Aiyima TPA3255 Amplifier Question

[Derekinla]

Newbie here looking for info. I have a 24v 5A power supply adapter lying around. Could I use this with the Aiyima A07 or the other AIYIMA TPA3255 amp with Bluetooth and the PCM5102 DAC? There is also a third Aiyima iteration with Bluetooth 5.0 and APTX (but without the PCM5102 chip) which I presume is not as good as the one with the DAC - but not sure? I haven’t purchased the amp yet but wanted to know options. I will be using the amp near field with 4-8 ohm bookshelf speakers rated at 75 watts. The Bluetooth versions with APTX and DAC chip seems intriguing to wirelessly connect with MacBook Pro. The specs for needed power supply vary from one source to another. The Texas Instruments data sheet for the TPA3255 shows wide range of operating voltage. I’m guessing it will work? Is it bad if the voltage or amperage is too low? Also is there a difference getting the amp from the Aiyima store on EBay Vs AliExpress? Thanks!

 

[somebodyelse]

There are some useful comments from Aiyima owners in another thread, including some of the things to watch out for when buying:
https://www.audiosciencereview.com/...tpa3255-amp-do-you-recommend.9148/post-462929

Your 24V supply should work, but will limit the output power - see the TPA3255 datasheet for the graphs of output power vs. supply voltage for different speaker impedances. Whether it is limited by voltage or current depends on the impedance of the speakers - power = voltage x current, and voltage = current x impedance. You can do a first approximation by looking at the power vs. supply voltage graph and checking whether the supply can provide enough current to meet that power - which graph you use depends on how much distortion you're willing to accept, and may alter the conclusion. Taking the 10% distortion graph as an example we have 40W per channel into 8R, and ~75W per channel into 4R, so a total power of 80W and 150W respectively. That would require 3.33A and 6.25A, while the power supply has a limit of 5A, so with an 8R speaker you're limited by supply voltage, but with 4R you're limited by supply current. It's not a perfect calculation, but it'll put you in the ballpark.

If you've decided that that's the amp for you then give it a try with the power supply you already have. If it won't go loud enough then you can get a bigger power supply.

 

[Derekinla]

There are some useful comments from Aiyima owners in another thread, including some of the things to watch out for when buying:
https://www.audiosciencereview.com/...tpa3255-amp-do-you-recommend.9148/post-462929

Your 24V supply should work, but will limit the output power - see the TPA3255 datasheet for the graphs of output power vs. supply voltage for different speaker impedances. Whether it is limited by voltage or current depends on the impedance of the speakers - power = voltage x current, and voltage = current x impedance. You can do a first approximation by looking at the power vs. supply voltage graph and checking whether the supply can provide enough current to meet that power - which graph you use depends on how much distortion you're willing to accept, and may alter the conclusion. Taking the 10% distortion graph as an example we have 40W per channel into 8R, and ~75W per channel into 4R, so a total power of 80W and 150W respectively. That would require 3.33A and 6.25A, while the power supply has a limit of 5A, so with an 8R speaker you're limited by supply voltage, but with 4R you're limited by supply current. It's not a perfect calculation, but it'll put you in the ballpark.

If you've decided that that's the amp for you then give it a try with the power supply you already have. If it won't go loud enough then you can get a bigger power supply.

Thanks for the information! When I look at the power vs supply voltage graph(s) on the data sheet, they provide 3 configurations: BTL, SE, PBTL. Which one would be applicable to the scenario of using the mini amp to drive a pair of bookshelf speakers? Also in terms of THD, is 10% vs 1% a function of volume?

 

[somebodyelse]

The 2 channel amps use the BTL configuration. SE would be 4 channel, and PBTL mono. As you turn the volume up with a given power supply voltage the distortion increases - see the graphs of THD+N vs. output power in the datasheet. They're shown for higher supply voltages, but the shape will be similar for a 24V supply.

 

[Derekinla]

Am I correct in assuming that in the average real world listening scenario, most people would be listening to audio / music at much <<10% THD and that <1% THD would be reasonable # to model amp demands? Or is it fairly common for people to rock out to music with THD approaching 10% or say with movie effects in a home theater?

 

[tomtoo]

Use your powersupply first. It should make 2*25w under 1% thd . In your descriped nearfield scenario thats not bad.10%THD you will hear. 1% is not easy to hear. With that amount of Power you cant rock the house, but it gets loud for normal listening and still is relativ clean.