Topping PA3s Review (Desktop Amplifier)

[racingpht]

For anyone who's curious, I recorded some strange noise made by my PA3s. In the video I was playing a 60hz sine wave, the amp generates some noise at certain volume. If you pay attention you will notice that triggering the noise on/off are at slightly different volumes, as if the amp is transitioning into and out of different "states" with a threshold of a few dbs.

Very funny, I wonder if that's the "smart" features mentioned in MA12070 white paper.. such as "The power management algorithm dynamically adjusts switching frequency and modulation to optimize power loss and EMI across the output power range."

But I never noticed the same problem on my MX3s which also uses MA12070.

BTW: The extra noise are in -80db range compared to the 60hz signal. Regular measurements might say it's inaudible. This is a nice example that something might measures fine but you can easily hear something wrong Speaker driver distortion here is -20db but still sounds perfectly fine which is also kind of shocking.

 

[racingpht]

For anyone who's curious, I recorded some strange noise made by my PA3s. In the video I was playing a 60hz sine wave, the amp generates some noise at certain volume. If you pay attention you will notice that triggering the noise on/off are at slightly different volumes, as if the amp is transitioning into and out of different "states" with a threshold of a few dbs.

Very funny, I wonder if that's the "smart" features mentioned in MA12070 white paper.. such as "The power management algorithm dynamically adjusts switching frequency and modulation to optimize power loss and EMI across the output power range."

But I never noticed the same problem on my MX3s which also uses MA12070.

BTW: The extra noise are in -80db range compared to the 60hz signal. Regular measurements might say it's inaudible. This is a nice example that something might measures fine but you can easily hear something wrong Speaker driver distortion here is -20db but still sounds perfectly fine which is also kind of shocking.

Since I can't edit my post anymore, I want to add a bit more information(probably as someone else already mentioned):

The strange noise is gone when driving with XLR input in the same test environment.

So this amp has a pretty noisy RCA input. The filterless design seems not the one to be blamed. You should always use XLR input with this amp. minidsp2x4 or 2x4HD is not the a good pair for this amp but on PA5 everything seems fine.

 

[Solveit]

Since I can't edit my post anymore, I want to add a bit more information(probably as someone else already mentioned):

The strange noise is gone when driving with XLR input in the same test environment.

So this amp has a pretty noisy RCA input. The filterless design seems not the one to be blamed. You should always use XLR input with this amp. minidsp2x4 or 2x4HD is not the a good pair for this amp but on PA5 everything seems fine.

Yes RCA input suck, MA12070 chips sounds best with differential input.
And it's an very nice chip if you run with an cheap DAC like SMSL m300 se.