AIYIMA A07 TPA3255 Review (Amplifier)

[pma]

120W/4ohm
This is about just maximum what I can get from this amplifier when using a big 50Vdc linear power supply with a 270VA transformer. Above 120W there is a fast rise of noise and high order harmonics - signs of clipping. 173W/4ohm with THD = 0.78%.

 

[Bruce Morgen]

120W/4ohm
This is about just maximum what I can get from this amplifier when using a big 50Vdc linear power supply with a 270VA transformer. Above 120W there is a fast rise of noise and high order harmonics - signs of clipping.

View attachment 104156

I'd wager 100 WPC or so is more than enough for most of us -- and for less than $100 including an SMPS capable of supplying adequate current, the thing is an incredible bargain even it fails a few years down the road. Enough said...

 

[pma]

I'd wager 100 WPC or so is more than enough for most of us -- and for less than $100 including an SMPS capable of supplying adequate current, the thing is an incredible bargain even it fails a few years down the road. Enough said...

Yes, the little box works better than I expected, so far. However, the power supply is crucial. It has to be beefy and and well filtered. Or maybe a clean SMPS. But not the units that @amirm had used in the test - I understand he did not have another option.

 

[Bruce Morgen]

Yes, the little box works better than I expected, so far. However, the power supply is crucial. It has to be beefy and and well filtered. Or maybe a clean SMPS. But not the units that @amirm had used in the test - I understand he did not have another option.

Yeah. My SMPS is rated at 480 watts and FWIW I added a little extra shunt capacitance across its output. I definitely agree that the little power bricks available for Amir's testing were woefully inadequate. You mentioned 270VA as your big linear's transformer rating -- how much DC current do you figure it can source after rectification and (what must be an awful lot of) filtering?

 

[pma]

Yeah. My SMPS is rated at 480 watts and FWIW I added a little extra shunt capacitance across its output. I definitely agree that the little power bricks available for Amir's testing were woefully inadequate. You mentioned 270VA as your big linear's transformer rating -- how much DC current do you figure it can source after rectification and (what must be an awful lot of) filtering?

I will measure it - the transformer continues to supply current even if overloaded, just more heat. It is a big EI. My guess is up to 10A. Filter capacitance is 10 000 uF.

The smaller supply is regulated linear 30V, it has very very small ripple even if loaded. You could see the measurement 5W/4ohm that is free from hum components. This supply gives only about 1- 1.5A and A07 gave 20W, clean 20W/4ohm with it. This confirms that the power supply is a crucial part with this amplifier, because it has PSR only about 65 dB.

With my 50V power supply I believe I would get 300W/4ohm at THD = 10%. But I am afraid to overload the chip thermally, regardless protection.
Everything seems to confirm TI datasheet specs, only that they allow tons of distortion.

 

[Swoof]

Well mine just arrived today (US based) in the branded black box from Amazon with the power supply included. I also had ordered the parts express 36V 5a power supply for something hopefully safer and more powerful but it is making horrendous noise so will be sending that back. 32V 5a supply that came with unit is perfectly quiet.

Volume knob is around 18 on the 0 to 60 on the a07. M200 DAC is at -10dB and this thing is driving my DBR62s to uncomfortable listening levels in my small living room. Listening for an hour and unit is cool to the touch. The m200 puts out up to 2.7v in pre mode so perhaps that's why I'm able to keep volume knob on a07 so low.

Red light on power switch is very annoying.

 

[Ralferator]

For me I agree that too many such devices is a waste of resources. Those spending such low sums of money are likely doing so knowing that they are taking a chance and are willing to sacrifice some performance to save money, which is fine. Those entertaining spending more are taking a much larger risk and arguably need the type of information such a review produces to make a more impactful spending decision. I don't think the skills and equipment Amir has are well invested if he tests too many such products. I am not saying don't test some, just try to strike a balance. With inexpensive equipment Amir might get flooded with requests and have little time for testing other gear.

Many people don't have so much money to spend. People who have the money to pay thousands of dollars for an amplifier can probably just buy another one when they are not satisfied. I think it's much more interesting to see low priced equipment perform really good than expensive equipment because from expensive equipment you should be able to expect good performance. Also to me it seems like Amir likes to find low price audio gear that performs much above it's price range. Look at the JBL Stage A130 or JBL LSR range for example. Many very high priced speakers can't compete. It should not be about price but about performance and Amir's reviews show that good audio equipment doesn't have to be expensive.

 

[Jdunk54nl]

Many people don't have so much money to spend. People who have the money to pay thousands of dollars for an amplifier can probably just buy another one when they are not satisfied. I think it's much more interesting to see low priced equipment perform really good than expensive equipment because from expensive equipment you should be able to expect good performance. Also to me it seems like Amir likes to find low price audio gear that performs much above it's price range. Look at the JBL Stage A130 or JBL LSR range for example. Many very high priced speakers can't compete. It should not be about price but about performance and Amir's reviews show that good audio equipment doesn't have to be expensive.

Agreed, show me another amp that is 6" x 4" (or there about) that can fit so easily on my desktop, and perform as good as this. There are not a lot of options for something like this. I have been looking for quite some time for a small desktop amp that performs well. The next closest I found was the hypex nc252mp amps in a ghent case at over 4x the cost. The loxjie a30, but it didn't perform much better and has things I don't want. I don't need a DAC, I just need an amp.

I am actually thinking about getting another one for my garage.

 

[DuncanTodd]

Many people don't have so much money to spend. People who have the money to pay thousands of dollars for an amplifier can probably just buy another one when they are not satisfied. I think it's much more interesting to see low priced equipment perform really good than expensive equipment because from expensive equipment you should be able to expect good performance. Also to me it seems like Amir likes to find low price audio gear that performs much above it's price range. Look at the JBL Stage A130 or JBL LSR range for example. Many very high priced speakers can't compete. It should not be about price but about performance and Amir's reviews show that good audio equipment doesn't have to be expensive.

+1
This category works for all kinds. I can't return stuff I don't like, so I won't buy expensive gear even if I can afford it, unless I'm certain I need it.

 

[DuncanTodd]

There is a very slight hiss when the input is muted, but it's only audible with my ear pressed against the tweeter - something you'd never hear from a listening position.

As there are already several members who got this following the review, can anyone attest to the above comment? My A04 has that.

 

[escape2]

Volume knob is around 18 on the 0 to 60 on the a07.

Does the volume knob have 60 actual clicks throughout its range or is it smooth/infinite adjustment?

 

[Bruce Morgen]

I will measure it - the transformer continues to supply current even if overloaded, just more heat. It is a big EI. My guess is up to 10A. Filter capacitance is 10 000 uF.

The smaller supply is regulated linear 30V, it has very very small ripple even if loaded. You could see the measurement 5W/4ohm that is free from hum components. This supply gives only about 1- 1.5A and A07 gave 20W, clean 20W/4ohm with it. This confirms that the power supply is a crucial part with this amplifier, because it has PSR only about 65 dB.

With my 50V power supply I believe I would get 300W/4ohm at THD = 10%. But I am afraid to overload the chip thermally, regardless protection.
Everything seems to confirm TI datasheet specs, only that they allow tons of distortion.

The data sheet includes both 10% and 1% max power specs, plus some very informative graphs.

 

[Bruce Morgen]

Does the volume knob have 60 actual clicks throughout its range or is it smooth/infinite adjustment?

It's just an ordinary two-section potentiometer -- no 'actual clicks" at all.

 

[Jdunk54nl]

As there are already several members who got this following the review, can anyone attest to the above comment? My A04 has that.

Nothing from mine unless I max out volume knob to 60, which would be semi expected, at least from me.

 

[pma]

The data sheet includes both 10% and 1% max power specs, plus some very informative graphs.

Thank you, I have studied all the available TI literature, the datasheet, EVM, PFFB paper and also QA401 measurements. This is a first step to study available documents, isn’t it. The most real data are in the QA401 measurements and the PFFB document, including strange nonlinearities at 6kHz. I will now stop posting in this thread, because I am collecting data for my own review. It is a time consuming process, as I do not have an automated measuring system.

 

[Bruce Morgen]

Thank you, I have studied all the available TI literature, the datasheet, EVM, PFFB paper and also QA401 measurements. This is a first step to study available documents, isn’t it. The most real data are in the QA401 measurements and the PFFB document, including strange nonlinearities at 6kHz. I will now stop posting in this thread, because I am collecting data for my own review. It is a time consuming process, as I do not have an automated measuring system.

Fair enough -- thanks for your input.

 

[Swoof]

As there are already several members who got this following the review, can anyone attest to the above comment? My A04 has that.

I'm getting a very slight hiss. It's about 10% as loud as a JBL 305p hiss, have to hold ear to tweeter, also it doesn't increase much with volume knob. cranked up.

 

[mhardy6647]

Does the volume knob have 60 actual clicks throughout its range or is it smooth/infinite adjustment?

It's just an ordinary two-section potentiometer -- no 'actual clicks" at all.

Whew! 'cause I was gonna wonder whether they were linear or logarithmic clicks.

 

[A Surfer]

Many people don't have so much money to spend. People who have the money to pay thousands of dollars for an amplifier can probably just buy another one when they are not satisfied. I think it's much more interesting to see low priced equipment perform really good than expensive equipment because from expensive equipment you should be able to expect good performance. Also to me it seems like Amir likes to find low price audio gear that performs much above it's price range. Look at the JBL Stage A130 or JBL LSR range for example. Many very high priced speakers can't compete. It should not be about price but about performance and Amir's reviews show that good audio equipment doesn't have to be expensive.

Anybody buying audio gear has disposable income. By definition buying audio gear means the income is disposable. I wasn't suggesting Amir only measure gear that costs thousands of dollars, I agree some budget gear is worthwhile and great to measure, just not too much of it. You are also making assumptions about the people who buy expensive gear. maybe they have saved for a very long time and hence the review is needed to help them finally decide to put a ton of savings into a purchase. maybe they are considering going into debt to buy some upstream gear. Just because people have spent money doesn't mean they are rich.

I for one recently sold off a ton of headphone gear that took me years of savings to collect. With those funds and taking on about $1500 in debt I purchased some expensive speakers and subs. Without that context if I just told you what I have you would probably assume I have lots of money. Nope. I have barely worked in almost three years as I went back to graduate school and have survived off of money from being a teaching assistant at university and a part time job so I have no money yet I have nice audio gear. You can't assume people with nice gear have lots of money that they can simply waste.

I can't imagine Amir wants to fill up his testing time with budget gear. Some yes, absolutely, I never said otherwise.

 

[DuncanTodd]

I can't imagine Amir wants to fill up his testing time with budget gear. Some yes, absolutely, I never said otherwise.

I think there is a good mix of budget and higher end. Remember the selection is dependent mostly on what members are willing to buy or ship over + occasional samples from manufacturers. Ideally I would even preferred it all to be from members, as manufacturers products could potentially be reference builds that will show better measurements.