Audio POP when starting up and shutting down the radio

  • 1
  • Problem
  • Updated 4 years ago
  • Not a Problem
When I start up or shut down the radio (i.e. press the power button), there is a pop from the speakers.  The "start up"  pop is low, the "shut down" pop is fairly loud.  Its been doing this all along so it is not firmware/software related.  Based on some feedback it seems like this affects a number of folks but hasn't been reported previously as far as I can tell. 

- Radio is a 6700 (others have also reported this on the 6300 and 6500)
- Audio Engine 5+ powered speakers
- tried a set of Sony powered speakers, same thing
- been reported by others using different speakers (Bose, etc) 
- my typical audio settings are shown in the snapshot below. 
- tried different settings of SSDR master and slice audio settings and the speaker volume setting, no difference
- My shutdown procedure is to stop SSDR first and then press the power button on the radio.  The pop occurs after the "shutdown" message is displayed on the radio.   After the radio is shut down, I remove the DC power and get the usual "low voltage" message a few seconds later.
- muting the sound in SSDR before shutting down has no effect. 
- there is a very slight pop from the headphones also but its hardly noticeable compared to the pop from the speakers

This is a pretty minor issue and depending on the solution FRS may decide it doesn't warrant a very high priority or even fixing. It's one of those "fit and finish" kind of things.  If you drive a luxury car, you don't expect the door to squeak when you shut it.   Doesn't really affect the performance of the car but may affect your perception.  It certainly shouldn't bump any of the more important fixes and enhancements.

Thinking out loud here.   I wonder if the supervisory processor (that is running in the radio anytime there is power applied),  could mute the speaker on startup until the radio is online and also mute it when you push the power button to shut it down.  Its always easier if the solution is software rather than requiring a hardware fix. 

FRS team -- Do you see this in the test lab or your personal radios also?
Any user side solutions?

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com

***** slice volume varies, just an example below ****

Photo of Al / NN4ZZ

Al / NN4ZZ

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Posted 4 years ago

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Gerald - K5SDR, Employee

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Official Response
Al, this is normal.  It is the result of charging or discharging AC coupling capacitors in the audio circuit when you turn power on or off.