AIYIMA A07 TPA3255 Review (Amplifier)

[peng]

I don't have any other power supply to test, the one from the laptop doesn't fit, if it's a high probability that the amp power supply is the culprit I could buy another one.

You mentioned the "11 volt in on-off switch and the screws in the front", can you elaborate on that, and did you use a digital voltmeter (most multimeters are nowadays)? 11 V may not be an issue at all, even 50 V would not necessary be unusual because of the capacitive coupling effect that is as long as that voltage would disappear under load. That is assuming if you were measuring the voltage between the "screws" of the chassis and ground (say the ground pin of the power outlet).

You can try to connect a resistor, say a 1 kohm one between that screw and ground (assuming that's how you got the 11 V) and see if the voltage drops to nothing or if you have an analog multimeter then you can measure it again and see that 11 v disappears.

Edit: the resistor load test is only a test to show that the 11 V may just be a phantom viltage due to capacitive coupling. Remove it after the test, if it is a phantom voltage, it is quite normal, in most cases.

Edit: I should have asked for more details first before even responding, sorry..

 

[grogi.giant]

@san I would say only this:

• You don't seem to have enough understanding of electronic circutry to do anything useful with the issue. I know Internet forums are to educate as well, but teaching basics about electricity over Internet is not the best idea.
• If you don't feel comfortable around it, simply return the unit and ask for replacement.

I did not have any issues with mine.

 

[Triliza]

You mentioned the "11 volt in on-off switch and the screws in the front", can you elaborate on that, and did you use a digital voltmeter (most multimeters are nowadays)? 11 V may not be an issue at all, even 50 V would not necessary be unusual because of the capacitive coupling effect that is as long as that voltage would disappear under load. That is assuming if you were measuring the voltage between the "screws" of the chassis and ground (say the ground pin of the power outlet).

You can try to connect a resistor, say a 1 kohm one between that screw and ground (assuming that's how you got the 11 V) and see if the voltage drops to nothing or if you have an analog multimeter then you can measure it again and see that 11 v disappears.

You mentioned the "11 volt in on-off switch and the screws in the front", can you elaborate on that, and did you use a digital voltmeter (most multimeters are nowadays)? 11 V may not be an issue at all, even 50 V would not necessary be unusual because of the capacitive coupling effect that is as long as that voltage would disappear under load. That is assuming if you were measuring the voltage between the "screws" of the chassis and ground (say the ground pin of the power outlet).

You can try to connect a resistor, say a 1 kohm one between that screw and ground (assuming that's how you got the 11 V) and see if the voltage drops to nothing or if you have an analog multimeter then you can measure it again and see that 11 v disappears.

Please ignore the 11 volt, I wasn't measuring it the right way it seems. The multimeter is a digital one (a cheap one of about 30 euro), but it is working fine as far as I can tell. Measuring the voltage between the screws/on-off switch and ground on the power outlet, gives me a reading of 90 volt. @Roland68 above said this is normal for the stock power supply 32/5A, what does that mean?

Do you think the power supply is at fault here or something else is going on?

 

[peng]

Please ignore the 11 volt, I wasn't measuring it the right way it seems. The multimeter is a digital one (a cheap one of about 30 euro), but it is working fine as far as I can tell. Measuring the voltage between the screws/on-off switch and ground on the power outlet, gives me a reading of 90 volt. @Roland68 above said this is normal for the stock power supply 32/5A, what does that mean?

Do you think the power supply is at fault here or something else is going on?

I just realized I made an assumption that I should have have, sorry! What power supply are you referring to, is it the stock power supply, the 32 V one for the amp Amir reviewed?

If it is, then I would say no, 90 V ac measured between the amp's chassis/screws and ground is not normal. I will edit my earlier post accordingly.

It may not be dangerous if it is still just some kind of phantom voltage from capacitive coupling effects, but a well designed power supply of this type should not have such high phantom voltage regardless. To know if your "90 V" is dangerous, it is best (just to be perfectly safe) to measure it with an analog meter, other do the resistor thing I suggested. Dangerous or not, if I have one like that I would return it.

 

[Triliza]

I just realized I made an assumption that I should have have, sorry! What power supply are you referring to, is it the stock power supply, the 32 V one for the amp Amir reviewed?

If it is, then I would say no, 90 V ac measured between the amp's chassis/screws and ground is not normal. I will edit my earlier post accordingly.

It may not be dangerous if it is still just some kind of phantom voltage from capacitive coupling effects, but a well designed power supply of this type should not have such high phantom voltage regardless. To know if your "90 V" is dangerous, it is best (just to be perfectly safe) to measure it with an analog meter, other do the resistor thing I suggested. Dangerous or not, if I have one like that I would return it.

It's the stock one that comes with the amp, the same as in Amir's review. I don't have an analog meter, I'll look around if I got an resistor to try that. It seems I'll have to return it, I was hoping to avoid all the hassle. Thanks for the help.

@san What are you thinking about your unit, are you going to return it?

 

[peng]

It's the stock one that comes with the amp, the same as in Amir's review. I don't have an analog meter, I'll look around if I got an resistor to try that. It seems I'll have to return it, I was hoping to avoid all the hassle. Thanks for the help.

@san What are you thinking about your unit, are you going to return it?

You can read and understand more about the phantom/or ghost voltages I referred to:

https://www.nema.org/docs/default-source/technical-document-library/phantom-voltages_rev_aug_2020.pdf

Phantom Voltages This Bulletin is intended to address the occurrence of so-called “phantom”* voltages, a phenomenon detected during the testing of electrical conductors in the field. Due to the high impedance of measuring instruments, a voltage reading may be detected on open conductors where there is no hard electrical connection to a voltage source. Conductors that are installed in close proximity to one another, and are capacitively coupled to each other, can cause this a.c. voltage reading. Such a reading could be 2 or 3 volts, or it may be as high as the voltage on the adjacent conductors. This is what is referred to as a “phantom” voltage. According to Underwriters Laboratories Inc., this can be a harmless reading and can be caused by the high input impedance of the measuring instrument, which places very little loading on the circuit under test. The capacitance is increased as the length of the run is increased. A 50-foot run may produce a pronounced capacitance effect whereas a one-foot sample may not produce any. Since the “phantom” voltage is a physical phenomenon involving very small values of capacitance, it cannot energize a load or cause physiological damage to a person. Care must be taken to be sure that the voltage reading is a phantom voltage, which is caused by improper use of high impedance multimeters, and not as a result of a cable defect or improper installation, which may result in a shock hazard. In order to help minimize the likelihood of reaching a wrong conclusion from this phenomenon, NEMA recommends the use of a Listed low impedance multimeter in place of a high impedance multimeter or other high impedance measuring device for testing on open conductors where there is no hard electrical connection. Without a low impedance measuring device, a high voltage reading is an inconclusive indication of possible faults in the cable. 2 *Phantom voltage is an industry term used to describe an unexpected voltage of a nonelectrically connected conductor.

Phantom voltage should not be confused with stray voltage which is the occurrence of an electrical potential between two conductive surfaces that should ideally not have any voltage potential between them and can result in a hazard to people and animals. This bulletin only addresses phantom voltages.

My concern is, without having the power supply in my hand for more testing, and without any information of how the stock PS is constructed and wired, I cannot say it is "normal", or "safe" to use. So as others mentioned before, return it, and may be try another one if you really like the amp a lot. I know it is a nuisance to return something, but for the sake of safety, you should do it. If you can find someone who can help you do some tests to confirm whether the voltage is of phantom nature, or a real issue that could be hazardous then you should do that first.

 

[Triliza]

You can read and understand more about the phantom/or ghost voltages I referred to:

https://www.nema.org/docs/default-source/technical-document-library/phantom-voltages_rev_aug_2020.pdf

Phantom Voltages This Bulletin is intended to address the occurrence of so-called “phantom”* voltages, a phenomenon detected during the testing of electrical conductors in the field. Due to the high impedance of measuring instruments, a voltage reading may be detected on open conductors where there is no hard electrical connection to a voltage source. Conductors that are installed in close proximity to one another, and are capacitively coupled to each other, can cause this a.c. voltage reading. Such a reading could be 2 or 3 volts, or it may be as high as the voltage on the adjacent conductors. This is what is referred to as a “phantom” voltage. According to Underwriters Laboratories Inc., this can be a harmless reading and can be caused by the high input impedance of the measuring instrument, which places very little loading on the circuit under test. The capacitance is increased as the length of the run is increased. A 50-foot run may produce a pronounced capacitance effect whereas a one-foot sample may not produce any. Since the “phantom” voltage is a physical phenomenon involving very small values of capacitance, it cannot energize a load or cause physiological damage to a person. Care must be taken to be sure that the voltage reading is a phantom voltage, which is caused by improper use of high impedance multimeters, and not as a result of a cable defect or improper installation, which may result in a shock hazard. In order to help minimize the likelihood of reaching a wrong conclusion from this phenomenon, NEMA recommends the use of a Listed low impedance multimeter in place of a high impedance multimeter or other high impedance measuring device for testing on open conductors where there is no hard electrical connection. Without a low impedance measuring device, a high voltage reading is an inconclusive indication of possible faults in the cable. 2 *Phantom voltage is an industry term used to describe an unexpected voltage of a nonelectrically connected conductor.

Phantom voltage should not be confused with stray voltage which is the occurrence of an electrical potential between two conductive surfaces that should ideally not have any voltage potential between them and can result in a hazard to people and animals. This bulletin only addresses phantom voltages.

My concern is, without having the power supply in my hand for more testing, and without any information of how the stock PS is constructed and wired, I cannot say it is "normal", or "safe" to use. So as others mentioned before, return it, and may be try another one if you really like the amp a lot. I know it is a nuisance to return something, but for the sake of safety, you should do it. If you can find someone who can help you do some tests to confirm whether the voltage is of phantom nature, or a real issue that could be hazardous then you should do that first.

Since the on-off switch gives me a slight shock when touching it (nothing painful), it shows that there is some voltage leakage in there. I'm going to return it, it was a good amp for my case.

 

[Roland68]

It may not be dangerous if it is still just some kind of phantom voltage from capacitive coupling effects, but a well designed power supply of this type should not have such high phantom voltage regardless. To know if your "90 V" is dangerous, it is best (just to be perfectly safe) to measure it with an analog meter, other do the resistor thing I suggested. Dangerous or not, if I have one like that I would return it.

Please don't be angry with me if I say this to you and everyone else so directly, but in this price range there is no "well designed power supply", or rather "high quality power supply".
This power supply costs a premium of 20-25$ to the amplifier. After deducting all costs (taxes, dealer and manufacturer profits, running costs, shipping, development, etc.) that leaves about $5 for the parts.

The Mean Well HRP-360-36 I mentioned is a multiple times better power supply from the industrial sector, net price around $100 without connections. The pure component price is about 4-5 times as high. Just imagine how much higher quality each component is.
A 10% lower component price would make this power supply significantly worse. Then you can perhaps imagine how much 80% savings make up.
The Mean Well HRP-360-36 is also not the best or most expensive 36V/10A power supply in the world, but it is a good compromise between price, performance and quality.

However, it must also be said that the supplied power supplies are surprisingly good for the price and have an excellent price/performance ratio.
Don't forget that a conventional linear amplifier power supply costs 10 times as much in this power class.

 

[peng]

Please don't be angry with me if I say this to you and everyone else so directly, but in this price range there is no "well designed power supply", or rather "high quality power supply".
This power supply costs a premium of 20-25$ to the amplifier. After deducting all costs (taxes, dealer and manufacturer profits, running costs, shipping, development, etc.) that leaves about $5 for the parts.

The Mean Well HRP-360-36 I mentioned is a multiple times better power supply from the industrial sector, net price around $100 without connections. The pure component price is about 4-5 times as high. Just imagine how much higher quality each component is.
A 10% lower component price would make this power supply significantly worse. Then you can perhaps imagine how much 80% savings make up.
The Mean Well HRP-360-36 is also not the best or most expensive 36V/10A power supply in the world, but it is a good compromise between price, performance and quality.

However, it must also be said that the supplied power supplies are surprisingly good for the price and have an excellent price/performance ratio.
Don't forget that a conventional linear amplifier power supply costs 10 times as much in this power class.

When I said well designed, I meant from safety stand point. My Nosound G2 pro is also cheap, but its 32V 5A power supply doen not cause the kind of problem Triliza is having. The Mean Well power supplies are no doubt better, but those cheap ones need to be safe for use too.

 

[Roland68]

When I said well designed, I meant from safety stand point. My Nosound G2 pro is also cheap, but its 32V 5A power supply doen not cause the kind of problem Triliza is having. The Mean Well power supplies are no doubt better, but those cheap ones need to be safe for use too.

Does the power supply of the Nosound G2 pro have a 2 or 3 pin connection cable? Have you ever measured the fault voltage between RCA ground and power ground?

Of course it shouldn't tingle when you touch it, but especially with 2-pole devices you often have an error voltage that is just under half the mains voltage.
I just measured 5 devices, 3 of which were hi-fi devices. For all of them, this voltage was between 75 and 95 volts AC. One of them is a €1000 RRP Sony CD/SACD player that was checked in the workshop a few weeks ago.
I don't think any of these devices are defective, let alone all of them. But just measure it yourself. Important for a correct measurement, no connected cables or devices other than the power cable.

 

[peng]

Does the power supply of the Nosound G2 pro have a 2 or 3 pin connection cable? Have you ever measured the fault voltage between RCA ground and power ground?

Of course it shouldn't tingle when you touch it, but especially with 2-pole devices you often have an error voltage that is just under half the mains voltage.
I just measured 5 devices, 3 of which were hi-fi devices. For all of them, this voltage was between 75 and 95 volts AC. One of them is a €1000 RRP Sony CD/SACD player that was checked in the workshop a few weeks ago.
I don't think any of these devices are defective, let alone all of them. But just measure it yourself. Important for a correct measurement, no connected cables or devices other than the power cable.

2 pole, so must be the double insulated type. I measured my G2 Pro, got only mVs. 95 V is okay if it is a phantom voltage, in industrial environment, I had seen such voltages as high as 110 V ac when long cables are involved, but again, those were phantom type so no action was taken, other than explaining that to electricians, so they don't get confused when troubleshooting power and control systems.

 

[san]

It's the stock one that comes with the amp, the same as in Amir's review. I don't have an analog meter, I'll look around if I got an resistor to try that. It seems I'll have to return it, I was hoping to avoid all the hassle. Thanks for the help.

@san What are you thinking about your unit, are you going to return it?

I sent it back to the local supplier. He tested it and saying they are not facing this issue. They also sent a video of testing the amp with voltage tester.

 

[peng]

Hi,

I bought this amp few days before. I noticed mild shock when touching the amp. When checked with a tester I see current passing through the whole body of the amp and it's affecting the whole chain.

Should I replace the device. Please advise.

Note: I have used other amps Fosi, SMSL. I never faced this issue.
View attachment 262134View attachment 262135View attachment 262136

The light of the pen was on, but if did it sustain, or just for a moment, up to a second of so?
Did you get a mild sock every time you touched it, or just one out of a few times, and were you on bare feet when that happened?

I am just still wondering if the voltage to earth was due to capacitive coupling effect, that is generally safe, and if it is, then if the supplier measured it with an analog voltmeter he wouldn't get the voltage indication. Every case can be different so for safety sake and audio performance safe, it needs to be investigated and you did the right thing investigating and return it. If I were you, I wouldn't take the unit back, but if he agreed to send you another brand new one, insist that he measures it the same you did, or use both a normal digital meter as well as a conventional analog meter, before shipping it to you. The cleanest way is not to just move on and buy another one, such as the Robsound amp that looks to be the same design, and I have no issue with it other than a very slight pop/thump during turn on/off, that is normal for such cheap amps.

 

[san]

The light of the pen was on, but if did it sustain, or just for a moment, up to a second of so?
Did you get a mild sock every time you touched it, or just one out of a few times, and were you on bare feet when that happened?

I am just still wondering if the voltage to earth was due to capacitive coupling effect, that is generally safe, and if it is, then if the supplier measured it with an analog voltmeter he wouldn't get the voltage indication. Every case can be different so for safety sake and audio performance safe, it needs to be investigated and you did the right thing investigating and return it. If I were you, I wouldn't take the unit back, but if he agreed to send you another brand new one, insist that he measures it the same you did, or use both a normal digital meter as well as a conventional analog meter, before shipping it to you. The cleanest way is not to just move on and buy another one, such as the Robsound amp that looks to be the same design, and I have no issue with it other than a very slight pop/thump during turn on/off, that is normal for such cheap amps.

The light sustains.
Yes, I feel mild shock every time I touch it. I connected a DAC to it. The DAC to gives a mild shock. But if I disconnect the DAC from the amp, no shock on the DAC.

The seller denying the issue. He says he tested it with both voltage tester and a digital metre, but no issues found on the unit. He says it may be due to some issue on my end.
But I used other amps before like Fosi and SMSL, but never faced this issue.

 

[peng]

The light sustains.
Yes, I feel mild shock every time I touch it. I connected a DAC to it. The DAC to gives a mild shock. But if I disconnect the DAC from the amp, no shock on the DAC.

The seller denying the issue. He says he tested it with both voltage tester and a digital metre, but no issues found on the unit. He says it may be due to some issue on my end.
But I used other amps before like Fosi and SMSL, but never faced this issue.

Thank you, in that case, since you only get a voltage when the DAC is connected, then it is a tough one to argue because as he said, the issue could be at your end. Have you tried connecting another source, dac, or a preamp, headphone amp?

 

[san]

Thank you, in that case, since you only get a voltage when the DAC is connected, then it is a tough one to argue because as he said, the issue could be at your end. Have you tried connecting another source, dac, or a preamp, headphone amp?

I didn't say I get voltage only when a DAC is connected. I'm saying the Voltage is passed to other devices too when connected to the amp.

 

[chinna]

Not sure if this already posted, now AIYIMA 07 is being shipped with 36v 6.0A Power brick instead of old 32v 5AMP. That is same brick that is supplied with A08 Pro, and provide a good bit of extra power(additional 56W) and higher voltage. As per many reviews this is sweet voltage for best performance and clean output.

As per AIYIMA website it should provide 85W per channel at 8 OHMs. I bought 3 of these to run 6 surround/ATMOS channels. This AMP is pretty clean (no hiss) and plenty loud, and very efficient too. In normal operation it was only using 4W of power.

AIYIMA A07 - US Warehouse Ship

Description: The TPA3255 is a high-performance Class D power amplifier with Class D efficiency and true to high-end sound quality. The device features an advanced integrated feedback design and proprietary high-speed gate driver error correction (Purepath Ultra HD). The dual 300W shocking bass...

www.aiyima.com

 

[Ashoka]

My aiyima 07 went kaput after 5 months of use. really upto chinese standard. BEWARE on cheap from China.

 

[Toku]

My aiyima 07 went kaput after 5 months of use. really upto chinese standard. BEWARE on cheap from China.

If you can use it for 5 months, it's still good. I had an experience like this before.
I bought 3 BRZHiFi TPA3255 and MA12070 amps and they broke in just one day.
When I turned the power switch on and off two or three times during the test, the power would not turn on forever.
I will never buy a BRZHiFi product again because of this experience.

 

[chinna]

My aiyima 07 went kaput after 5 months of use. really upto chinese standard. BEWARE on cheap from China.

Sorry about that.
But curious, Is it the power supply that is failed or the amplifier?
Or it just switch or something like that? The reason I am asking is, I connected all 3 of these to a controlled/triggered outlet when my main receiver and amp turns on. So main switch on the AMP is always on, just the power to brick is on/off based on trigger. Also Volume is set fixed as it is calibrated to that volume. So pretty much it will be never touched after the initial setup.