Vintage DAC for RaspberryPi audio

Picture of Vintage DAC for RaspberryPi audio
I was curios about some old school R2R DACs namely the BurrBrown PCM56P. They where used in the late 80's in some of the better CD players like SonyES222/DenonDCD1500/MaranzXY whatsoever. There is some discussion in certain forums about their more or less superior sound quality, compared to this and that chip bla bla... I simply needed to experience one myself.
So why not use one of these oldies with modern equipment ? Read on...

That is probably not exactly a step by step "instructable" you can just follow. Parts used are somewhat special and it's pretty advanced stuff I suppose. On the other hand all components used are big and handy through hole parts, making it easy to solder.
I would call this instructable "experience sharing". Hope you can find some ideas for your own projects or at least have fun reading.
Cheers, Mario :)

Warning !!!
Opening Hifi equipment might expose you to dangerous high voltage ! You should know what you do !
This kind of hacking can damage your superduper hifi equipment, especially speakers then used with that thing, Better run tests with cheap old stuff or old headphones !

What you need...
An old CD player, a RaspberryPi (with accessible P5 header), soldering iron, breadboard, handfull of logic chips, some wires, patience, an idea how TTL/CMOS logic works, and an oscilloscope could help to track down signals.

Results anticipated...
It plays sound nicely. For an internet radio this sounds really good. I have heard over my headphones so far, there the hights seem a little sharp, on the other side it plays a nice bass and clear mid. Not bad for a ~25 year old device.
Sound quality might have a bit of potential when using a modern and Elko free output stage, see last page for improvements.

Update 16.2.2014:
Added Pictures and schematic for I2S converter and how to hook up everything.
Added Pictures and schematic of the 6x clock multiplier.
Added annotated picture of CD player.
Slight changes in text.

Update 20.2.2014:
Fixed Bug in I2Sconv schematic, LRout was connected to V+ instead of Q2
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Termos30004 months ago


I want to do the same with Thomson dpl950 + RPI + MPD, but I do not know where to start;-)