MOTM

Speaking as one who has tinkered with a couple of GX-1s, and owns a 
relative of it (the EX-2), I can comment on a few things:

   The machine, as well-built as it is, as great-sounding as it is when 
the beast is working properly, is not worth $100K (in AUD or USD).  I 
would put its "best possible" value at *maybe* USD$25K.  It is very hard 
to repair, mainly due to the fact it has several hundred epoxy-potted 
submodules.  These are incredibly difficult to reverse-engineer, let alone 
repair.  In addition, there are dozens of custom ICs in the key assigner 
circuits, old, strange devices that run an weird voltages.  Again, really 
tough to repair--Yamaha doesn't have the materials (or the interest) to 
fix them.

   Of course, this didn't stop me from tearing apart the submodules that 
comprise a GX voice.  The filters of course became the MOTM-485 and 
MOTM-475, just as my investigations of the CS-80 filter led me to make the 
MOTM-480.  I've figured out the VCO, the waveshaper and the filter & 
amplifier EGs as well (though save for the filter EG none of them will 
likely become MOTM modules).  As I have described before, the filters of 
the GX and the CS-80 are not the same types.  They have similar 
configurations (LP->HP for GX-1, HP->LP for CS-80) and in fact Yamaha uses 
this "tone color circuit" in many organs from the 1970s, starting with the 
GX-1.  Still, when calibrated properly the filters of GX vs. CS sound very 
similar.  This was due to Yamaha's rather strict control of Fcv and 
maximun Q factor.  In the MOTM versions of my GX and CS filters these 
Yamaha limitations can be overdriven or even removed entirely.

   Anyway, back to the GX-1.  The things that makes it nice to play are the 
user performance controls, most of which made it to the CS-80.  Of course, 
things like the twisting of the expression pedal to vary modulation, or 
the knee lever to cancel a preset (remember the GX-1 is a synthesizer 
masquerading as a stage organ, and has registrations, preset pistons and 
the like) can't exactly cross over to a "portable" CS-80, but it is still 
a good translation.  Ihe GX-1 (and EX-2) do have a touch vibrato upper 
manual action: press a key and wiggle it side to side, the more wiggle the 
more vibrato.  I sometimes wish the CS-80 had that, but assigning LFO mod 
depth to the aftertouch works nearly as well.

   Of course, if someone actually bids *and pays* (this is ebay, remember) 
the asking price, they can afford to hire, say, me, for $100/hr plus 
expenses to keep the thing running. ;)

   I now return to hacking the Voyetra-Eight while the turkey is in the 
brine. ;)

Crow
/**/

On Wed, 23 Nov 2005, Dino Leone wrote:

> Unbelievable!!! It's been over an hour now since I saw those pictures, 
> and I still haven't recovered.... and I was "only" dreaming about a 
> CS-80..... if this isn't the most beautiful synth ever made....
>
> Dear fellows, this is one of those moments, where it would just be very 
> handy to have unlimited financial resources! Hmmm. Actually, it's all 
> Paul's fault. If he hadn't made that MOTM-480, I wouldn't be obsessed 
> with that sound.  :-)
>
> Happy Thanksgiving to everybody here in the States!
>
> Dino