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AIYIMA A07 TPA3255 Review (Amplifier)

I know that the lower the voltage, the easier it would be on those 50VDC Nichicons, especially right next to that "inappropriate heatsink."
The biggest problem I have with the A07 is right here: small heatsink right next to capacitors
 
Seems like everyone is focused on power supply rather than the amp. May I ask those who own this, if I upgrade from a tpa3116 amp to the A07, what difference can I expect?
 
The biggest problem I have with the A07 is right here: small heatsink right next to capacitors

If/when they fail, I've already got a simple kludge/fix in mind.

Seems like everyone is focused on power supply rather than the amp. May I ask those who own this, if I upgrade from a tpa3116 amp to the A07, what difference can I expect?

Having owned both, the phrase "night and day" comes to mind: much more heft, "oomph," and ample headroom to handle thunderous peaks without even a hint of clipping. The A07's TPA3255 is two generations newer, much more powerful, and considerably more sophisticated than the TPA3116. To my ear the A07 sounds both clearer and stronger than the highly acclaimed Adcom GFA-535 -- designed by Nelson Pass -- that I swore by back in the day.
 
I am of the opinion that one shouldn't have to make such a fix in the first place. :p

Me too -- but I paid all of $45.10 apiece for my two A07s and, if those caps fail in a few years and I have to fix that design flaw with a couple of new (63VDC 105^C) Nichicons -- glued in sideways near the 3.5mm jack and connected to the stubs of the failed caps' leads with ordinary 20AWG hookup wire -- to revive it, there will be very little resentment. Besides, being along in years, I may well expire before the amp does, even with that flaw. :cool:
 
Fortunately, my SMPS can provide any voltage the A07 can use up to 49+VDC (unloaded) on down to and past the minimum needed for it to function. I was just curious as to what voltage would be best thermally -- I doubt I could hear "a bit less distortion," but I might be wrong. I know that the lower the voltage, the easier it would be on those 50VDC Nichicons, especially right next to that "inappropriate heatsink."
Actually it is perhaps not distortion, but noise, that is "a bit less" according to Amir's graph. Sorry for the mistake.
 
Is the stock PSU earth grounded?

I don't think so, if you look at the power cord. And there is a class II marking on the 32V unit.

AIYIMA A07 Power Supply.jpg
 
Me too -- but I paid all of $45.10 apiece for my two A07s and, if those caps fail in a few years and I have to fix that design flaw with a couple of new (63VDC 105^C) Nichicons -- glued in sideways near the 3.5mm jack and connected to the stubs of the failed caps' leads with ordinary 20AWG hookup wire -- to revive it, there will be very little resentment. Besides, being along in years, I may well expire before the amp does, even with that flaw. :cool:
You might want to read the layout guidelines in the TI datasheet before doing that. They're where they are for a reason.
 
... I'm trying to figure out where is the point of diminishing returns, where you pay for something more of it's appearance and brand sticker than what it actually does.

DT - As are, I believe, many of the folks who frequent ASR and do so with an eye or ear of skepticism.

I got interested in audio as a kid in college in the late seventies, when a thousand dollars barely bought a decent quality system with speakers and cassette deck (and turntable) and an amp/ receiver over 25 watts. And in those days, $1000 was big money when the minimum wage was $2.35 an hour.

Today, with a cell phone, a DAC (dongle), a Class D amp (hopefully with a power supply ) and a pair of good desktop speakers like the Elacs, etc, a college kid in 2020 can own a system for three hundred 2020 dollars that would give my 1978 system a serious run for the money.

Ain’t technology great?

To answer your question more directly, with quality speakers attached, I’m zeroing in on the conclusion that spending over $750 to $1000 gets you a system that, to my diminishing level of hearing, quickly becomes more about looks and how it makes you feel than the quality of the sound you hear.

As for connects and cables, I think that point is reached somewhere around $10 as fellow ASR cynics will frequently point out!

To wit, per my earlier posts in this thread, the fact that I just picked up an AO7 to play with goes to this point: For $65, today, I can buy a Class D, throw away amp that will sound almost as good as the Harmon Kardon Citation amp and separate pre amp that took a big chunk of my summer savings in 1978 just puts a stupid grin on my face. (And to be able to roll op amps with this AO7 - which I’ve never tried before - is all the better. Frankly, I’m surprised there isnt a separate thread on op amps for the 07 or mods for the case for fans, drilling the case etc. to better cool this little amp like we see on single board computer forums like the Raspberry Pi.)

My $ 0.02.

Cheers
 
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The heat is ... a result of small closed space and inappropriate heatsink. This is rather a toy than an amplifier. What else would we expect at such price. If anyone wants a serious product, look elsewhere.

Well, technically speaking :) , the heat is the result of a less than 100% efficiency of an amplifier. And is the function of the drawn (or output) power and the efficiency coefficient... Per TI datasheet, TPA3255 chip efficiency is about 80% at 50W... Leading to about 10W of thermal, that can be handled by the said heatsink/volume (I hope the designers did do their thermal-analysis homework). Combined with the couple of folks' thermal snapshots here, this indicates that the A07 is much more than "just a toy". [Did not we used to refuse to accept a "perfect" $100 DAC too? :) ]
 
Well, technically speaking :) , the heat is the result of a less than 100% efficiency of an amplifier. And is the function of the drawn (or output) power and the efficiency coefficient... ]

... and you, as a designer, have to treat it with a choice of proper heatsink, case and cooling. And this did not happen here. You cannot operate this amp at full TI specs, because you would boil it. In better case it would trigger off itself.
 
Why? I hope for more test of similar amps. The TPA3255 obviously has potential so why should we not want to know which of these amps are good value and which are garbage?
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.
 
... and you, as a designer, have to treat it with a choice of proper heatsink, case and cooling. And this did not happen here. You cannot operate this amp at full TI specs, because you would boil it. In better case it would trigger off itself.

I respectfully disagree. And so are multiple thermal snapshots, eg, on page 11. You also cannot operate the chip _above_ the TI power spec, but this is not the point. But, thank you.
 
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
Or, something else might be at play... At some point, aluminum was worth way more than gold & platinum - in the mid 1850’s the annual production of aluminum in the US was less than 93kg)... And then they developed the Hall–Heroult process... One can't stop progress! :)
 
DT - As are, I believe, many of the folks who frequent ASR and do so with an eye or ear of skepticism.

I got interested in audio as a kid in college in the late seventies, when a thousand dollars barely bought a decent quality system with, speakers and cassette deck (and turntable) and an amp/ receiver over 25 watts. And in those days, $1000 was big money when the minimum wage was $2.35 an hour.

Today, with a cell phone, a DAC (dongle), a Class D amp (hopefully with a power supply ) and a pair of good desktop speakers like the Elacs, etc, a college kid in 2020 can own a system for three hundred 2020 dollars that would give my 1978 system a serious run for the money.

Ain’t technology great?

To answer your question more directly, with quality speakers attached, I’m zeroing in on the conclusion that spending over $750 to $1000 gets you a system that, to my diminishing level of hearing, quickly becomes more about looks and how it makes you feel than the quality of the sound you hear.

As for connects and cables, I think that point is reached somewhere around $10 as fellow ASR cynics will frequently point out!

To wit, per my earlier posts in this thread, the fact that I just picked up an AO7 to play with goes to this point: For $65, today, I can buy a Class D, throw away amp that will sound almost as good as the Harmon Kardon Citation amp and separate pre amp that took a big chunk of my summer savings in 1978 just puts a stupid grin on my face. (And to be able to roll op amps with this AO7 - which I’ve never tried before - is all the better. Frankly, I’m surprised there isnt a separate thread on op amps for the 07 or mods for the case for fans, drilling the case etc. to better cool this little amp like we see on single board computer forums like the Raspberry Pi.)

My $ 0.02.

Cheers
Great read. Thank you.
Some DIY forums have extensive threads on these kind of devices and mods made to them.
 
... and you, as a designer, have to treat it with a choice of proper heatsink, case and cooling. And this did not happen here. You cannot operate this amp at full TI specs, because you would boil it. In better case it would trigger off itself.

1. The protection features of the chip are impressively sophisticated, so a triggered shutdown is the most likely result of an overheating incident. Even with its tiny ventless case, skimpy heat sink, and dubious component placement, the A07 will probably "keep its pants on" without any permanent damage in the event of serious overheating.

2. Virtually nobody needs to "operate this amp at full TI specs" in its likely home stereo applications.

All in all, the A07 is a reasonable, very low-cost gamble of a purchase. Want a better design that makes the most of the chip's potential? Be patient and wait for what Johan is developing at Allo -- and no doubt pay considerably more, perhaps nearly as much as an IcePower- or Hypex-based equivalent.
 
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