PAiA 9700 now midi2cv8 mods

[Tony Allgood]

>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.

>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.

Regards,

Tony Allgood who has just bought a new modem because the computer was
struck by lightning yesterday. 50UKP... ouch, the cost is shocking
enough!