AIYIMA A07 TPA3255 Tear Down

[DuncanTodd]

I will measure if LM4562 and OPA2134 makes a difference.

Looking forward for your tests.
I can't remember which others were liked. Maybe the OPA2064 and 1656. Aiyima rep said they found the LM4562 to be better and they are offering it as an upgrade when you buy those models.
Here are some quotes from the rep:
https://www.audiosciencereview.com/...amp-do-you-recommend.9148/page-14#post-538599
https://www.audiosciencereview.com/...tpa3255-amp-do-you-recommend.9148/post-572200

 

[YSC]

This is TI eval board + analog schematics. Please note the distance between the heatsink and electrolytes.

Maybe that's why they opt for the nichicons? TBH will this amp be better off just make it "topless" with enough air circulation. I personally don't want anything closed with so much power and heat inside

 

[IVX]

I have some proto on that chip used in the post-filter FB configuration. THD+N with a resistor load is ok something around 0.01% or a bit less at -3db of max power but the clipping behavior is absolutely awful. I spend a week fixing it or rather to reduce its ringing but anyway I can hear the clipping is very dirty(also quite loud On click-noise, Off is ok). Pre-filter FB configuration has no ugly clipping, however, it has THD 0.05% at my speaker system(resistor load is much better but who needs that?). To be honest, post-filter FB doesn't really much help with real speaker load as well.

 

[martin900]

Depending on how much space there is between the PCB and the case, it might be worthwile to put a thermal pad between the PCB and bottom of the case and another one betweet the heatsink and top, just to give it some more thermal transfer to the case.

 

[Pulkass]

This is a teardown of the AIYIMA A07 TPA3255 Class D Amplifier I just reviewed. I gave it high marks for very low distortion at extremely low budget price. Question was raised on the revision of the board and thermal characteristics of the unit so here we are.

I was very pleased to see the PCB having silk screen markings for all surface mount parts:

View attachment 103028

The business end, i.e. TI TPA3255 IC is buried under that gold color heatsink. To the left we have some power supply circuits and input buffers made up of common NE5532 opamps. To the right we have reservoir capacitors and output filtering. Speaking of those caps, I was very surprised to see them having the top capacitor brand, Nichicon:
View attachment 103029

Someone should do the forensics and tell us if they are the real deal or fakes.

Soldering job on speaker terminals and such is acceptable.

The back side shows smudges and imprints of other boards:


View attachment 103030

They could have cleaned it but at these prices is not something you expect. It should work fine.

I let the amp run for about 6 minutes driving 20 watts x 2 into 4 ohm load. The heatsink was too hot to touch and temp kept climbing:

View attachment 103031

TI specs the chip at 90% efficiency at max power. At 20 watts, it is running around 80% efficient so is producing 8 watts of heat into that little heatsink. With no vent or circulation, I would not deploy this amp for continuous high power use. The junction temp is rated quite high at 150 degrees C though so it is a tough little chip to kill. It has a thermal shutdown of 155 degree C so if it does that, you best not push it remotely that hard.

The two aforementioned electrolytic caps are sitting pretty close to that heatsink. If they not nichicons, they may go first.

Conclusions
Sans the pedigree of the caps, I really don't see corners being cut here given the target market and very low cost of the unit. It could have been much worse than it is. With power supply being external, safety risks lay there, not inside this amp. The metal enclosure should contain any fires and such in that unlikely event.

So not bad!

------------
As always, questions, comments, recommendations, etc. are welcome.

Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

This is a teardown of the AIYIMA A07 TPA3255 Class D Amplifier I just reviewed. I gave it high marks for very low distortion at extremely low budget price. Question was raised on the revision of the board and thermal characteristics of the unit so here we are.

I was very pleased to see the PCB having silk screen markings for all surface mount parts:

View attachment 103028

The business end, i.e. TI TPA3255 IC is buried under that gold color heatsink. To the left we have some power supply circuits and input buffers made up of common NE5532 opamps. To the right we have reservoir capacitors and output filtering. Speaking of those caps, I was very surprised to see them having the top capacitor brand, Nichicon:
View attachment 103029

Someone should do the forensics and tell us if they are the real deal or fakes.

Soldering job on speaker terminals and such is acceptable.

The back side shows smudges and imprints of other boards:


View attachment 103030

They could have cleaned it but at these prices is not something you expect. It should work fine.

I let the amp run for about 6 minutes driving 20 watts x 2 into 4 ohm load. The heatsink was too hot to touch and temp kept climbing:

View attachment 103031

TI specs the chip at 90% efficiency at max power. At 20 watts, it is running around 80% efficient so is producing 8 watts of heat into that little heatsink. With no vent or circulation, I would not deploy this amp for continuous high power use. The junction temp is rated quite high at 150 degrees C though so it is a tough little chip to kill. It has a thermal shutdown of 155 degree C so if it does that, you best not push it remotely that hard.

The two aforementioned electrolytic caps are sitting pretty close to that heatsink. If they not nichicons, they may go first.

Conclusions
Sans the pedigree of the caps, I really don't see corners being cut here given the target market and very low cost of the unit. It could have been much worse than it is. With power supply being external, safety risks lay there, not inside this amp. The metal enclosure should contain any fires and such in that unlikely event.

So not bad!

------------
As always, questions, comments, recommendations, etc. are welcome.

Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Kindly, what thermo camera do you use ??? Thanks

 

[mhardy6647]

Thanks Amir.
I have the A04, and I know that one for sure had a few builds. I don't have the right screwdriver to open it and see which one I got lol.

A set of security bits is easy to come by and comes in terrifically handy nowadays

 

[DuncanTodd]

A set of security bits is easy to come by and comes in terrifically handy nowadays

You mean like a multi option screwdriver? I have such with like 12 different screw heads but non of them fit. I also have a few others, no go. It seems like a very small/shallow hex screw.

 

[mhardy6647]

You mean like a multi option screwdriver? I have such with like 12 different screw heads but non of them fit. I also have a few others, no go. It seems like a very small/shallow hex screw.

no, I mean a set of security bits. The one in question might be odd, but I'd be surprised if a comprehensive set of security bits wouldn't take care of things.

Here's a cheap but comprehensive one. Not 'pro quality' bits, but infinitely better than nothing.

These are less cheap (still cheap, in all senses of the word, though) but nice because they are long -- one of the tricks used on some appliances is to put special screws deep down narrow clearance holes. Rascals.

 

[JohnYang1997]

This is TI eval board + analog schematics. Please note the distance between the heatsink and electrolytes.

View attachment 103105

View attachment 103106

But this.

 

[Lorenzo74]

This is TI eval board + analog schematics. Please note the distance between the heatsink and electrolytes.

View attachment 103105

View attachment 103106

Would be really nice if @amirm could test this board, se we can have a sort of ground truth of the great TPA3255.
At least we can confirm the TI specs.
Looking forward
Best Wishes

 

[JohnYang1997]

Would be really nice if @amirm could test this board, se we can have a sort of ground truth of the great TPA3255.
At least we can confirm the TI specs.
Looking forward
Best Wishes

https://quantasylum.com/blogs/news/ti-tpa3255-evm

 

[DuncanTodd]

no, I mean a set of security bits. The one in question might be odd, but I'd be surprised if a comprehensive set of security bits wouldn't take care of things.

Here's a cheap but comprehensive one. Not 'pro quality' bits, but infinitely better than nothing.

These are less cheap (still cheap, in all senses of the word, though) but nice because they are long -- one of the tricks used on some appliances is to put special screws deep down narrow clearance holes. Rascals.

Thanks.
I know these sets, just didn't know they are called that. What I have is a mini set with just about 10 or 12 bits.

 

[Dzhaughn]

Many of those you listed are much worse than genuine NE5532.

But, like tubes, that's the point. Look at it as an opportunity to double the price!

 

[MrPeabody]

This is TI eval board + analog schematics. Please note the distance between the heatsink and electrolytes.

View attachment 103105

View attachment 103106

I don't see the op-amps ... maybe they are likewise under the heat sink? I looked at the cost of TI's evaluation boards a while back, on Digikey I think, and was surprised at the high cost. I expect that it would be prohibitively expensive for anyone to manufacture and sell complete amplifiers using the TI evaluation boards.

 

[pma]

I don't see the op-amps ... maybe they are likewise under the heat sink? I looked at the cost of TI's evaluation boards a while back, on Digikey I think, and was surprised at the high cost. I expect that it would be prohibitively expensive for anyone to manufacture and sell complete amplifiers using the TI evaluation boards.

Bottom side of the PCB. Yes the quality is expensive.

 

[daniboun]

Hi,

What about THD+N @5W / 4R ?
What about Sinad 5W / 4R ?

Would be nice to know for this Aiyima A07.

 

[pma]

Hi,

What about THD+N @5W / 4R ?
What about Sinad 5W / 4R ?

Would be nice to know for this Aiyima A07.

@JohnYang1997 has posted the link to the excellent test. The TI board is much better than the AIYIMA.

https://quantasylum.com/blogs/news/ti-tpa3255-evm

 

[daniboun]

@JohnYang1997 has posted the link to the excellent test. The TI board is much better than the AIYIMA.

https://quantasylum.com/blogs/news/ti-tpa3255-evm


View attachment 103155

I already know this test... is from March 2019 )

I am talking about the AIYIMA A07, so again :

What about THD+N @5W / 4R ?
What about Sinad 5W / 4R ?

 

[infinitesymphony]

It was experimented to some degree already. LM4562 and a couple of the OPA ones were prefered over the shipped one, likely on subjective basis though. a DIY forum or two did a lot of modifications on this unit and others.

LM4562 would be my first choice based on op-amp rolling a CMoy back in the day.

In the CMoy thread, @JohnYang1997 recommended OPA2156 and OPA2189.

 

[bigredrobotninja]

Does anybody know how the 3.5mm/RCA inputs work (i.e. are they just wired together)? Should you avoid connecting different sources at the same time?