[Tubemooley]

I have been following this thread with great interest. This is a really killer project. I will be interested in any group buy for raw etch. Converter performance is influenced by the power supplies. Big shock there. Usually there is +5 VDD to power the digital side of the converter and any other digital IC's. Then there is +5 VCC for the analog side of the converter. Then, if you are running analog opamp circuits just outside the converters, well, they require their own supplies too (duh). Probably +/-15 VDC for those circuits. Now, ideally, those will all be completely independent separate supplies. But in practice, that can be difficult. And then, as we all know, linear supplies are generally more desireable than switchers. But I have found that switchers are more than suitable for use with converters. The noise generated inside those IC's can be far greater than any switcher noise. Careful IC de-coupling is highly recommended. So.... to try to answer the original question..... Multiple options exist especially if we're doing DIY. Check your shelves and pull out whatever will work. If you have nothing on your shelves, go to Mouser or Digi-Key or eBay. Now I have to back-track briefly. I believe Raphael is using the PCM4204 IC here. The VDD for that IC needs to be 3.3v. So there, I just complicated matters. But that's the way it is with a complex design like this. Really nice work Raphael. DANA.

[Tubemooley]

I just went back and re-read part of this thread. Looks like Raphael is using the PCM4104. And he's probably doing some of the power management on the board. Let's see what he says for power supply requirements. My big mouth got the best of me again. DW.

[pietro_moog]

i hope this thing could become as good as SSL alphalink!
it would be sooo cool to have  8 in & out. i'll make it become an interface with 4 ssl preamp, inserts, 2 phonos, monitoring outputs..
internal analog sum..   


i love SSL sound !

[baadc0de]

i hope this thing could become as good as SSL alphalink!
it would be sooo cool to have  8 in & out. i'll make it become an interface with 4 ssl preamp, inserts, 2 phonos, monitoring outputs..
internal analog sum..   


i love SSL sound !

Exactly. If these converters just "work" as well as the alphalink and we can manage cheap connectivity, like ethernet or USB3... to me that's a dream come true.

[deuce42]

And as Van Halen say "that's what dreams are made of"

Awesome stuff Raphael.

[rkn80]

Regarding the power supply:

You need the following voltages: For analog power -15V, +15V, +5V and for digital power +3V3.
The analog +5V are only needed for the ADC. The DAC board has a regulator on board that generates the +5V from the +15V rail.
On the analog board there was no space left for this regulator so I decided to build it externally. Therefore, the DAC board will get an additional pin to supply it with extern +5V too. Then you can decide if you want to use the onboard regulator and mount it or to use only one for all in order to reduce costs by not mounting the regulators on the boards. And finally the revision of the DAC board will get the same pin layout for the headers like the ADC board, so that they become interchangable.

Regarding the power supply itself: As you can see on the image I'm using a SMPS. This SMPS does only provide -/+12V and +5V which is ok but nothing special. I'm using this device always for testing and prototyping and do not have bad experiences for analog circuits except that 12V can be a little bit too less if you want to deal with high voltage peaks (I heard from people who like to drive +24dBu for 0dBfs out of their boxes). What you can't see is that the digital power is coming from the SHARC eval-board and will later be generated by a second smaller SMPS with only +5V output and regulated to +3V3.

Raphael  

[rkn80]

Hi,

please note: I've opened a Group buy thread for the ADC boards on the black market. You can find it here:

http://www.groupdiy.com/index.php?topic=37733.0



Raphael

[seavote]

im a little intimidated by this project as im an electronics newbie, but im thinking of giving it a try(when i finally get around to it) . i have one newbie question. will this and /or how does this a/d converter interface with my pc sound card.  s/pdif??
and if so(excuse my ignorance)if i use the s/pdif port on my sound card am i completely bypassing the cards own D/A conversion? ok so thats 2 questions.
you know what they say.
there are 3 kinds of people in the world those who can count and those who cant

[baadc0de]

The A/D and D/A boards communicate with I2S, which then needs to be format converted for usage by your PC. Raphael afaik uses a DSP evaluation board to provide this conversion, while there have been talks about an AES conversion board add-on in this thread. I am slowly working on a way to interface these to the computer via a cheap and simple ethernet cable, or alternatively, USB3.

[rkn80]

Yes there is already a design for a AES in/out board ready to make. But you can also use the ADAT or S/PDIF receiver and transmitter boards flying around on this forum and on the internet because they all use I2S and you can configure the ADC and the DAC as master or slave on the I2S line. I'm only using the eval-board because it is easy for me and I can concentrate on the device under test because I know that the eval-board is doing it's job.

I also want to do a design a wordclock in/out. I see a certain need for it. Perhaps that will come first because standard interface boards like ADAT and AES are available from other DIY'lers. But not sure, depends on my free time the next weeks...

Raphael

[Biasrocks]

I also want to do a design a wordclock in/out. I see a certain need for it. Perhaps that will come first because standard interface boards like ADAT and AES are available from other DIY'lers. But not sure, depends on my free time the next weeks...
Raphael

Yes!

External WC is critical for integrating multiple converters.

ADAT SMUX @ 96kHz is all I use here, I haven't seen any interface boards that will allow that.

Some info here

http://www.wavefrontsemi.com/index.php?id=11,10,0,0,1,0#productdocsoft

http://www.wavefrontsemi.com/UserFiles/File/AL_Info/ADATOptical96KAddendum1.0.pdf

Mark

[rkn80]

Mark,

see reply #202. Mikkel states that his boards do work with SMUX.
Because my boards offer I2S input and output you can connect any digital audio interface you want ADAT, AES, whatever...

Raphael

[jdbakker]

Mikkel states that his boards do work with SMUX.

They do, sort of.

As far as I can tell, Mikkel's OptoRec is a direct implementation of the Wavefront ADAT receiver chip. This means that while it will accept S/MUX streams (and set a flag to show the stream is S/MUX), you still need an external converter to multiplex the two 48k channels into one 96k channel. This could be implemented in a CPLD/FPGA, a fast enough microcontroller/DSP or a lot of discrete logic.

JDB.

[jackies]

 
Stupid question or not...
Doesn't any soundcard use I2S? Would it be possible to just hack any soundcard and hook these converters to it?

[jdbakker]

Doesn't any soundcard use I2S?

Some do, some don't. Cheaper ones have all-in-one chips with the ADC/DAC integrated in the PCI bus interface chip. While I2S is more prevalent, some cards use other digital formats to talk to their converter chips (mostly left-justified, rarely right-justified). I do believe that the PCM4x04 chips support these modes as well.

Would it be possible to just hack any soundcard and hook these converters to it?

Possible? Sure, if you can find the right traces and manage to solder teeny patch wires and possibly buffers to them. I know I don't have the fine motor skills for such brain surgery, but others might.

JDB.

[rkn80]

It is not so difficult to hack a soundcard. Only one condition: The soundcard must use chips where you can find enough info's about on the web. Let's assume your sound card uses a DAC that is fully hardware controlled (no SPI control or whatever) then you can easily figure out which signal type (I2S, left-justified etc) is sent to it and you can add your own device instead of the original chip. There are informations about many standard 'bridge' chips like the envy24 on the web, too. I did susch a hacking once for a card. You only need a little bit courage and the luck to find enough info about the hardware. More difficult is the game if there is some OEM stuff or programmable logic on that card but still doable.
But the main problem is: Normally you don't know enough about the soundcard hardware until it lies on your desk and you can inspect it. So you either need to buy one your you need to risk to destroy your currently used soundcard... 

Raphael

[Laran]

Hello,

my first post on the forum - though I've been a lurker for some time, reading, learning and being inspired by all the creative projects being developped here.

I am very interested in th ad/da project, and would actually like to build quite a few channels of it if I can manage it - it is a happy coincidence that this project is reaching critical mass just now when I was looking for exactly this!   

I don't have much experience yet with building DIY audio units, but have been wanting to jump in and learn for years.  Now seems like the right time.

I do have some concerns (being new to it all) - while I'm not too worried about the soldering,  I'm not clear on how most of the interfacing is going to work - power supply?  connecting the various boards together?  getting it connected to the computer?  I'd like to get 96k from these converters - how is smux implemented?

Are these things going to be coming down the pipeline?  My main concern is to be left with a stack of beautifully assembled pcbs and no idea how to make use of them.   

Is the first batch that is getting ordered up exclusively for the AD right now, with DA to follow later?  and hopefully the other components to get it all running?


Apart from these concerns - congrats and thanks for all the tremendous work that has gone into this project already - I look forward to participating.   

[Kingston]

Oh for the love of god please build at least a single tubescreamer before attempting anything as sophisticated as a full blown 96khz multichannel AD/DA with SMD sizes!  

[baadc0de]

Oh for the love of god please build at least a single tubescreamer before attempting anything as sophisticated as a full blown 96khz multichannel AD/DA with SMD sizes! 

Agreed. I've done a few DIY builds but am still going to offload the SMD-ing to someone else who does it for a living. Not that it can't be done, but I don't trust my abilities with something as complex as this one

Laran, do you know any electronics guys who repair modern equipment with SMD elements for a living? Maybe get in touch with someone from a local electronics forum or something..

[deuce42]

Laran

Welcome to the board. Dont be put off with posts that might be a bit blunt and direct. Some members here can actually be very encouraging and nice. I do agree it may be worth your while with a few tiny projects first though-  smd is another ball game.  

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