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Any way to prevent pops on power up and down with Fosi Audio BT20A-S?

cinemakinoeye

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Nov 28, 2021
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Location
Newtonville, Massachusettes
I have a Fosi Audio BT20A-S that I need to be able to power on and off at the wall connection. But there is a nasty pop (probably not good for my tweeters) upon power up and power down. I am well aware I can leave it on all of the time or use the front switch, but those are not viable options for my use case. And alternatives to prevent this problem? Some form of delay switch perhaps?
 
That's generally basic to the design, sorry. Some amps like my A21 have an output relay which only closes when the output stabilizes.
 
Step 1; Turn off the unit
Step 2: Turn off the power supply brick (at the wall outlet)

If you do Step 2 only, then the unit is powered up even while the power brick capacitors are discharging - which will cause the pop... of course. This is not supposed to happen and can damage the amp/speakers.
 
It's not all that uncommon to have turn-on or more likely turn-off pops.
In the pro world the rule is.

Turn-on order:
1] sources
2] control units
3] power amplifiers

Turn-off order:
1] power amplifiers
2] control units
3] sources
 
I have an old Acurus A250 that will keep playing for a while (like 30 seconds or more if at low volume) after flipping the power switch as its big power capacitors drain.

No pops on start or stop, just gets a little crackly at the very end of power off.

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When you want a solution: Buy another amp with a proper output relay or add a loudspeaker switch.




Turn-on order:
1] electronics
2] speaker switch

Turn-off order:
1] speaker switch
2] electronics
 
Last edited:
I don't have any with my Bt20A with a any power supply, im using a 24v,10a psu

Which mini class d amps dont' have it ?
 
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