex tones with fewer operators.  
This IC was also sold to Korg for use in a few Korg keyboards and modules 
(the DS-8, etc).  Not long after that, they brought out the next, and pretty much 
final version of 6-operation FM IC's in the SY77, SY99, and TG77.  These 
instruments had the multiple FM waveforms of the TX81z, lots more sound 
parameters, digital resonant filters (on separate IC's), and the ability to combine PCM 
sample playback with the FM sounds.  They sounded fantastic, but by then, the 
marketplace battle had been pretty much lost to straight PCM sample playback, 
and Yamaha stopped making new FM instruments in favor of the more vanilla 
sample players.  Yamaha still sold a lot of little FM chips to computer soundcard 
makers (such as the Creative Labs Soundblaster series), but it disappeared 
from Yamaha's professional line.  They got around to bringing it back in the late 
19990's, with the introduction of the EX5 synth, which had multiple methods 
of tone generation, including a form of FM.  They are now producing a "plug-in" 
sound card (the PLG-150DX), which is a full-featured 32-voice 6-operator FM 
tone generator that can be added to any Yamaha synth that has their PLG plug-in 
slots (such as the S80, CS6X, etc.).  This soundcard is also used in Yamaha's 
very cool DX200 tabletop synth/sequencer, which has a bunch of knobs for 
real-time control over FM voice parameters (as well as good-sounding resonant 
filters!).  I have one of these cards in my MU100R sound module, and I love it.  
It has full compatibility with all old 6-operator FM voice data via sysex.  
It's very nice to see Yamaha once again supporting this great method of tone 
generation, even after their exclusive patent on the method has expired.  Kind of 
like Dr Moog with his Voyager synth, in my opinion.

Michael Bacich