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stokessd 12th August 2011 12:13 AM

CS4398 Based DAC Blank Boards For Sale
 
3 Attachment(s)
I've designed a DAC somewhat similar to the gigawork DAC in this giant thread: http://www.diyaudio.com/forums/digit...iy-dac-78.html

It uses a CS8416 Receiver Chip, followed by a CS8421 Asynchronous Sample Rate Converter Chip which is clocked via a low jitter oscillator module with a finesse regulator circuit on the power line. This feeds a CS4398 DAC chip who's output drive a pair of Lundahl transformers. It has both analog and digital raw supplies fed from different power transformer windings and contains seven regulation stages with liberal decoupling at the chip pins.

It includes both TOSLink and Coax digital input, and headers for two additional off-board inputs.

The transformer output will accommodate both single ended and balanced output.

Some more information, photos, schematic, layout and parts lists are available here: Sheldon’s World Blog Archive Another Audio Digital-to-Analog (DAC) is Born


Pictures of the boards are shown below.

A blank board costs $40 including shipping within the USA. I'll also solder the three audio chips in place for you on a board for $85 including shipping within the USA. Foreign orders are welcome, but the shipping will cost an additional couple dollars.

If you are interested, I can be reached here, or at stokes(at)quadesl.com


Thanks,
Sheldon

jmillerdoc 12th August 2011 01:51 PM

Is the big square on the board for an encapsulated toroid transformer? If so, what is the ratings required? Does it power everything?

korben69 12th August 2011 10:05 PM

Sheldon’s World Blog Archive Another Audio Digital-to-Analog (DAC) is Born ;)

stokessd 13th August 2011 12:14 AM

Quote:

Originally Posted by jmillerdoc (Post 2669476)
Is the big square on the board for an encapsulated toroid transformer? If so, what is the ratings required? Does it power everything?

Yes, the square is for a PCB mount toroid transformer. IT's a 10 VA toroid with a pair of 7 volt secondaries.

If memory serves me right, the DAC consumes about 2.5 watts of power.

Sheldon

johnm 13th August 2011 01:35 PM

Hi Sheldon.

Is there provision on the boards for changing the 'speed' of the DAC? i.e. Single speed, double speed and quad speed settings (depending on the bit/sample rate of the files being played)?

Cheers,

- John

stokessd 14th August 2011 12:58 AM

John-

Not currently, all sample rate materials are upsampled to 192KHz, so as far as the DAC is concerned, it's always playing at 192KHz.

The sample rate converter chip could be omitted and then the clock lines could be run from the receiver chip to the DAC chip, and then you would be able to change the DAC "speed" by fiddling with the resistors around the DAC. That's a big change to the design, and I'm not sure this board would be an ideal candidate.

Sheldon

johnm 14th August 2011 01:09 PM

Thanks for your reply Sheldon - I'll regretfully have to pass on this I think. I prefer to be able to select the correct speed for the sampling rate in question (i.e. after experimenting with the Gigaworks board I personally think 16-bit files sound best on the single-speed setting, etc). Many thanks,

- John

Pano 14th August 2011 02:19 PM

Very nice design. I'm sorely tempted, even tho I don't really need one. :)
Good choice on the CS4398. It seems to be particularly well suited to driving a transformer output. Not sure why, but it works well. I like the care (overkill) you've taken in the PSU.

Did you trim the output circuit parts to fit the Lundahl iron? Maybe you said, but I missed it. Just thinking that is another transformer were used, then those values might need some tweaking.

stokessd 14th August 2011 07:29 PM

Pano -

I have tuned the output slightly, but I'm not using most of the filter network capability that I added to the board on my prototype.

Thanks for noticing my over the top power supply and regulator work. If you are really into power supply overkill, the generic LM317 linear regulators can be swapped for higher performance LT1086 regulators.

Also the cost of the board is small potatoes compared to the cost of a pair of sweet lundahl transformers on the output.


Sheldon

jean-paul 14th August 2011 08:14 PM

The board looks OK but the use of only Lundahl (input!) transformers limits its use. I am also tempted though as the CS4398 really shines with transformers...


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