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AIYIMA A05 Review (Budget Amplifier)

DualTriode

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Hello All,

These little amplifiers with separate power supplies make possible and necessary to take a closer look at the assortment of possible power supplies.

Possible are transformer, full bridge & half bridge with CRL or CRC filtering with and without regulation. High frequency switching, and batteries. Most of the MeanWell type switching supplies come with Power Factor Correction, meaning active controls to reduce powerline harmonics, you know 120hZ 180Hz kind of distortions, not a bad thing to reduce for audio amplifiers. Not to leave out the 50hZ gang 100, 150 200hZ and up the line.

Thanks DT
 

restorer-john

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Hello All,

These little amplifiers with separate power supplies make possible and necessary to take a closer look at the assortment of possible power supplies.

Possible are transformer, full bridge & half bridge with CRL or CRC filtering with and without regulation. High frequency switching, and batteries. Most of the MeanWell type switching supplies come with Power Factor Correction, meaning active controls to reduce powerline harmonics, you know 120hZ 180Hz kind of distortions, not a bad thing to reduce for audio amplifiers. Not to leave out the 50hZ gang 100, 150 200hZ and up the line.

Thanks DT

This amplifier is being run at the Vmax for the chip. It's rated up to 30V with an absolute maximum of 32V and the SMPS supplied has a [email protected] rating. So we know there's not enough current for full power out of both channels even with the high efficiency of these Class D BTL amps.

We also don't know how well regulated the supplied SMPS is. Usually the cheap Chinese SMPSs are pretty average and will dip in voltage near full rated current, if they make it at all. And with autoswitching (120-240V) SMPSs, they tend to regulate better on 220-240V as opposed to 120V, IME.

More investigation is needed for sure, as I often think these little amplifiers are constrained by the power supplies they ship in the box. A big variable 10A DC supply with current monitoring would answer this. I also have significant doubts as to the ability of 2.5mm coaxial DC power jacks, cable and connnectors along with the PCB track designs for handling the current, especially as the rated power of these things gets up above 50W or so. Voltage drops are significant.
 

ben2talk

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The not so good things:
Poor frequency response at 5W resistive.
Severe load dependent response deviations.
Inability to even come close to rated power specifications.
Premature shutdown into 4R.
Faulty tone controls.

:)

Right now I'm surviving with a ZK-MT21 - originally purchased (for 425 THB which is around THB 432.64 ( THB 432.64 ( $13 ))US). I bought it for the subwoofer which it drives very nicely and since my Yamaha Receiver kicked the bucket last week, driving my Monitor fronts (6 ohms, 90dbW) as well - with relative ease.

So I'm doing a lot of surveying now, as to my upgrade paths. Certainly getting rid of the AUX from the computer would be good - a USB DAC perhaps - but I'm also sold on BT. If I turn on the laptop, it can patch in. I can put a bedtime story on my phone - BT is definitely awesome (sorry - the A07 is just a toy without it :)
the small weight and size is more a trouble than advantage. The unit travels on the surface rather than sitting firmly.
Sorry - that's not true. I fixed my tiny MT21 amplifier to the table under the TV with some nano tape because it was lighter than the cables attached to it.
It's almost invisible, except for that LED.

As far as power goes - I think conservative is best. Keep the volume turned down - works with most amplifiers ;) Remember it takes 300W to double the volume of 30W and for most purposes, a good clean 20W is tasty enough.
 

amanieux

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it does not measure as well as a07 but can we hear the difference at low volume, near field destop setup casual listening? thanks
 

amanieux

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I got it!

A05 = ~-50dB distortion
A07 = ~-70dB distortion :D

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is this 20db distortion difference audible at casual low volume listening in a near field desktop setup ? thanks
 

amanieux

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This is one of the reasons why I call this and similar amps a toy. One cannot even connect any reliable banana speaker connectors to their output. Also the small weight and size is more a trouble than advantage. The unit travels on the surface rather than sitting firmly.
I understand some love it for the budget price. But I hope this forum is more than to adore super low prices of the consume electronics. It is about parameters and design and built quality so the issues are to be named clearly.
the point of the small size is that we can glue it at the back of speakers and remove the clutter on the desk (volume controled at the digital source)
 

respice finem

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This amplifier is being run at the Vmax for the chip. It's rated up to 30V with an absolute maximum of 32V and the SMPS supplied has a [email protected] rating. So we know there's not enough current for full power out of both channels even with the high efficiency of these Class D BTL amps.

We also don't know how well regulated the supplied SMPS is. Usually the cheap Chinese SMPSs are pretty average and will dip in voltage near full rated current, if they make it at all. And with autoswitching (120-240V) SMPSs, they tend to regulate better on 220-240V as opposed to 120V, IME.

More investigation is needed for sure, as I often think these little amplifiers are constrained by the power supplies they ship in the box. A big variable 10A DC supply with current monitoring would answer this. I also have significant doubts as to the ability of 2.5mm coaxial DC power jacks, cable and connnectors along with the PCB track designs for handling the current, especially as the rated power of these things gets up above 50W or so. Voltage drops are significant.
This, and, if such a power supply will work close to its maximum power, it's "designed to fail". With this amp, this is not necessarily the case, because most are likely to end up in low-power setups and not driving big and "power hungry" speakers, but still, PSUs should be sufficient for the stuff they will be powering. For many years, the PC market suffered from the same "misery".
 

whazzup

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is this 20db distortion difference audible at casual low volume listening in a near field desktop setup ? thanks

Just to clarify, I was just joking when I referenced their names to their measured distortion levels....
As for your question, I did do something similar on my desktop setup (not Aiyima), when I was adjusting the Peace EQ software.
I was trying to mute my bass channel, but noticed that Peace's default minimum pre-amp value of -30dB was still too high and I could still hear sounds coming from the subwoofer. I had to reduce the minimum to -60dB (in Peace's settings) to make it truly inaudible. So, -50dB should be sufficiently low for most people, but as always, YMMY.
 
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