ProtoDAC TDA1387 X8 project

[hifinet]

Ive had my kit built for a while now and I am satisfied with how it sounds. 
I am wondering if anyone else has noticed a very faint pulse from thiers tho?
 
I noticed it when i had audio paused but my amp volume was up.
The woofers had a pattern every second or so that would repeat and looked like a 1-2hz pulse. I connected the protodac to a scope and seen about a 30mv wakky pattern.
Its also reproducible with a song that starts very quiet, and you turn up the amp loud, you can see the speakers fluf in and out every second or so.

Its extreamly quiet! Under normal listening, I would have never heard it. The woofer fluf is visible but not audible, but there is an audio portion to this pattern that can be heard when the volume is up with nothing being played.

Anyways, thanks to all for the great sounding dac, and if there is a fix for this, i look forward to it, and if not, no worries. 

Thanks.

Are you using ethernet or WiFi? With some of the prototypes built on perf board, WiFi was picked up. Nothing playing it is a periodic noise. With a file playing there is a more of a continuous,  pulsing noise. The PCB has a ground plane, and I have not heard it with the PCB. There also might be a bad solder joint that could act as a diode, and pick up RF.