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AIYIMA A07 TPA3255 Review (Amplifier)

delta76

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AD18 has never been very highly regarded from what I've read.
Yes no recommendation from Amir. Also it was from 2019. If anything you can be sure hifi equipment from Chinese makers obsolete fast (as new versions come out like every 6m)
 

MysticWizard

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Hi Everyone,

From the original review:

Personally I would not leave these plugged in permanently if I am not around.

Now because of this statement, I would like to put this unit behind a smart switch, but I am worried that if I leave it in the ON setting and I restore power with the smart switch, it will pop my socks off :p

Can anyone with this unit ease my worries or confirm I'd have to buy extra strong elastic socks?

Thanks!
 

daftcombo

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Got an A07 yesterday as a temporary solution. Quick impressions:
  • It's tiny. The pictures really misled me: It's only about half the size of my DAC (SU-9n). About 15 x 10 x 4 cm.
  • My speaker cables are trying to pull it off the shelf :confused:
  • It looks and feels cheap. I get it, it's an amp for 80$. The volume knob is scratchy, there are some small scuffs on the housing of my unit, some of the feet fell off/didn't really stick, the 32 V PSU which came with it looks "barely trustworthy".
  • The PSU emits a faint noise around 7 kHz when plugged in, which is audible up to 0.5 m away. Not really of any concern, as it's inaudible where it usually sits (e.g. behind a shelf).
  • There's no speaker pop when turning on the amp. Was kinda impressed considering the price.
  • There's some speaker hiss. In a quiet environment, it's audible up to about 2 m with my ELACs (sensitivity 87 dB) with the volume set to 5/60 on the amp. In an unfair comparison, on a Hypex NC122MP-based amp, speaker hiss is only audible up to around 0.2 m.
  • The speaker hiss scales with the volume setting.
  • Overall, the A07 works and sounds fine. There's really nothing special about it and nothing to complain about.
  • My subjective impression is, that there's something up with the treble. Might be placebo, because I stumbled upon the measurements by @pma here, before I got the Aiyima. There seems to be a very faint lack of higher frequencies (>7 kHz). Can't really put my finger on it and it's probably imagination. I'm sorry that I can't provide any measurements for this. Nonetheless, it should be clear that this amp isn't as perfectly corrected as a Purifi unit for 20x the money.
Not sure if I'm going to keep this, even as a temp solution. Just want to get rid of that speaker hiss for now and this certainly doesn't achieve that, although it is better than my current setup. Also, the fact that I'd essentially have to glue it down to keep it in place doesn't really work in its favour ;)
I have the Aiyima A07 , I have an Hypex NC252. The latter doesn't hiss in speakers past a few centimeters, the first still hiss at 2m. Exactly the same.
 

tinnitus

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Hi Everyone,

From the original review:



Now because of this statement, I would like to put this unit behind a smart switch, but I am worried that if I leave it in the ON setting and I restore power with the smart switch, it will pop my socks off :p

Can anyone with this unit ease my worries or confirm I'd have to buy extra strong elastic socks?

Thanks!
Hi Wizard, I have two A07 which I switch on with a relais. If you switch the amp as last on there is no pop.
 

Zilo

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Advice needed,
A07 with 32v 5a power adapter connected to 3 way floorstanding Kef 103.3
Impedance: 4Ω
Sensitivity: 92dB
Recommended Amplifier: 50 to 200W

Planning to upgrade the power adapter to 350w
What will be the best combination?
24v 14.5a
32v 11a
36v 9.5a
48v 7.5a
Or lower 240w as 24v 10a?

Thanks in advance for any advice
 

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Roland68

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Advice needed,
A07 with 32v 5a power adapter connected to 3 way floorstanding Kef 103.3
Impedance: 4Ω
Sensitivity: 92dB
Recommended Amplifier: 50 to 200W

Planning to upgrade the power adapter to 350w
What will be the best combination?
24v 14.5a
32v 11a
36v 9.5a
48v 7.5a
Or lower 240w as 24v 10a?

Thanks in advance for any advice
Very simple, 36V/9.5A max. 200W, 48V/7.5A max. 180W, 48V/10A max. 300W. Each at 4 ohms.
 

delta76

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Advice needed,
A07 with 32v 5a power adapter connected to 3 way floorstanding Kef 103.3
Impedance: 4Ω
Sensitivity: 92dB
Recommended Amplifier: 50 to 200W

Planning to upgrade the power adapter to 350w
What will be the best combination?
24v 14.5a
32v 11a
36v 9.5a
48v 7.5a
Or lower 240w as 24v 10a?

Thanks in advance for any advice
With that sensivity you will likely not need more than 20wpc, so any adapter will be fine. Unless you go with very loud music (Which can be harmful to your ears)
 

dr_mick51

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With that sensivity you will likely not need more than 20wpc, so any adapter will be fine. Unless you go with very loud music (Which can be harmful to your ears)
I'd bet he does not need more than 5W/ch (being generous).
Really, what is all that need for "more power"? If people measure the voltage at the output with a multimeter, or the current at one of the wires with a clamp meter they would get "shock" by the ridiculously low amount of power needed. P = V^2/R = I^2*R = V*I
 

dr_mick51

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Advice needed,
A07 with 32v 5a power adapter connected to 3 way floorstanding Kef 103.3
Impedance: 4Ω
Sensitivity: 92dB
Recommended Amplifier: 50 to 200W

Planning to upgrade the power adapter to 350w
What will be the best combination?
24v 14.5a
32v 11a
36v 9.5a
48v 7.5a
Or lower 240w as 24v 10a?

Thanks in advance for any advice
I want you to look at the TPA3255 datasheet at figure 8:

1660311506037.png


This shows you how much power the amplifier can output at specific input voltages with THD+N of 1%.
Now, let's do the math for all the possible candidates, but first let's assume the power supply are 100% efficient(which is impossible, in reality they are 80-90% efficient) meaning that for every watt consumed from the main it produces 1watt DC.
with a 4ohm speaker:
24V 14.5A: 60W/ch, =>60W/24V=2.5A/ch=5A. We can see this power supply is not limited by current and is able to provide 60W/ch
32V 11A: 110W/ch, => 110W/32V=3.43A/ch=6.875A. Again this power supply is not limited by current and is able to provide 110W/ch
36V 9.5A: 135W/ch, => 135W/36A=3.75A/ch=7.5A. Again this power supply is not limited by current and is able to provide 135W/ch
48V 7.5A: 230W/ch, => 230W/48V=4.79A/ch=9.58A. This power supply does not provide the required current to provide 230W/ch.

Now the amplifier is not 100% efficient, it produces heat:
1660312717063.png

1660312734635.png

at 100W(50w/ch) it produces 22W of heat, and at 300W (150W/ch) it produces 53W of heat. And I don't think that the small heatsink on the amplifier is able to provide enough cooling on a closed case with no exhaust air or venting. At best it provides enough cooling for 5W.

At 50W(25W/ch) the amplifier has an efficiency of 80%, which means 50W*0.2=10W of heat is produced. This is twice the amount of heat the heatsink is able to dissipate.

So, my final questions to everybody are: are you planning to cook something with the amplifier? Why do you want 300W if the amplifier is not able to handle that amount of power/heat? And how much power do you really need? 10W max per channel is all you need.
Power supplies are most efficient at 50% of the load. This is their sweet spot. So if you are going to consume 20W(in reality) then use a 40W power supply.
In summary, don't bother with "big" power supplies. It is all about clean power not raw power. A clean 24W 7A power supply with less than 10mV ripple and noise will sound better than a 48V 10A noisy power supply.
You can help cleaning the power supply output with a combination of capacitors to clean the noise(small capacitor) and ripple(large capacitor)
1660314265646.png


This is why amplifier have those bulk capacitors to help cleaning in supply voltage, but we can add small capacitors to help cleaning the noise also at opamp supply pins:
1659974497467-.jpg
1659974497506-1.jpg
 
Last edited:

Joe Smith

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Their regular Aiyima power supply (32v 5a) would be capable of 160 watts, correct? So even it would probably be fine for normal volume levels...
 

dr_mick51

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Their regular Aiyima power supply (32v 5a) would be capable of 160 watts, correct? So even it would probably be fine for normal volume levels...
Yes, the stock power supply is way more than enough. I have an Aiyima A04 and I'm using a 20V 4A laptop charger (more than enough). I tried a meanwell 32V and it did not worth it, too big and no sound improvement (yes, maybe the volume pot was at lower position but who cares).
I know how much power I usually need (20-50mW "miliwatts"), So I don't care about bigger power supplies.
Use a Kill-a-wat if you have one and measure with the amp on but no sound, then play very loud music and measure again, and do the math.
 

Raindog123

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Yes, the stock power supply is way more than enough. I have an Aiyima A04 and I'm using a 20V 4A laptop charger (more than enough). I tried a meanwell 32V and it did not worth it, too big and no sound improvement (yes, maybe the volume pot was at lower position but who cares).
I know how much power I usually need (20-50mW "miliwatts"), So I don't care about bigger power supplies.
Use a Kill-a-wat if you have one and measure with the amp on but no sound, then play very loud music and measure again, and do the math.

Yep. Eg, here and here. And here. :)
 
Last edited:

375HP2482

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The power supply, worst case, has to power two 4-ohm loads, for a net load of 2 ohms.

If you feel like "upgrading" the 32 volt/5 amp power supply, a more appropriate approach would be 24peakvolts/2ohms = 12 amps at 32 volts, unless you know that your speaker loads are closer to 8 ohms than four -- unusual these days.

In other words, if anything you need more current, not more voltage.
 

dr_mick51

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The TPA3255 at 32v is able to provide a "clean" 1% THD + N output power of 110W per channel. That means 220W total. P=V*I therefore 220W/32V=6.875A from the power supply. But as I said before you don't want to run a power supply at 100% load. Between 50-70% capacity is Ok. Then we need a power supply with 6.875/0.7=aprox 10A.
But all this is unrealistic. The heatsink on the amplifier is not able to handle the heat generated by the amplifier losses at that power, which is 10% of the power produced. 220W*0.1=22W at best. You will fry the amp at that output power. The heatsink is not able to handle more than 5W without being burning hot.
But, again why do you need all that power?
The funny thing is that people move the pot to the 12 o clock position and they believe they are using half of the amplifier power. But they don't realize the amplifier has 30db Gain( I believe). That means for 1 volt RMS at the input it produces 31.6V RMS, but in reality they are feeding 0.2V (usually for music, not pure tones) which translates to 6.3V at the output at 100% on the pot. But the pot is logarithmic not linear. So in reality the output voltage is around 2V at 12 o' clock So, 2^2/4ohms=1watt.
 

Midnight Audiophile

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Would a wall wart 24v 8a power supply like this be appropriate?
It has the correct 5.5mm x 2.5mm connector. I'm running a Drok 10a adjustable PS and usually keep it at 36v. Maybe I should back it down to 24v. How do you think these would compare noise-wise. The Drok runs very quite to me and costs less but of course you have to make/buy the cables which puts them at about the same cost.
 

dr_mick51

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Would a wall wart 24v 8a power supply like this be appropriate?
It has the correct 5.5mm x 2.5mm connector. I'm running a Drok 10a adjustable PS and usually keep it at 36v. Maybe I should back it down to 24v. How do you think these would compare noise-wise. The Drok runs very quite to me and costs less but of course you have to make/buy the cables which puts them at about the same cost.
Sure, that will work. The same way the stock power supply will. It would be better to spend the money on a cheap preamp or tube preamp like the Fosi Audio, FX audio or Suca Audio. It will allow you to increase the input audio signal.
 

Midnight Audiophile

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I've got an FX Audio and an Aiyima tube preamp. One with tone control, the other without. I run Dala Spektor 2s and have them up sometimes at 90-92Db at a 40" LP. My thought was the higher amps would be better when pushing higher power. I only have a multimeter and I'm unsure about measuring the output that way. From what I've read there's nothing negative to running 8-10a since the amp will draw the current it needs. The voltage seems to be the main concern with heat, that's why I've kept mine at 36v.
 
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