[sdiy] poly six problems

[Bob Weigel]

All the units using the CEM3394 have some kind of tune feature I'm 
sure.  The SCI units you hit record and while still holding it "6" to 
initiate a tune.  Otherwise the six-trak will auto-tune every half hour 
of idle time I think it is and make a corresponding pop which is no good 
:-).  wish I could turn that feature off.  You should be able to turn up 
a deal on an AX80 that has some problems with the aforementioned 
soldered interconnects on the display boards.  I got one expecting that 
but of course as my ...can't even call it luck anymore...whatever it 
is...would have it... there were two totally broken circuit boards and 
fortunately I'm pretty good at repairing that kind of problem.  Later 
one joint I missed started acting up and I just repaired it the other 
day so it's 100% again.  I've written most of a set of patches for it. 
Kind of a fun machine for certain types of sounds.  Hate it for others.  
Decent clavs, good for ethereal pads and organs, and punchy synth 
bass/brass, bad  for things with a sweet tone in general I think I'd 
say.  Just lacks the character due to the dco's probably

Btw I updated for clarity my ax80 page at 
www.imt.net/~sounddoctorin/synthtec etc.  I scooped the archived article 
written by someone at Akai apparently years ago.  They were not very 
good in how they communicated things.  They seemed to think the 
oscillators were analogy.  Rather at best what we have here is a pulse 
driven op amp or some such thing...which doesn't qualify as an 'analog 
oscillator' :-)

The only real digital control that happens on any instruments I'm aware 
of that have real vco's, is auto tune routines and control back from 
patch storage.  The Yamaha CS20M is interesting in that it has two 
colors of knobs.  Well white and a color. The white ones are not stored 
and they include the two pitch controls and PWM LFO, GLIDE, and Initial 
level controls as I recall.  Thus the pitch is totally zipper free.  
Which is a beautiful thing. :-)  When you turn pitch knobs on a prophet 
of course you hear incremental movements.  When you move a pitch wheel 
on a kawai SX series...MAN DO YOU EVER HEAR IT!  My 210 isn't so bad but 
I just worked on a 240 the other day.  I was checking to make sure the 
4049's were all ok...it has like only a couple increments each direction 
on the pitch wheel!  Anybody else got one of those? Is that normal??

Anyway digital control stinks but it's necessary to implement storage on 
a budget.

My way of doing it ideally would have been different.   To create a 
performance machine with storage, there should be analog switches that, 
when a slider/knob is moved, only activate after a programmable time 
delay (or even have the processor step values over the delay time to 
*meet* the knob's position after that delay... either way the user has 
opportunity to avoid a sudden huge transition particularly at 
self-resonance ;-) )  allow the user direct control of pitch, resonance, 
cutoff and pulse width parameters at least!  That's the real weakness of 
a machine like the Chroma polaris.  BAM you're at peak resonance!  Or 
you just hear gritty resolution on varios things.  Resonance is actually 
a slider that functions as an 8 position switch as I recall.

Anyway, so in my ideal synth, once you stop moving the slider and hit 
'store' the computer takes it's best crack at remembering what you had 
dialed up but of course it wont' get it perfect, just close.  Is that a 
great idea though?  One of these days..I'm going to try to do that with 
one of these dk600 boards I've got lying around; building 6 independent 
vco's maybe even w/independent tune knobs in unison mode with lock to 
one control in poly. :-).  I may have a working QS8 board also here 
now.  I was thinking..hmm.  Cut a display into this old Fatar junk lying 
over here...and a button and controller setup into a face plate that 
extends up a ways so that there is room to place the qs8 board below and 
the dk600 board above...and just tap the MIDI of the qs8 to drive a pic 
assigner program... and then have the ability to layer those two or even 
mix the audio of the qs into the mix w/ the analog vco's!  That's be 
interesting.  The DK600 has dynamic filtering with respect to perceived 
note number in order to waveshape the square waves coming in from the 
divider/assigner chips as I recall.  So basically the whole audio out of 
the qs would be fed into a 6 voice mix where each voice reflects it's 
assigned note numbers filter coloration plus the vcf and vca w/mods.  
Could be...really interesting!  -Bob

bill bigrig wrote:

>Howdy,
>
> Good info on the AXs. I believe the 80 has DCOs. I
>KNOW the 60 has VCOs, or at leat that's what it says
>on the front. And a "tune" button ala Prophet-600. It
>is almost a direct clone of a juno-60, but with MIDI
>and an interface for running the 900 series samplers
>through it's filters. Very versatile axe. But 1 VCO
>per voice. That's why I'm trying to find a bargain
>AX-80. All my old synths seem to be single osc. units
>except the P-600 and T-8. With 2 Juno 60s and an
>HR-60, I'm set for 1 voice stuff.
>
>
> 
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