DAC popping noise after turning off?
Jan 10, 2017 at 6:33 PM Thread Starter Post #1 of 8

Scolopendra

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Hi there!
 
I have a computer hooked up to my DAC, preamp, amp, and speakers.  As a matter of habit, I have been deactivating my amps before deactivating the DAC.  However, today I deactivated the DAC first, and heard a popping/cracking noise coming from either the DAC, amps, or right channel speaker.  What is this noise from, and is it bad/caused damage? 
 
Thank you!
 
Jan 10, 2017 at 7:59 PM Post #2 of 8
That noise is just part of the procedure of the DAC turning off

I don't know what in specific causes this but to avoid it, you should make it a habit to always shut off what's closest to the speakers first (amps) and what's furthest from the speakers last (computer)

When turning the system on, things should go opposite. Turn on the computer first, then the DAC, and turn on the amps last.
 
Jan 10, 2017 at 9:37 PM Post #4 of 8
I really doubt anything would have been damaged by that if it was only once or twice.
 
Speakers can be damaged by clipping or loud noises repetitively but the popping (albeit unnatural for the speakers), shouldn't cause any damage, so long as you try to avoid it.
 
Jan 13, 2017 at 10:22 PM Post #7 of 8
A pop or crack on switching off is an indication of capacitors discharging.  Most likely, the DAC has a high amount of capacitance onboard.  This will cause a DC spike on turn-off, just like some amplifiers will have a DC spike on turn-on before the onboard capacitors charge up.  It's why relay-delays are incorporated in many power on/off circuits in order to minimize the spikes.
 
A good practice is not necessarily the turn-on/turn-off order, but rather - always turn the volume down on the amp before making a change.  That applies whether it's power off/power on, disconnecting or connecting sources and output devices, etc.
 
Jan 14, 2017 at 12:46 PM Post #8 of 8
I design speakers, my latest are active DSP based three way transmission lines. Damage can be done the first time it happens, so best check to hear if anything did happen. I normally leave my active crossovers on at all times to prevent the pop, they take very little power so not concerned, but as mentioned there is a proper sequence. Simply turning the volume down does not guarantee damage will not be done. If the volume control is digital or on the front end of things you risk it all.
 
Speaker drivers can be thought to be a bit more tolerant, but when using drivers like I do it does concern me and my fellow designers. Tweeters are at greatest risk with descending order top to bottom end. In my case I use AMT type tweeters that can only handle only a small fraction of the power the amp channel can produce. On the mids, mine are push pull planar magnetics and cannot be replaced, this is especially critical as they only handle 1/3 the power of the amp channel.
 
Have I oops, you betcha by golly! Happy to say no damage was done.
 
BTW I have used the planars as headphones some years back. Work very well for this task, but a bit too heavy on my noggin.
 

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