Balanced output has white noise output?


#1

I did a search and did not find anyone complaining about noise from the XLR outputs.

I just did two things in my system and notice a low level white noise output when using the balance output from the DirectStream DAC to my Plinius SA100MKII amp

  1. Upgraded from PWD MKII to DirectStream using kit

  2. Bought and installed Audioquest Columbia 2 meter XLR cables between the DirectStream DAC and Plinius amp. I switch to using a Marsh A400 amp and notice the same faint white noise.

I can hear faint white noise coming from both speakers when I am seated 10 feet away, enough to bug me that I don’t think it should be correct design intention. It is not a hum, but faint white noise. When I use 2 or 3 meter RCA cables, it is very quiet even when I put my ears next to the tweeter and midrange. This leads me to believe the cable is fine. In fact, I tried two sets of Audioquest Columbia XLRs with the same effect.

I connect a Sony 5400 SACD player using the XLR cable directly to the Plinius amp and do not the faint white noise. This leads me to believe it is the DirectStream that is the source of the noise. Music plays fine, but essentially the noise floor of the DAC seems very high when using the XLR connection.

My equipment is plugged into PS Audio P10 conditioner.

Unfortunately, I did not bother to try the XLR connection when I had the PWD MKII before upgrading the boards to DirectStream. I bought the cables and DirectStream kit at the same time thinking I would finally take advantage of using an XLR connection.

Maybe there is an issue with the balanced output circuit on my upgrade kit? Even if I connect only the left XLR or the right XLR, I would hear noise on the speaker that the XLR cable was connected so it doesn’t seem to be a ground loop (otherwise I would hear hum)

BTW, a cheater plug on AC cable to the Directstream DAC does not affect the noise.

Did I about cover the relevant experiments? Thinking about calling in the issue to PS Audio, but wanted to see if anyone had such an experience to know if it is just my unit. Thanks.


#2

When you activate the 20dB pad (filter button on remote), does the noise go away?


#3

“When you activate the 20dB pad (filter button on remote), does the noise go away?”

Yes, the noise is greatly reduced, but then again so is the volume capability of the DirectStream DAC (20 dB I suppose). Is this an indicate the noise is coming from certain stage of the circuit and would this be considered a defect?


#4

One bit DSD DACs inherently have more noise than, say, PCM DACs, but I’ve not heard of a difference between balanced and unbalanced with respect to the noise level. There isn’t a balanced output circuit per se. The output is a center tapped transformer and the balanced is connected across the whole winding and the unbalanced is connected across 1/2 the winding. The internals of the DS are balanced thru out.

The 20dB attenuator is analog so it lowers the noise and the output level identically, if you never feel a need to turn the DS volume above 60 you should use the 20dB attenuator and use a higher volume setting.

When the 20dB attenuator is engaged the DS’s volume level goes to 106 instead of just 100, this little extra makes the difference for some people. If you are close to the maximum level that you need when using the 20dB attenuator and didn’t try turning the level up above 100, you might try it again.


#5

Ted,

Thanks for your useful comments. I will try this tonight to see if I can still have sufficient gain for my system using the 20dB pad.


#6

And just so’s ya know, in the 20dB attenuated mode DirectStream can go higher than 100 on the volume.