CS4397 dac

[JDMz]

Do you guys think i should ignore the Lampucera site mods and do these ones instead? How about bypassing the opamp? Is that better or should i keep the opamp? I plan to replace the opamp to the HDAM sun ones from here http://www.audio-gd.com/enweb/pro/diy/OPA.htm

[leo]

I was foolish to change so many components at once. Having read the http://www.lampizator.eu/ website and and also heard a friends modded DAC I decided to go for it!

I normally like to take things slowly and evaluate each change. I have recently built Peter Daniels Shigaclone transport with great results and wish I had taken the same approach with this project.



Should I stick with 150uf for the Oscon replacements and 220uf for the C3 and C18? And what about the tants, should I choose a larger value than 3.3uf?

Thanks Leo

Richard

Not foolish, just a little too eager

The original values for most of the decoupling caps was 100uf, the value isn't really critical so anything around 100-220uf should be ok

BTW, first easy thing to try is swapping C25 to a 10uf or 22uf cap, it looks like you have a big Oscon there, 150uf is too big for the CMOUT pin in my opinion, thats for the dacs internal bias
If that don't help much try changing just the other oscons and tants to general purpose 100-220uf, its worth leaving those two panasonic FM/FC caps until last and see what its like without the oscons and tants, we need to find a point where you start to hear improvements and then work from there

Very nice job on the Shigaclone

[leo]

Hi, I am planning to get this DAC and mod it according to the lampucera website AND the mods Leo showed. Will this have any conflicts?

Thank you

No, the caps don't seem as critical if using a valve output stage, one lot of caps may sound awful when the op-amp is used but tends to be far less awful when using the valves

Also with the Lampizator circuit your only using half of the differential outputs of the dac so don't take full advantage of the noise cancelling that this type of chip has

[leo]

Do you guys think i should ignore the Lampucera site mods and do these ones instead? How about bypassing the opamp? Is that better or should i keep the opamp? I plan to replace the opamp to the HDAM sun ones from here http://www.audio-gd.com/enweb/pro/diy/OPA.htm

Only mod I'd consider on the Lampizator site is the valve output stage, the use of lots of oscons as shown on there probably won't mate too well if using the op-amp, the lead length of those caps is way too long IMHO anyway

The valve stage sounds quite nice in a coloured way, some people will love it, others won't
I find it pleasant with this dac, it also covers a lot of the flaws, the op-amp stage makes things much harder to get to sound right

My advice is try both, see which you prefer

I've never tried that discrete HDAM Sun so no idea how it performs

[JDMz]

I plan to do your mods, and then get a HDAM opamp which was on the link of my last post. I am kind of new to electronics and need some elaboration on your instructions. What type of resistors are those 30k ones? (like wattage and tolerance) And the 68-75R.

Finally for the 150pf capacitors, would these work? http://cgi.ebay.com/Silver-Mica-Amp-...3A1|240%3A1318

Thank you

[leo]

The resistors are just phoenix MRS25 metal film 1% which I matched, nothing special, just what I had spare in my parts box, the 150pf caps are just cog ceramic, again its what I had so nothing special.
Mica is usually technically better but also physically larger, theres not a lot of room on this dac pcb, if you think the mica's will fit then they should be ok

[leo]

The resistors on the output are not critical, they are just to help with op-amps that don't drive capacitive loads very well, 22R to 100R should be fine

[JDMz]

Should the input capacitor be a good brand? like Mundorf or something?

What tolerance and wattage were your 30k resistors? Sorry for so many questions.. I am ordering now that's why

[leo]

It was 1:21am here so I'd gone to bed just after my last post

Any resistors I used was MRS25 0.6w 1% tol metal films, use the smallest you can find if it makes fitting easier, wattage is not really an issue here, obviously you don't need anything large over 1w, if the ones you buy come in packs I'd try matching them in pairs with your meter

SPDIF input cap is .1uf (100nf) Vishay MKP1837
My dac does not use output coupling caps, since doing the output stage mod in the differential (30k +150pf) output DC offset is near 0v
I'd only advise using no caps on the output if your pre-amp or amp has input caps just as a precaution

If your going to use output caps use any decent quality film type, I'm not sure what particular brand to recommend, everybody seems to have their own preferences for those

[gurusan]

How do you go about sizing output caps?