SMSL AO300 clicks/resets due to headphones esd while petting cat, wearing socks, etc.

[Subwoofer2596]

While wearing headphones, I can reliably force a clicking noise, which is caused by the AO300 unit itself seeming to temporarily reset. The sound will cut out and the LCD will display "DoP 2.8224 MHz" for about 1 full second before the unit switches back to the previous output settings and plays properly. This happens regardless of input interface used. Whenever I generate enough ESD while wearing headphones, this click and reset happens. It happens every single time I pet my cat sitting on my desk or if I intentionally rub my feet on the carpet while wearing socks. Obviously I'm trying not to do this, but it unintentionally happens often enough that it is really souring what is an otherwise very positive experience with the SMSL AO300. Is this a faulty unit? Shouldn't simple ESD be directed to the metal casing rather than the internal PCB?

 

[Dunring]

It's a bad unit and likely the ground isn't connected. I had one a little while to test for function and didn't notice anything like that. They have a 3 prong power cord and touching the case shouldn't be doing that.

 

[Subwoofer2596]

Thanks! The fact there is a 3 prong connector is strange to me because there's a photo on the web of the internals and if you look closely, the ground prong isn't even connected to the PCB. Could that be the issue? I've reached out to the seller and I'll update this thread when they contact me back.

 

[Reji]

I have the same issue - are you using 6.3mm or 4.4mm jack?

 

[Subwoofer2596]

I have the same issue - are you using 6.3mm or 4.4mm jack?

I am using the 6.3 mm jack. I have not tried the 4.4 mm one. I have the unit with silver faceplate. I was contemplating returning for the all black unit to see if that’s any different. But I suspect this is a design flaw that will require a redesign of the headphone circuitry to have more ESD protection.

 

[Reji]

I am using the 6.3 mm jack. I have not tried the 4.4 mm one. I have the unit with silver faceplate. I was contemplating returning for the all black unit to see if that’s any different. But I suspect this is a design flaw that will require a redesign of the headphone circuitry to have more ESD protection.

My unit is black and i am using 6.3mm aswell. Maybe 4.4 has more protection on circuit

 

[Subwoofer2596]

My unit is black and i am using 6.3mm aswell. Maybe 4.4 has more protection on circuit

Perhaps, but I doubt it based on the photos above. The 4.4 mm jack is on a daughter card that piggybacks off the same connections as the 6.3 mm jack. It's really frustrating as the amount of electrostatic discharge that can cause this issue is miniscule. You literally don't feel a shock. It just feels like SMSL cheaped out on some components needed to handle this or they just didn't take ESD into account when designing the jack. With the exact same setup but my headphones plugged directly into my Apple MacBook Pro, I don't get these clicks and pops.

This thread on the SMSL C200 seems to be a related issue and while SMSL claimed a firmware update resolved the issue, other posters chimed in to say it didn't help them. The thread has since gone dead.