PAiA 9700 now midi2cv8 mods

[tomg]

Hey Tony,
 
> >However you have to hold the lowest key to set 0V when you turn it on.
> If you build it
> for v/hz you can just turn it on, no need to hold a key. This is minor
> but inconvenient
> for v/oct users if your rack if more that say 6' from your master
> keyboard.
> 
> How about adding a -3V offset to the CV summer of your VCO, my TB3030
> allows you to do this very easy by using a pin on the pcb and linking it
> to +12v.

That works doesn't it? But I would rather the cv8 came up correctly than
modifying all of my oscillators. We really need a fix for this.

> >While we are talking about this...Tony A..could you please tell us
> again what
> you replaced the stock DAC with and the difference you observed.
> 
> I did several mods to mine. I used a ref-02 to generate the +5V
> reference for the DAC with no trimmer, OK so you don't get exactly
> 1V/oct this way, but most VCOs can be trimmed to accomodate this. I
> ditched the LM324 and used a OP-27 for the DAC transimpedance amp. The
> space taken by the 324 gave me enough room to put the ref and the op-27
> next to each other. I also changed the negative rail supplying the
> de-mpx to 0V6 by a diode and resistor off the -12V negative rail. For
> the DAC I used a higher spec'd device from AD. I think its number was
> DAC-08HP, this gives 1/4LSB error, still not brilliant but a lot easier
> than squeezing a 12bit part in the space. This does sound audibly
> better, and I have not detected any off tune notes by ear. Although my
> tuner does find out of scale notes, by 2 or 3 cents.
> 
> My main quibble with the midi2cv8 is that before I use it in my
> sequencer based set up, I have to wiggle my pitch bend lever after I
> turn it on the very first time. Otherwise, the unit folds the keyboard
> over so that the highest note is in the middle of the keyboard. all part
> of the same problem Tom mentions.

Thanks Tony. You almost started over didn't you?

-tg