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