I recently bought one of your 9018 USB DACs (model 10000146).
I'm using MacOS, connected to headphones.
The Midi app on MacOS is set to drive the DAC at 48K, 24bit, but I get popping sounds every 5-10 seconds... not corresponding to any events that I can tell (like volume changes, song pauses, etc.)
It's possible that my headphones are very sensitive, and therefore any pop is audible; I have to turn the volume down to -41dB in order to tolerate listening; this is kindof a drag, but I knew going in that the unit put out lots of power and that my headphones were sensitive (B&O H6).
How can I go about finding the cause of the pops and eradicating them?
Have you tried to reboot the computer, and connect to another USB port? After connecting then wait 10 seconds before starting to play music.
What is the player you use, have you tried other, any difference?
It shouldn't be a audible pop even with very sensitive headphones.
Of course I tried rebooting; and yes, multiple ports.
After some trial and error, it seems to be related to Chrome; it happens even when no player apps are loaded, and no tabs are playing sounds...
But it seems like maybe that Chrome is accessing the sound card? On a more normal volume situation, it wouldn't be audible I suppose... but since one has to listen at only 4-5% volume, it's quite a pop.
Does this help? Obviously, it's not HiFiMeDIY's fault, but I'd appreciate help in tracking it down.
Does it stop if you reboot and start Chrome with only 1 tab open?
No, it doesn't stop; I've done some experiments, here's what I've discovered.
With ONE tab open in Chrome after a fresh reboot, I'll make some sound, say YouTube... I'll pause the video, and wait, and precisely 10s after pausing, there is an audible POP. I've been able to repeat this consistently. I've also been able to prove that it is NOT flash, which I have prevented from running on ANY website.
So it seems to be Chrome closing the audio device... it doesn't pop when it opens though.
I tried the same thing on Safari, which presumably would be more well-integrated into the OS, and found similar results: a pop about 10s after a sound stream stops.
Then I tried a player app; in my case, VOX; same thing, except it closes sooner; just a second or two. An interesting point about VOX is that it claims to be accessing the USB device directly, the HiFiMe DAC is not set to system default, and VOX is trying to sync same rate with the player (in this case, a 48K encoded track).
I opened up the console app and have this:
3/23/17 4:22:39.099 PM VOX: Hogging to audio device: HIFIME SABRE 9018
3/23/17 4:22:46.996 PM VOX: Unhogging audio device: HIFIME SABRE 9018
I don't see any audio-related messages from the browsers.
I've been able to duplicate this effect with a "quick look" from Finder on an audio file too.
I've tried all of this with the USB dac plugged DIRECTLY into each of the USB ports on my MacBookPro, and via a hub.
SO, it's clearly not my software. At this point I am confident in saying that ANYTHING that sends any audio to the DAC on the mac will result in an audible pop some seconds later.
Some more interesting evidence here.
In a shell on MacOS, try this:
while true; do sleep 0.5; say -a 60 ' '; done;
This will cause the built-in speech synthesis to say " " every half second; (the -a 60 tells the program to send output to the USB HiFiMe). One hears a "click click click click"... changing the sleep time changes the click time.
If you lower the number of sleep enough, you can make the click go away; in my case, it was 0.3s. This kept the audio device OPEN, and using other player software didn't pop after finishing a stream.
This page helped me discover this:
This eats about 5% CPU :-( but it's a clue...
Hi again, you said initially that the pop was occurring while playing music, every 5-10 seconds, so then it couldn't be happening when the program is closing the audio device. Or was that not the case?
It's normal for a very soft pop sound when the audio device is closed, however we haven't experienced any headphones that are so sensitive so this is a real problem. What is the efficiency for your headphones ?
I did say that; at this point, after my recent trouble-shooting, I'm guessing that I was mistaken... that the pops were coming and going seemingly randomly as different browser tabs (or whatever) opened and closed the audio device, and that it is likely that I did NOT hear it during music.
It's not a "real problem" except that it's annoying. I don't think there is damage to hearing possible or anything, but it's annoying, for sure. It also doesn't seem to be solve-able, being an Apple problem.
I can't find specs on my headphones; they are these:
I found this non-authoritative source: