[earplay]

Cognizenti,

Here's the story. I've been tweaking my inexpensive dac and have been pleased thus far.

It's a Trends UD-10. I removed it from its metal box. I replaced the earphone jack with two Vampire RCA jacks. I wired them with silver wire to the output resistors that immediately follow the output caps.

Here's my first question: would the SQ improve if I replaced the stock output caps with larger, higher quality caps?

If so, can I bypass the resistor and further improve the SQ?

My thinking is that the resistor is in place to keep the stock cap from discharging too fast. A larger cap may not need a resistor because it holds enough power that it would not discharge even without a resistor. If that is the case, and if all other things are equal, then I could connect the cap leads directly to the RCA jacks. This would simplify and shorten the signal path.

Sooooo, how far off base am I???   


earplay

[randytsuch]

Cognizenti,

Here's my first question: would the SQ improve if I replaced the stock output caps with larger, higher quality caps?

If so, can I bypass the resistor and further improve the SQ?

earplay

A better cap probably would help.  I did have a tube preamp once, where upgrading the coupling caps did not help it, but after I upgraded the power supply, then the coupling caps were an improvement.

IOW, depends are the quality of the signal going into the caps.  If the DAC is generating a reasonable output, then upgrading the caps should get you closer to hearing what is coming out of the DAC.  A higher value may not be necessary, the higher value will lower the frequency of the signal getting through, but if it is low enough already, then an higher value cap does not buy anything, and might even hurt.  They would be larger, and harder to install.

I would not bypass the resistor unless I know what it was there for.  Normally, people put in resistors for a reason, and it's not a good idea to short one out, unless you know what you're doing, and how it will change the characteristics of the circuit.

Randy

[earplay]

Thanks, Randy.

I supposed that bypassing the resistor would chancy. I was hoping that is was there only to keep the cap from discharging too quickly. Since I do not know exactly what it does, I guess I better leave it in place if I want to keep the dac healthy.

Appreciate your reply.

earplay

[JoshK]

Output caps followed by resistors from signal to ground at the output connectors?  If so, that is standard high pass filter.  You shouldn't alter the resistors in this circuit since the filter freq is dependent on that value, not to mention the output impedance is also partly dependent on this value.   You ought not to alter the value of the cap either unless you understand the trade offs.  If you want to replace the cap with your favorite cap, that is probably ok, but I'd leave the resistors alone.

[Davey]

It may not be a high-pass filter...per se.  It's not uncommon to see a highish value resistor to ground on the output of a source component to bleed stray voltages when nothing is connected.

If the resistor in question is in series with the output (and a lower value) then its purpose is a "built-out" which serves to decouple capacitive loads and also prevents direct shorting of the device outputs should a user be fiddling with interconnect cables with power on.

In any case.....I wouldn't mess with any of the components unless you have a full understanding of their purpose.

Cheers,

Dave.