DIY DAC for a total newbie? aka - calling GV

ShinAce

Ok, so RJaco built a beautiful set of monitors for his son...lucky kid. ****, I had to build my own freakin set of monitors for myself(parts and box weren't nearly as nice) when I was 14. Anywho. Both of us are using the analog output on our PCs for sound.

Then it hit me like a brick to the temple. I swapped the motherboard on my PC 2 months ago with one a buddy tossed my way. It has SPDIF in and out. I'm only looking at the SPDIF out.

RJaco has better skills at building stuff. And better access to wood. However, I got mads digital skills having done some simple digital circuits. I'm also a line level audio king, dabbling in pre-amps and headphone amps.

I won't have the required chips on hand, but I have most of the rest. I'm a big fan of the NE5532 for an opamp, but who really cares.

Is there an easy and cheap DAC that I can build? Is there a cheap DAC that people know of? I could always look for a common and good one online.

What do I need to know before using the digital out? Where do I find some good info on using the digital output. Mine is RCA and I even have my first FLAC album on the computer.

One last question. Can I build a digital crossover? How is the digital signal encoded is what I'm asking to figure this one out.

Systems

I happen to have a DAC in my parts bin that only needs a power supply,chassis and connectors etc.It uses a Crystal CS8412 input reciever,CS4390 24bit DAC chip and a very nice discrete analog stage.(The CS 4390 is no longer produced but was in part developed by Meridian and used in their products and Audio Research's highly regarded DAC's).It is mostly a DIY effort ,I etched the digital board but the analog section was lifted from a hi end pre amp.It will only accept a SP/DIF input.I can upload some pics if you are interested,and oh yeah its a freebie.


If you want USB capability I also have this neat little device I no longer have need of.Its a fully functional BurrBrown USB DAC.http://focus.ti.com.cn/cn/lit/ug/sleu049a/sleu049a.pdf It is setup to drive mini headphones but you could also drive a pre amp with it.You might even add an output buffer stage using your prefered NE5532.

Ender

Are you talking about from scratch? Including your own PCB? http://www.google.com/search?hl=en&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&hs=lWx&q=DIY+PCB&btnG=Search

Systems

The first pic is the DIY unit,the 3 separate boards are the 5 volt digital regulators,Input receiver and Dac chip,analog stage.

The second pic is the BurrBrown USB DAC.


If you want to build something with newer a generation chip set the Buffalo DAC and IVY boards from Twisted Pear IMO would be a great choice.
http://www.twistedpearaudio.com/digital/buffalo.aspx
http://www.twistedpearaudio.com/linestages/ivy.aspx
http://www.twistedpearaudio.com/digital/wm8804.aspx

ShinAce

Wow, I realize how new I am to this now. I do have double-sided copper boards on hand so I can etch my own.

Firstly, what's the point of USB anyways? I always figured it was to have digital output when the PC didn't have SPDIF out. It looks to be just an interface.

Secondly, yes I will take that old DAC you got there. I'll send you a PM for details.

Systems

ShinAce wrote: »

Firstly, what's the point of USB anyways? I always figured it was to have digital output when the PC didn't have SPDIF out. It looks to be just an interface.

For laptops etc that don't have S/PDIF outputs.Aswell this little board can be powered by the USB bus thus not needing an external power supply.

yes I will take that old DAC you got there.

SOLD

Here is some study materials for you.;)http://www.datasheetcatalog.org/datasheets2/64/644753_1.pdf

Mike21

SPDIF out from a computer is from the soundcard.
USB (and Firewire, I2S and Bluetooth) bypasses the soundcard. People w/ so-so soundcards (like my Soundblaster Live! 5.1) go the USB route into an external DAC. People with really good soundcards (DAC and noise shielding) go directly from soundcard to preamp/processor, integrated amp or receiver.
Maybe look at the Scott Nixon DIY DACs

ShinAce

To cap off the thread:

My motherboard is the one that can output(and input) in SPDIF. It supports 44.1KHz and 48KHz SPDIF(or PCM). My understanding is that when the output is SPDIF, analog is cut-off. I simply hope that the mobo's soundchip is able to always output to straight SPDIF(no Dolby) as to avoid swapping cables.

I have some Apex headphones that sound great and I can use that to compare the different output modes and their sound. At the end of the day, the chain will be: SPDIF out from PC --> DIY DAC --> (optional DIY electronic crossover) --> amps --> DIY bookshelf speakers.

The build will be easy. I have a variety of transformers that could do the job. The case being used is a burnt out Pioneer amp. I'm using the amp for its case, power cord, power switch, RCA jacks and PS filter caps(2x 3300uF-35V). It also has a switched 1/4" headphone jack that will be implemented. I have spare copper boards, rectifiers, and coupling capacitors to make the package nice and tidy.

Total cost to me....0$

Improvement in sound....we'll see

Gratitude owed to GV....priceless

p.s. random thought of the day: Am I the only one that wants to build a subwoofer loaded horn out of snow and coat it with ice? I'm thinking a 15" woofer and a mouth roughly 6' x 8'. Either molded from the ground up or dug from a mound.

zingo

ShinAce wrote: »

p.s. random thought of the day: Am I the only one that wants to build a subwoofer loaded horn out of snow and coat it with ice? I'm thinking a 15" woofer and a mouth roughly 6' x 8'. Either molded from the ground up or dug from a mound.

Nope.

ShinAce

Now that I think about it, the analog section looks interesting.

Firstly, two transistors are bigger than the rest. I'm guessing the 4 small ones are 2n3904/3906 or BC549/559. It's obviously designed to dissipate more heat than most.

Secondly, it appears to be push-pull. I only say this because I already know it's class A.

Lastly, are the large electrolytics on the analog board for filtering? That's a lot of reserve power on hand for such a small current. Nor do I recognize the bright blue guys...some kind of mylar cap?

Systems

ShinAce wrote: »

Now that I think about it, the analog section looks interesting.

Firstly, two transistors are bigger than the rest. I'm guessing the 4 small ones are 2n3904/3906 or BC549/559. It's obviously designed to dissipate more heat than most.

413/415's in the differential input stage,2N5679/5681 are the metal cased output trans.

Secondly, it appears to be push-pull. I only say this because I already know it's class A.

All BJT dual differential, full complimentary push pull.;)

Lastly, are the large electrolytics on the analog board for filtering?

Power supply decoupling.

Nor do I recognize the bright blue guys...some kind of mylar cap?

Polystyrene