Gen1 xpa3 discharge noise

[quamman]

I recently got a gen1 xpa3 second hand and on ch 1 about 40-45 seconds after the amp is turned completely off ch1 will give a pop or like a record scratch noise out of it through the speaker . I have swapped speakers and does the same even if no source is connected to either rca or xlr . I am currently using xlr , ch2 and ch3 do not do this . I have spoke with service and was told this is nothing to worry about as this is the differential amp leaking power into a different ch as it powers down , even at about 45 seconds after ? I initially thought it sounds like a cap discharge. Has anyone else experience this same issue ? Thanks , Scott

[KeithL]

On most of our amps, including the XPA-3, the output of the amplifier remains physically connected to the speakers when you turn off the amp.
When you turn off the amplifier, the voltage in the power supply drains gradually, and may take as long as a minute or two to drain completely.
As the power supply voltage drops, the amplifier circuitry maintains control, so the output remains at or near 0 VDC.

However, while the amplifier is in the process of shutting down, it is still somewhat "alive".
This means that, if your preamp were to send a signal to the amplifier, it would be heard from the speaker.
It also means that, in some cases, you may hear slightly unusual noises from one or more channels as the amplifier shuts down.

You are in fact hearing the amplifier continue to operate as the last small remaining bit of power drains from the power supply capacitors.
It is perfectly normal... and no cause for concern (slight variations in parts determine which amplifier channels actually do it).
(And, yes, it is normal for this to occur for as long as a minute after you flip the switch.)

Mar 26, 2018 9:24:03 GMT -5 quamman said:

I recently got a gen1 xpa3 second hand and on ch 1 about 40-45 seconds after the amp is turned completely off ch1 will give a pop or like a record scratch noise out of it through the speaker . I have swapped speakers and does the same even if no source is connected to either rca or xlr . I am currently using xlr , ch2 and ch3 do not do this . I have spoke with service and was told this is nothing to worry about as this is the differential amp leaking power into a different ch as it powers down , even at about 45 seconds after ? I initially thought it sounds like a cap discharge. Has anyone else experience this same issue ? Thanks , Scott

[quamman]

Ok , thank you Kieth . The amp works flawlessly accept for that noise which had me worried. The seller was ready to refund me as he was never aware of it happening since he listened to it sparingly. I can let him know we are good . Thanks again, Scott

[quamman]

THe only thing that really confused me as it was still doing it even without any rca or xlr connected to it when it makes the noise . I appreciate the quick response though. I have received good support so far for all my service questions and needs in the past . A pro active and friendly service based company is no doubt appealing to anyone looking to invest in a company and its products.

[KeithL]

What you're actually hearing is analogous to the slight brief coughing noise your car might make after you turn off the ignition.
(It's a slight bleed-through of the noise the amplifier circuitry makes as "it rides the power supply rails down to zero".)

Mar 26, 2018 11:23:05 GMT -5 quamman said:

THe only thing that really confused me as it was still doing it even without any rca or xlr connected to it when it makes the noise . I appreciate the quick response though. I have received good support so far for all my service questions and needs in the past . A pro active and friendly service based company is no doubt appealing to anyone looking to invest in a company and its products.