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DAC build and output capacitor choice

post #1 of 9
5/21/10 at 2:11am
Thread Starter 

Hello,

 

I will be building a DDDAC-1543Mkii DAC.

 

However, I am having a big challenge picking the output coupling capacitors.

 

I am looking for help choosing the C2/3/4/5 output capacitors in the part of the schematic below (full schematic here, this is from page 5).

 

The designer of the thread recommends BG-N capacitors, or even Mundorfs, but it is not clear to me in what configuration, bypassed or not.

 

I have read everything which could give me hints (e.g. www.ecp.cc/cap-notes.html, http://www.humblehomemadehifi.com/Cap.html), but I am not converging towards a choice, really.

 

Will start with a single 3.3uF alu elco in the signal path (Nichicon Muse series, http://products.nichicon.co.jp/en/pdf/XJA043/e-es.pdf) without bypassing or R's. I took this choice from the ecp.cc site.

 

However, I am looking for suggestions how to enhance this output coupling stage for ~ US$10-15 for both channels. Anybody?

 

Untitled.png

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post #2 of 9
5/21/10 at 11:32am

http://www.41hz.com/shop/item.asp?catid=17&itemid=882

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post #3 of 9
5/21/10 at 1:10pm

Build one of these, then you won't need coupling caps:

 

http://www.diyaudio.com/forums/digital-source/23044-less-simple-i-v-tda1543.html

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post #4 of 9
5/21/10 at 9:23pm

I don't understand why those output caps are so large in the schematic.  Are you going to go directly into headphones?  If you are going to plug into any kind of amp, you can certainly go with a smaller value as you figured out from the guidelines on dsavitsk's site that you've mentioned.  However, at 3.3uF you can get a good film cap, like Audiocats suggested.  I'd only resort to electrolytics if you had to go with bigger capacitances.  Personally, I've never had luck with parallelling caps.  

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post #5 of 9
5/24/10 at 1:29pm
Thread Starter 

Hi,
 

Quote:
Originally Posted by AudioCats View Post

http://www.41hz.com/shop/item.asp?catid=17&itemid=882


And
 

Quote:
Originally Posted by grenert View Post

I don't understand why those output caps are so large in the schematic.  Are you going to go directly into headphones?  If you are going to plug into any kind of amp, you can certainly go with a smaller value as you figured out from the guidelines on dsavitsk's site that you've mentioned.  However, at 3.3uF you can get a good film cap, like Audiocats suggested.  I'd only resort to electrolytics if you had to go with bigger capacitances.  Personally, I've never had luck with parallelling caps.  


Thanks, always nice to see straigh-to-the-point advice :-) Yes, I will be feeding into a amp (home-built PPA v2).

 

I think I will order two from the site AudioCats is referring to. Also, I am tempted to be ordering two of these at a few bucks a piece, but these seem to be polyester, not polypropylene:

 

rifa2,2.jpg

 

(RIFA 2.2 uF, 17mmX41mmX36mm (LxWxH, pin spacing 37,5mm))

 

Would these work as well? Datasheet of these caps is here.

 

Will let you know how these turn out!

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post #6 of 9
5/24/10 at 3:30pm

Solen

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post #7 of 9
5/24/10 at 10:28pm

In general, polyester caps are not as good as polypropylene with respect to things like linearity, temperature stability, etc.  Go to Walt Jung's site and read his classic "Picking Capacitors" articles:

http://waltjung.org/Classic_Articles.html

 

Now, you don't always need the "best" capacitor in every situation, but if you can afford and can fit a better capacitor, might as well do it.

 

That being said, I used some Wima polyester capacitors as output caps once, and somehow they managed to sound worse to me than electrolytics!

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post #8 of 9
5/25/10 at 12:14am

the rifa PPS are great caps for signal path on a budget

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post #9 of 9
5/28/10 at 3:37am

For budget caps on a DAC/Preamp,  I like the Clarity Cap ESA's,  cheap and compete with some real expensive caps.   You probably only need 2uf,  what amp are you using?

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