Carat UD1 - Removing stuff from the output

Hi!

This is my first post here, i registered here for get in touch with the guys with the most knowledge in headphone stuff.

This is my first question:

This pic is from the datasheet from the PCM2704 IC which is used in the Carat UD1. After looking at the part vlues and stuff on the pcb of my DAC, i gonna assume that they just basically copied the example circuit in the ic's datasheet.

This is the output section:

C11, C12, R5, R6 in not really important, they are just form a lowpass filter on each channel.

I am the concerned about C9 and C10. They are 220uF electrolyte caps in the circuit. Now i don't really like caps in my signal line, let alone nasty electrolytes. R7, R8 is interesting too, they are 330Ohm resistors, i don't know what are they doing there. C13, C14 is just an 1uF Wima box cap.

So what is the big electrolytes purpose there? Can i scrap them? (soldering them out and jumpering the holes with a piece of cable) I don't care about DC offset. My analog signal passes through only one other cap in my system which is the input cap (1uF Wima MKP10) of my diy CMoy.

I got what you are saying about the caps but in the CMoy i have a "good"(?) quality prolypropylene Wima MKP10 while in the source i have a questionable quality unknown electrolyte so it would be better to remove the cap from the DAC and let it in the amp than the other way.

I dared to say that i don't care about DC offset because the CMoy's input cap gonna filter it out anyways. (i don't have a volume pot in my cmoy)
I am not planning on selling the DAC because i don't like to sell modded stuff, it is more like a moral issue for me, i am not too bad at soldering and stuff.

Anyways, according to the datasheet ( http://focus.ti.com/lit/ds/symlink/pcm2707.pdf ) the 330Ohm resistors after the electrolites have something to do with suspend function's (maybe it is the mute function?) pop noise.

Quote:

Originally Posted by nikongod 

I am not sure if they form a filter or not. On that note, I would not mess with them much until its figured out.

 

Famous last words. You should always pay attention to DC offset, even if you are using DC offset to your advantage.

 

If the cap in your Cmoy is after the pot, as is common, DC current will flow through the pot. If anyone but you plugs their equipment into your gear bad things will probably happen. Let the builder be ware. Perhaps most importantly (to me at least), and most realistically, when you go to sell the DAC you will have to convert it back to a safe piece of gear.

 

Rather than having the cap in the cmoy but not the source, why not have the cap in the source but not the cmoy? Following this method you can sell your source to anyone with no more effort than unplugging it and putting it in a box when the time comes to unload it. Alternately you could get a different amp which does not have an input cap and enjoy that. You could also get a source that has no caps in it and plug the cmoy in and have no caps in the signal path and enjoy excellent music. safely.