OK this ought to be fun: gutting a DMPA

mshilarious

mshilarious

Banned
So I've had this ART Digital MPA that I haven't used in a few years; it developed a buzz on the mainboard that I just couldn't track down as it's a bit tough to get to everywhere in terms of test points when it's all assembled, and since I have my own pres that I can build in less time than it would take to fix I just stuck it up on the shelf.

But yesterday I decided to pull its digital PCB and see if I could hack that into a standalone converter. Got the schemo from ART (they are standup dudes); I have the original AK5394 ADC (I understand later they swapped for something cheaper) and it was nice, so this should be good. There are two IDC connectors, one is five pin which is +/- L/R and +5VDC; the other is a bunch of pins that staring at the schemo carries encoding for sample rate--all high/low switched pins, I think.

Should be fun!

My daughter took the camera with her out of town today, so maybe some pictures tomorrow :)

PS if anybody wants to buy the rather beefy-looking transformer out of this box, or the VU meters (2u high min), make me an offer . . .
 
First update: after careful study I see that the rotary encoder on the front panel which I thought was sending control signals to an MCU which is on the mainboard. D'Oh! I thought the direction of the serial data flow was the other way only, to feed the LEDs on the front panel.

That's OK, I think I can hack the required output to bypass the need for the serial feed. The DMPA has a lot of options: SPDIF vs. AES out, six sample rates, ADAT clocking, etc. I only need four rates and internal clock, so I should only need two switches (44.1/48, SS vs. DS).

I see that the SPDIF driver IC (DIT4192) takes a serial data input. Grrrr. That chip has a hardware mode though, so I will have to hack it to enable that. Of course that *has* to be on the only chip on the board that is SSOP rather than SOIC :(
 
I'll be watching too. I chronicled my DMPA murder and re-animation on here a while back, I think, but I was working from a more dark ages perspective. Mine actually sounds better now to my ears after swapping some opamps.
 
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