Experience with this DIY DAC ?

[McCrackers]

Thanks Rich. Keep us posted.

[stokessd]

Originally Posted by RichLund

Hi Sheldon

I've just uploaded the schematic for someone else to see:

CS4398 DAC2 192KHz.pdf

BTW interesting site you have.

Thanks Rich, I appreciate the schematic. I'll post mine as soon as I finish my power supply portion of the schematic capture.

Thanks for the site comment. My site is getting old and long in the tooth. I should add some new content, but that involves actually doing something interesting.


Sheldon

[stokessd]

Looking at the schematic, I see a few issues. Obviously the DAC works, so I can only assume the schematic doesn't reflect the as-built configuration, or the CS8421 defaults.

Here's some note about things that I'm not sure of (they differ from my design based on the data sheets):

In the CS8416 portion, I set TXSEL0 and TXSEL1 to high so that the RXP3 input is put out on the TX pin. Since there is no input there, that pin should not be a noise source. Also the audio pin is open, and depending on the output format desired. (I ground it for left justified data when combined with U)

In the CS8421 portion, the schematic appears to be incomplete. In the schematic SAIF and SAOF pins are open. I haven't found in the data sheet what input and output modes that represents, but I defined the modes in my design:

SAIF: 1.96K to GND - left justified data
SAOF: 63.4K to GND - Left justified 24 bit data

Those are just my data buss decisions, you could easily use other modes, but those match my CS8416 and CS4398 outputs and inputs.

Sheldon

[stokessd]

IF anybody is interested, here's my DAC schematic. It's not complete, but has the bulk of the features I want. I've still tuning values and considering how to implement an input transformer with the CS8416 multiplexer. The output is a pair of Lundahl transformers.




Sheldon

[prairiemystic]

Originally Posted by stokessd

IF anybody is interested, here's my DAC schematic. It's not complete, but has the bulk of the features I want. I've still tuning values and considering how to implement an input transformer with the CS8416 multiplexer. The output is a pair of Lundahl transformers.
Sheldon

I looked at the schematic and found a few errors.

The CS8421 needs +2.5V power (VD), so R112 should be 220R and the clock oscillator powered from VCL, not VCD.
If you are netlisting, the wiring around C109 is missing a dot and ground; C61 needs power.
U5 (24.576MHz clock module) are notorious for polluting it's VDD. I've seen 10R or ferrite beads on the power to it, then 0.1/100uF decoupling. R10-12, R19-23 around 33-47R works well.

Otherwise it looks good

[Bill Fuss]

For what it's worth, the Chinese dac boards are set for standard I2S. I'm feeding the 8421 directly from an SAA7210 and CM4/19, a notable improvement over SPDIF.

[UV101]

Originally Posted by Bill Fuss

For what it's worth, the Chinese dac boards are set for standard I2S. I'm feeding the 8421 directly from an SAA7210 and CM4/19, a notable improvement over SPDIF.

I've done the same previously. Fed I2S from the SAA7210 on a Meridian transport (CDM2) into the filter on an external DAC.

Its works very well removing the change to spdif and back again but I understand its not very good over long distances. I only tried up to about 25cm.

[Bill Fuss]

I'm chewing on devising some type of switching arrangement to select between the 8416 and a PS Audio type I2S buffer circuit. It,s still just an idea at this point.

[stokessd]

prairiemystic -

Thanks for looking over my schematic, and catching my blunders. I wasn't sure if I would need data line resistors (the evaluation board schematics don't have them). I figured I'd need at least a jumper for layout anyway, so I added zero ohm resistors.

Regarding I2S:

Using i2S as an input is an interesting idea, and a good reason to do the inter-chip communication in I2S mode. I'll have to read more into it and what the transmission limits are. I'm using this DAC with an Airport Express, so the TOSLink and SPDIF are my main focus. In the last few years, I've been streaming all my music (lossless at home, low compression MP3 for the phone), and the user interface of iTunes (and the phone remote app) and the airport expresses is hard to beat.

Sheldon

[gabanyayaya]

To all,

This DAC comes in two version, with upsampling board 8421 and without upsampling board - closed jumper.

Can anyone explain differences in sound between these two version ?

Mine is w/o upsampling board. The ebay seller offer me the 8241 board for USD35 and the new version with PCM1798 chip for USD45.

Please let me know if this is could be consider a worthwhile upgrade.....???