diy high res midi/cv possible?

[kybertech]

I am looking to get into microtonal synthesis and am kind of at a loss.
Yes there are the MOTU interfaces, but that world require me to use a windows machine inbetween (or buy an apple, I use GNU/Linux)

So I am looking for a way to do this in a diy fashion.
There are chips which supply the needs but are expensive and probably cannot be used on a single/double sided pcb.

This is the chip I want if possible:
MAX5774UCB+D
might be fine since it has a TQFP package and sells as single pieces.

Since I wouldn't necessary need drift free conversion in the A/D path (just for tuning) I could use a audio A/D, but I don't want to. If I design such a thing it should also support things like LFO to NRPN.
I haven't decided upon a cpu yet... I think price here is secondary here, I would go for the fastest thing I can solder on a selfmade pcb. (Thinking about the Cortex-M3 since I already have a dev board for it)

Alternatives seem to be thin, and a preliminary research what multilayer prototypes cost defies the exercise, would cost me a small fortune.
Well there is the MOTM650 if everything else fails..

[elmood]

When you say "I/O" do you mean you want input and output, or just output?

What voltage range do you need?

How many outputs do you need?

Remember, that generally speaking you'll probably want to buffer the output of the DACs to create the correct voltage range and drive level, and to offer a bit of protection to the DAC.

[kybertech]

I want to have automatic tuning for polyphonic stuff, so yes I want to have input as well. (Zero crossing counter or FFT, on the processor, whatever works best.)
The reason I haven't written anything about it is that I don't really have an idea which A/D chip(s) would be best, there is no equivalent single chip with 32 A/D converters, the only ones are BGA and have to be ordered in multiples.

I could use 4 of these: MAX11046ETN+
But then there is the question if that meets my pcb layer and cpu restrictions (parallel interface).... Along with the more complicated analogue circuit requirements with multiple chips.

There are several other functions which I have in mind but those are optimal, some recording and mixing with very basic dsp would be nice.. I guess it wouldn't hurt to use it as a recording interface then, but again along with multiple peripheral lines and a possible cf interface and display the cpu requirements would soon be too much to handle on a selfmade board.

The level would be 5V so for buffering I am thinking of several midrange quad opamps, with a gain of 1. kiss principle, The fewer components the better?

I also thought of using a s/h unit instead, but I wouldn't want to loose the possibility of using it for audio output with dc offset.

An alternative solution would be to use the cpu only as serial interface and to the work on a extra board. Might be a better solution so it can be used with different projects. But I guess that ain't easy, there has to be a reason why serial audio interfaces are expensive.
On the other hand there isn't yet any reprogrammable / completely documented recording interface.

So long story short, I want a recording interface which can be used as dsp box and cv and midi interface... Isn't that too much to ask?


Another chip, as alternative for the 32 DAC:
DAC8568ICPW
Well at least it has 16bit

I think I'd have to settle for a board with 8 i/o then...