Random blast of 0db white noise.

System is in my office with two Jamo bookshelf speakers, a Klipsch 10" Sub, an old Denon 3802  that has never given me a lick of problem in all the years I used it in the theater room.  Also, an IBM i5 Thinkcenter PC, a Parasound ZDAC, a Parasound ZPhono and a VPI Super Scoutmaster.

Anyway, running JRiver 21 with a few TB of discs I've ripped or downloaded HD FLAC files.  Sounds pretty damn good for being a bunch of second use gear, but occasionally I'll be listening to music or a podcast and I'll get a blast of white noise (could be pink, but I haven't RTA'd it :)), and I have to hit the mute button on the keyboard.  It killed the tweeters on a set of KEF iQ10's, but so far the Jamo's are holding up.  I keep the volume on the Denon at -10 and then control the volume from the keyboard or via whatever player I'm using.  I've never run into anything like this before, and as you can imagine, it's a bit unnerving when it starts blasting.

My gut tells me it's the DAC or the PC, as it happens with different software, and I don't think there is anything wrong with the Denon, and it's old enough to have a minimum of DSP onboard, ie; no Audyssey or such.


Full range digital noise is like this, so maybe don't do that. :)

Use the Denon as your volume control if you can.

What is happening most likely is that for some reason your DAC is loosing the lock on the digital signal. Could be a bad connection, or some software/PC glitch.

When this happens your DAC is now outputting full range noise.

I'd suggest try a new (cheap) cable and use the Denon as volume control for a little while.
Thx Erik.  I am using AQ cables, and recently moved USB ports on the computer and haven't had this problem since...but we'll see.

Why would a DAC output an analog signal when losing lock?

Why would a DAC output an analog signal when losing lock?

Because the DAC gets confused about where to start reading music within the data stream.

Think of the data not as music, but packets, or envelopes. Each packet has more data than just music in it. In order to read a packet correctly you have to get the start of it right. If you start reading the packet in the middle, you misinterpret the entire packet.
For whatever reason, the DAC does not realize it is confused.

An easy way to try this is to feed a 2 channel DAC 5.1 from a HT source. It does not interpret any of the 5.1 data correctly so noise is all you get.


OK copy that.

Since switching to a different USB port on the computer, I haven't had this issue, so that's what I'm thinking the issue is.  I've used Cambridge, Audio Quest, ART, and CEntrantrance DACs and this Parasound in various systems up to and including a theater PA without this issue, so I know this is not very scientific, but it seems to me the computer is the lone variable.

Thanks again.

Update, (if anyone cares)...I'm sending the ZDAC back to Parasound as the same issue was continuing to happen.  I 'm using my CEntrance DACPort LX without issue, and may even like the sound a bit better.
ZDAC is back from Parasound.  Repaired, (said replaced 5v power supply), and have no problems in the week it's been back in use.