Why do we hear a "click" sound when powering on or muting speakers?

1) Why we turn on the power of speaker, we may listen a sound like opening a
can of cola?
2) The same problem appears in the mute, why?

3) What does "soft mute" mean?

Thanks,

Re: An audio problem

On power on all capacitors are charged and therefore the output of the power stage generates huge surge, which goes straight to speakers and you hear this surge as loud "click".
"MUTE" function is performed within pre-amplifier and that is the reason you will hear this "CLICK" with mute on and off.
Some amplifiers use "power-on" deley relays to protect speakers and power amplifier. This means that the speakers are conected to the output of the power stage after seconds .. when the amplifier achieves stabile state ..

"soft mute” = ramping the volume down/up to mute/100%

Regards,
IanP

Re: An audio problem

IanP said:

On power on all capacitors are charged and therefore the output of the power stage generates huge surge, which goes straight to speakers and you hear this surge as loud "click".
"MUTE" function is performed within pre-amplifier and that is the reason you will hear this "CLICK" with mute on and off.
Some amplifiers use "power-on" deley relays to protect speakers and power amplifier. This means that the speakers are conected to the output of the power stage after seconds .. when the amplifier achieves stabile state ..

"soft mute” = ramping the volume down/up to mute/100%

Regards,
IanP

Click to expand...

I can't uderstand what is mute/100%? Does it mean the attenuation of sound is
not so much as full mute?
What's the time requirement for rampin up or down in genreal speaking?

Thanks,

Re: An audio problem

mute = mute
100% = full level

I am not aware of any time requirments or rules ..
In some systems (aircraf: pilot addressing passengers) ramping down occurs almost intantly (<0.5s), but ramping up takes a few seconds ..

Regards,
IanP

An audio problem

I think this maybe abrupt current comes quickly.

Re: An audio problem

usualy manufacturers of cheep grotty design hifi junk plastic rubbish

use transistors to 'mute' the inputs to either the preamp or power amp sections of a hifi or to both!!!!

you said you get the same effect from the mute button being used


somthing all the reply's didnt cover

sounds to me like stray capacistance within the mute circuit


//
soft mute is an effected decrease in volume amplification when a high level like a current surge caused by say a switch changing in your house like the fridge switching on
and is addative rejection technique ... original signal is feed to the same signal that is phase shifted by 180 degrees hence it cancels it out the signal path the rubbish
sometimes a processor is used to decide what gets sent back
usualy its just two filters that are tuned to reject some types of noise like a scratch in a record wow and flutter etc from motional feedback systems
there are as many systems as metal detector types
//



the main question you asked is why
1} you get a klink when you switch the hifi on
2} you get the same effector when the mute is switched


the answer is one of a fault in the mute circuit

as i say it sounds like a small value cap that has dried up
this would cause the transistor switches time vectors to change
and as the mute section can be common to both switch on and press mute
they will have a common klick sound

look for 1uf - 10uf types in the mute section of the audio amp

chances are the mute is in the power amp section of the system you have

my advice is first to get the schematic

then see where the mute section lives

then change the associated caps {electrolytic types}
and check all the resistors {as a damaged resistor or tracking...
{cracked or chipped or dry joints}}
can give the same fault common to both channels if it is stereo}

Re: An audio problem

Hello,

But even the mute function is enabled, pop-sound can still be heard when powering-up or down. Is there any way to remove this pop sound? Any recommendation or schematics/circuits to tackle this problem. Thx in advance.

Re: An audio problem

One possibility is the output voltage of the final stage goes from zero to the final value as the power supply voltages go from zero to their final values. The more expensive amplifiers have a relay between the output stage and the speakers. There is a time delay before the relay closes.

The simplest solution for you if this is the case os to have a manual switch between the speakers and the amplifier to do this same function.

If your amplifier has a single polarity power supply there will be a series capacitor to the speakers that will need to be charged. You can put a 100 ohm resistor across the speaker leads prior to the switch to carry the charging current.

Re: An audio problem

Thx flatulent,
Your suggestion of "manual switch" is not possible in my case because there is no switch available in the design.

Yes, the requirement of the circuit are both single-ended (that needs large output capacitor for ac coupling to the speaker) and BTL configuration (similar to LM4863)
Could you kindly let me know the exact schematics of connecting 100Ω resistor?
Or is there any other way available to electronic control of switches or any circuit technique to remove pop sound?

Thx in advance for any suggestion.

Re: An audio problem

If you can put your circuitry inside the amplifier box, you can use a 555 timer to make the time delay for the relay closing. For the resistor, just put it from the capacitor output to ground.

Re: An audio problem

Thx so much, flatulent.

After I can put 555 timer, what circuit should I add to remove the pop sound? Or any switches or where the switches are located or any other special circuits?

Any comments/suggestions are highly welcomed.
Thanks in advance for your reply.

Re: An audio problem

Another arrangement is to drive the relay coil with a FET. Have the gate go to a large capacitor to ground and also a large resistor to the supply voltage. That way there will be a time delay before the FET turns on and closes the relay. Have the relay contacts in series between the speaker and the audio output capacitor. You should put a diode across the resistor pointing from the capacitor to the supply so that the time delay capacitor can quickly discharge when the power is turned off.

Another approach is to slow the supply ramp up so that the output transient is below the human hearing frequency range. Try thermal inrush current limiters. These are plastic material which has a high resistance at room temperature and reduces with higher temperature. Keystone was a common brand many years ago.

Re: An audio problem

Thx so much, flatulent.
Your valuable advices helps me a lot.
Could you kindly provide some suggestions/advices on the present following situation?

However, the physical size of the relay is too large to install on my limited PCB area. Would the semiconductor switches replace this relay? But the semiconductor switches 74LVC1G384 turn-on resistance is 6.5Ω at Vdd=3.3V in my case. This is too large for my 8Ω single-ended configuration driving case. And the worst is that the pop sound can still be heard even I use MΩ order resistor and 1uF capacitor connecting the control terminal of the semiconductor switch. Similar plastic thermal inrush current limiter physical size is too large to build on my PCB.
So is there any way(semiconductor switches/IC or any circuit) to remove pop during powering up/down?

Also the series 100Ω resistor severely limited the output power that could not be accepted in my case.
Thx so much in advance for your valuable advices.
Any comments/advices are highly welcomed to all readers.