AIYIMA A70 Stereo Amplifier Review

[ICIETDIYEUR]

Good morning
For a 3e Audio A7 to be able to provide 34A (as you say above) it would need at least a power supply of around 38A (take into account the ~90% efficiency), even with 51Vcc.
Afterwards he would have to be able to dissipate them (LOL)...
Regarding the AIYIMA A70: it is not because it is written 48V on the back of the device that it is necessarily limited to that (I am sure not if you take the time to look at the circuit), moreover 3eAudio has voluntarily 'limited' its power supply to 51V but you can apply up to 53.5V, in fact up to 56.5V max. if the load impedance is greater than or equal to 6 Ohms (see TI datasheet concerning the TPA3255).
If you have to provide clarification here, at least try to be precise by providing verifiable elements and not simple 'rumors'.
Don't take this the wrong way because I have nothing against you at all: I'm just trying to provide good information
Have a good day.
Sincerely.

 

[john61ct]

Good morning
For a 3e Audio A7 to be able to provide 34A (as you say above) it would need at least a power supply of around 38A (take into account the ~90% efficiency), even with 51Vcc.

LOL no. The A7 Mono DOES produce over 30A under high load draws, there is no "if" there.

Peak Watts are relatively consistent, e.g. 480W peaks into 2 ohms, or for Stereo, 200+W per channel into 4 ohms

That 51V is just at the output from the PSU. The INTERNAL voltage is widely varying as the Amps demanded varies.

How Class D PWM switch works, like a Buck DC Converter when high current is needed (peak transients not long term) voltage is reduced out of the amplifier to the speaker.

But at the PSU, well under 10A is being drawn by the input rails, seems lower but at 51V means ~500W

much lower voltages internally on the way to the output rails, so much higher Amperes.

Capiche?

 

[john61ct]

3eAudio has voluntarily 'limited' its power supply to 51V but you can apply up to 53.5V, in fact up to 56.5V max.

That is dangerous misinformation, please stop, people might follow that as if advice.

Those numbers are just relevant to the TPA3255 chip specs alone, not to the overall design. There are plenty of other components inside the box that will get burned at those levels.

Even using 52V all the time will likely reduce longevity. Hence the value of adjustability in a PSU, no need to even go over 48V except when you are squeezing out every SPL dB.

Which if that is frequent better to buy a more powerful power amp in the first place.

 

[ICIETDIYEUR]

john61ct: have you studied the diagrams of the 3eAudio A7 and AIYIMA A70 amplifiers?
It seems not...
Why do you want to systematically contradict me?
Do you live in a world where your desire is to be systematically right (or your 'devious' ways of making people believe it)?
Science is something objective but to talk about it you have to have experience
That said, it's up to you to cook sausages on these devices with such power output (and heat dissipation), you will at least have won that before they give up the ghost or worse, they catch fire
Capiche?

 

[NTK]

john61ct: have you studied the diagrams of the 3eAudio A7 and AIYIMA A70 amplifiers?
It seems not...
Why do you want to systematically contradict me?
Do you live in a world where your desire is to be systematically right (or your 'devious' ways of making people believe it)?
Science is something objective but to talk about it you have to have experience
That said, it's up to you to cook sausages on these devices with such power output (and heat dissipation), you will at least have won that before they give up the ghost or worse, they catch fire
Capiche?

Since when it is a good idea to exceed the clearly labelled manufacturers' specified supply voltage limit of 48 V? Are you going take on the liability for any damages that are not covered by manufacturers' warranty? For a minuscule increase of 20*log10(53.5/48) = 0.94 dB output power?

 

[antcollinet]

LOL no. The A7 Mono DOES produce over 30A under high load draws, there is no "if" there.

Peak Watts are relatively consistent, e.g. 480W peaks into 2 ohms, or for Stereo, 200+W per channel into 4 ohms

That 51V is just at the output from the PSU. The INTERNAL voltage is widely varying as the Amps demanded varies.

How Class D PWM switch works, like a Buck DC Converter when high current is needed (peak transients not long term) voltage is reduced out of the amplifier to the speaker.

But at the PSU, well under 10A is being drawn by the input rails, seems lower but at 51V means ~500W

much lower voltages internally on the way to the output rails, so much higher Amperes.

Capiche?

Don't think it works quite like that.

Firstly the output rails are constant 48V DC. The variable output voltage is created by pulse width modulation of that onto the output terminal via an LC filter. While it is technically possible for output current to exceed the PSU rating short term via energy storage in the filter inductor or bulk capacitance, or just short term PSU capability, I can't see it coming close to the 30A+. you state, even as switching transients which would by blocked by the output filter - and which have nothing to do with the music signal in any case. Even less so at low output volts - because at low output volts, the speaker will draw lower current - not higher.

Also - even into 2 ohm the a7 mono is limited to around 450W except at the extreme capacitive phase angle where it reaches 480.


EDIT : done some more looking - at the extreme of 60degree phase angle and 2ohm impedance magnitude, current would ramp up to about 22A at around 44V to give the real power 480W - at which point PSU current is going to be 10A plus losses (10+%?). So probably not sustainable except for transient power delivery. And still somewhat short of the 30+A mentioned above.

Obviously here - lower output volts due to low impedance - so current still required, and increased due to phase angle.

 

[john61ct]

I was only using A7 as an example, which 52A limit is indeed clearly specified, and I personally would not exceed, hence my use of 51V as an upper limit, likely for occasional use only, if indeed the case (as heat sink) got too hot

Nothing personal here at all, most of the time I am not even aware of handles exceptvfor those few whose expertise I actively want to heed.

 

[gwing]

I was only using A7 as an example, which 52A limit is indeed clearly specified, and I personally would not exceed, hence my use of 51V as an upper limit, likely for occasional use only, if indeed the case (as heat sink) got too hot

Nothing personal here at all, most of the time I am not even aware of handles exceptvfor those few whose expertise I actively want to heed.

I think the point is that the maximum voltage for the amplifier is indeed clearly specified, even printed on the case, but it is 48V not 52V.
There will of course be some components in the amplifier which may be individually rated for more than 48v but that doesn't increase the voltage rating for the amplifier as a whole.

 

[john61ct]

I think the point is that the maximum voltage for the amplifier is indeed clearly specified, even printed on the case, but it is 48V not 52V.

Not the A7 mono, look at the online manual

> DC38V-52V

That is exactly its designed advantage in delivering moar power and current - transient peaks indeed over 30A.

With all the caveats I already gave

 

[gwing]

Not the A7 mono, look at the online manual

> DC38V-52V

That is exactly its designed advantage in delivering moar power and current - transient peaks indeed over 30A.

With all the caveats I already gave

The photos posted above showing the actual devices ( I think both A70 mono and Stereo versions) clearly show the maximum voltage as 48V. Is there something you cannot understand about this?

Edit: I subsequently noticed the photo was of the A70 and you were referencing the A7. So I actually wasted my time looking at the online manual for the A07 which also stated clearly
"7. Power input interface ( DC power supply, maximum 48V)"

 

[john61ct]

The photos posted above showing the actual devices ( I think both A70 mono and Stereo versions) clearly show the maximum voltage as 48V. Is there something you cannot understand about this?

If that is what the **A7 Mono** label says, then it is incorrect.

The spec I posted - from the official manual - has been verified hundreds of times by members I trust. Also by the horse's mouth @3eaudio

I hope that helps.

 

[SuicideSquid]

Anyone have any thoughts about using this guy as a dedicated subwoofer amplifier?

I'm building a matching pair of 8" subs for my main listening area, using Hivi D8.4mk2 drivers. They're average efficiency and I don't typically listen at very high levels (peak maybe 90dB during a movie, music never louder than 85dB peak). I can't see needing more than 100 watts per channel. I was going to salvage a couple plate amps from old Paradigm 10" subs (100watts each) but thought this might be a more elegant solution (and give me more flexibility in the future if I want to add another Buckeye Hypex multichannel 250wpc amp, and use that to drive them instead if I feel like I need more power).

Any reason I definitely shouldn't do this?

 

[antcollinet]

Any reason I definitely shouldn't do this?

Seems to do quite well at low frequency power compared to some. If 100W is enough I can't see why you shouldn't.

 

[Oaziz5]

Hello everyone. Does anyone know the real output impedance of the AIYIMA A70 and what its damping factor is?

 

[john61ct]

Google says

into an 8-Ohm Load: 400
into a 4-Ohm Load: 200

might be hallucinating ofc but really, does it matter?

PFFB means 0.02Ω

 

[Oaziz5]

Google says

into an 8-Ohm Load: 400
into a 4-Ohm Load: 200

might be hallucinating ofc but really, does it matter?

PFFB means 0.02Ω

Thank you for the reply. I’m looking for independent measurements. In my opinion, this is one of the most important amplifier parameters. An amp can have low noise and good frequency response, but if the damping factor is poor, it won’t be able to properly control the speakers, and the sound can turn into a mess.

 

[MaxwellsEq]

Thank you for the reply. I’m looking for independent measurements. In my opinion, this is one of the most important amplifier parameters. An amp can have low noise and good frequency response, but if the damping factor is poor, it won’t be able to properly control the speakers, and the sound can turn into a mess.

Damping factor and output impedance are obviously related. However, pretty much any modern solid state amplifier has more than sufficient damping factor.

 

[mlsstl]

If you're worried about the dampening factor on a power amp then stay away from tube amps. It'd be tough to design an amp using the TPA3255 chip that didn't have good dampening specs. Otherwise, these days it a bit like still worrying about jitter on a modern DAC.

 

[antcollinet]

If you're worried about the dampening factor on a power amp then stay away from tube amps. It'd be tough to design an amp using the TPA3255 chip that didn't have good dampening specs. Otherwise, these days it a bit like still worrying about jitter on a modern DAC.

Sorry to be picky - it is damping, not dampening. Dampening is what happens when you leave something out in the rain.

 

[mlsstl]

Sorry to be picky - it is damping, not dampening. Dampening is what happens when you leave something out in the rain.

Thanks for the correction! One can always depend on the internet to spot things like this!