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Aiyima A07 PRO

conradj

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My A07 Pro seems to work fine with good Bluetooth power output, but I need your advice. Since I too have the ELAC Debut 2.0 B6.2' do you think the OPA 1656 is a good option replacement. I remember you found them harsh in the beginning....or maybe a warmer OPA like 2134 ...
Also i'm messing with running 3 speakers per channel instead of just the ELACs, that changes things. It's why i went for this 48V SMPS both for higher voltage and its better current delivery. Still have to make a better DC cable to go from the SMPS to the amp. Parts aren't all here.
 
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conradj

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Yeah, I love the A07 non pro. @trungdtmc shows us the components needed to make it truly shine. Better caps and inductors are what it needs. He shows those WIMA bits too in his video.
Yeah, dang it; those Coilcraft inductors he shows won't fit here in my A07, those middle 2. They're too wide by abt 5mm each and all prolly too long by a mm or so. Will keep looking. Prolly Sagami units will fit.

--And i might try an adhesive carbon thermal pad for between the heatsink and the amp chip, instead of a piece of copper.
 
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isaac507

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Having read various posts and review videos about the A07 Pro, I still find that I prefer the sound of the A07 non-Pro. Anyway, I found another mini amp that appears to be the Bluetooth version of the A07. According to a post I found, the measurements and internal components of this amp are quite similar to those of the A07.






S861c3c7430d24ec48af99cd2ae13f7c1G.jpg
 

Jacob8275

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Having read various posts and review videos about the A07 Pro, I still find that I prefer the sound of the A07 non-Pro. Anyway, I found another mini amp that appears to be the Bluetooth version of the A07. According to a post I found, the measurements and internal components of this amp are quite similar to those of the A07.






The components of the A07 and the Neohipo DA300 are same, I think they are from same factory.
 

conradj

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Having read various posts and review videos about the A07 Pro, I still find that I prefer the sound of the A07 non-Pro.

Not me. After having run them side by side, i prefer the A07 Pro. It's most obvious at higher volumes.

Even the heatsink is better on the A07 Pro. The new version of the A07 i have has a 9cm X 3cm heatsink, and the A07 Pro has one that's 7.5cm X 4cm, 3 cm2 better and with closer fin spacing.

i just have to replace that big cap with one that's rated for higher voltage. With the A07 non-Pro i'll have to replace a lot more bits.
 

grogi.giant

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How does the Line-out work? Does it follow Volume and Tone Controls? Will it output the BT signal, when amp playing from BT?
 
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Scrufboy

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By the way I have it hooked up with a 2.5x5.5 dc screw terminal. very clean. lots of power going into the back unlike some of these dc wires. they barely have 4 strands of copper in some of them. I verified with Aiyima if this is ok to set the amp up like this using a 40 volt battery and they said its fine. just that there would be lots of power. im only using a pair of those 40 watt b652 airs and it barely will make them move.
Nice... i use super robust custom DC cables made from Canare 4S6 with Oyaide DC connectors
 
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Scrufboy

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How does the Line-out work? Does it follow Volume and Tone Controls? Will it output the BT signal, when amp playing from BT?
First off... We don't have the schematics... would be nice... but that is not practical... BUT - What we do know though - Line out is affected by the U16 Op Amp... I do believe the two differential op-amps might be a part of things too as far as output to line out. I could be wrong. I most likely am wrong. Again we either need the schematics - or someone diligent like @conradj or @trungdtmc to trace all that and tell us what is what. But we can investigate to find out some things.

I have my A07 Pro hooked up to an Aiyima A3001 sub amp... I control volume with a Schiit Magni+ pre-amp... When I raise the volume there... both the A07 Pro and the A3001 increase in volume - obviously. The volume knob on the A07 Pro however does not affect the output for line out though. I can turn the A07 Pro all the way down and my sub still plays.

As far as Tone... No... The tone controls do not affect the output as far as I can see... I don't think It would make sense to have the line out affected by the tone control.

Bluetooth is just an input option.. So it would stand to reason that everything would work the same way posted, no matter the input.
 
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Scrufboy

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nd i might try an adhesive carbon thermal pad for between the heatsink and the amp chip, instead of a piece of copper.
Remember - The heat-sink already has an aluminum wafer and two plastic risers on the screws. This aluminum wafer is 1.0mm thick - You would need a carbon thermal pad the same thickness as the aluminum wafer, or to eliminate the risers... This though would put the chip at risk of stress and cracking under pressure if you tighten things down too tightly or unevenly. The spacers/risers on the screws work to prevent that. You also have to worry about uneven spreading of thermal paste. Again, something the spacers are there to help with. A carbon pad could replace the paste though.

Copper is better than carbon for heat conductivity.... Copper's high thermal conductivity allows heat to pass through it quickly. Other desirable properties of copper in heat exchangers include its corrosion resistance, biofouling resistance, maximum allowable stress and internal pressure, creep rupture strength, fatigue strength, hardness, thermal expansion, specific heat, antimicrobial properties, tensile strength, yield strength, high melting point, alloy, ease of fabrication, and ease of joining.

Thermal conductivity of Copper is 401 W/mk

Thermal conductivity of Carbon is 62.5 W/mk

But most Carbon pads - thermal performance 35 W/mk

Thermal Grizzly brags their Carbonaut pad has a thermal conductivity of 62.5 W/mk

That is a huge difference... Copper being better. But you could use the carbon pad in place of paste for sure. I would still use a copper wafer though. The goal being to move the heat from the chip quickly. The copper being that repository - Moving it then to the aluminum heat sink.

* Carbon can have a negative coefficient of thermal expansion. When the material is heated, it will shrink. Carbon fiber atoms are often fixed along the x and y axes. The plane bonds that hold the fibers in place in the x and y axes are covalent. This leaves the z direction unfixed and held together by much weaker Van Der Waals forces.

When carbon fiber is heated the atoms will begin to vibrate, mostly in the z direction. When this occurs, the vibrating atoms will pull on neighboring atoms. This entire phenomenon will bring the atoms closer together and constrict the material in the x and y directions. The material will continue to shrink as the heat increases and the atoms begin to vibrate more.

Here is what I bought for the voltage regulator heatsinks... I cut and shaped them to size. I was lucky that these were the same thickness as the aluminum wafer of the heatsink for the chip.


I have a whole bag of these... A ton left over... Want some?
 
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conradj

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Remember - The heat-sink already has an aluminum wafer and two plastic risers on the screws. This aluminum wafer is 1.0mm thick


I have a whole bag of these... A ton left over... Want some?
Dang it again. i just ordered some!

i've also ordered a sheet of graphite rather than carbon, so i'll be sticking the graphite over most of the bottom surface of the heatsink, and then pasting the copper slug on the graphite, with some graphite paste.

Also i've ordered stuff, thin little plastic boxes and copper tape, to make some covers to slip over the existing inductors of the A07 i just got, to see if that will add enough electromagnetic shielding to make them sound better at higher volumes.

A whole lot cheaper, and a great deal less work, than buying and soldering on CoilCraft shielded inductors. Those are like $11CDN a piece plus shipping. Haven't found any Sagami's in this country, from reputable shops.

--i can see i'd have to replace those 4 film capacitors as well just to make room for the CoilCraft inductors.
 
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conradj

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The 48V SMPS has a 2 pin GX16 DC connector, so i'm getting some of those as well as some all metal power supply plugs with big enough of a hole for feeding thru 16awg speaker wire. That should be good enough, until i feel like soldering the wire directly onto the amp PCB. A lot of down sides to that tho.

The SMPS comes with a reasonable power supply wire already, am using that for now.
 

conradj

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Hm, ok. Copper tape won't do. Will have to get a sheet of galvanized steel. Bring a magnet to the hardware store to check.
 

Wheely

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Not true! The Aiyima A07 is a great little product. And many others out there - no, they are not going to last 30 years like our old Sony, Marantz, Yamaha equipment, but they are good if you think of them having about a 10-year life. (Yes, the e-waste problem is not to be dismissed, but when I look at the lifespan of TVs, refrigerators, coffeepots, toaster ovens and cars, just to name a few, our little class D amp issues seem to be but a small part of that...)

I personally feel a separate BT adapter provides the best solution, BUT after a little weirdness at the beginning, my SMSL AO 100 has a very solid BT connection with my older iPhone. I put the volume on the phone to near max and get room-filling sound from the AO 100 at about -20 on the volume control. With the 6 ohm speakers I use with it presently, the unit has only about 45 wpc but that's still fine for a medium sized room.

The best "capture" I've had on the cheap side though is from my old stalwart, the Logitech BT receiver. If it's on, it WILL connect with your device...resistance is futile...it overrides everything else. If it's on when I pull in the driveway, just for instance, it will grab the connection from my car. I'm sure there is a newer gen Logitech product with some of the latest BT codecs available now.

Practical limitations exist. If you have low efficiency speakers or a larger room, a Hypex or Purify based amp is surely a better and more satisfying choice. I think problems arise when people push these smaller, cheaper amps to the absolute max of their power capabilities. They don't have cooling vents for the most part, and the capacitors are often very close to the chip's heatsink. Pushing to high output will degrade them faster - just makes sense.
On the bright side. Aiyima heard my claim and refunded me on the amp. I wanted to keep it. It just wont work for my needs
 
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Scrufboy

Scrufboy

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Also i've ordered stuff, thin little plastic boxes and copper tape, to make some covers to slip over the existing inductors of the A07 i just got, to see if that will add enough electromagnetic shielding to make them sound better at higher volumes.
Link me to the boxes.... I like the idea of DIY shielding. I've also seen people cover their caps with copper tape. However, I do need to put some knowledge on this... I often use aluminum and copper tape. Making a layered shield. I have read that nickel works when incorporated into 3 layers.
Would be a nice DIY hack if it works.
 
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Scrufboy

Scrufboy

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Copy... I wired my SMPS outputs to DC sockets... Shoot me some pics of what you got going on.
The 48V SMPS has a 2 pin GX16 DC connector, so i'm getting some of those as well as some all metal power supply plugs with big enough of a hole for feeding thru 16awg speaker wire. That should be good enough, until i feel like soldering the wire directly onto the amp PCB. A lot of down sides to that tho.

The SMPS comes with a reasonable power supply wire already, am using that for now.
 

conradj

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Link me to the boxes.... I like the idea of DIY shielding. I've also seen people cover their caps with copper tape. However, I do need to put some knowledge on this... I often use aluminum and copper tape. Making a layered shield. I have read that nickel works when incorporated into 3 layers.
Would be a nice DIY hack if it works.

i decided that copper tape won't do. It provides RF shielding but little magnetic shielding which is prolly what's needed here. Espesh those 2 inductors next to each other. They prolly each project a magnetic field that causes resonances in the other. That's why people prefer the shielded inductors in this type of amp PCB layout.

If only i had a steel plate of the right size, i'd just drop it into a baggie and put it between them and see if that makes a difference.

Going to head to the hardware store and find a sheet of 26 gauge steel, try and make some little boxes out of that to cap them.

Still trying to think thru what i'll need. Tin shears for one. The right kind of tape to line the inside. Something to line the bottom edges of the steel, something else to keep them in shape.

The hardware store's bloody website is throwing an error when i try to make a check out, going to have to head there physically to buy the bits.
 
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Galliardist

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@Holmz - You changed this and posted - I have the top cover laying on top, open 1 cm each side, I think sounds better now...

Stop doing this....
I forgot to turn off the Pro yesterday for 24 hours with a 48v 5a power supply...glad nothing happened, I have the top cover laying on top, open 1 cm each side so don't get too hot, I think sounds better now after accidentally break in...
You mean, “stop quoting people accurately”?

It is exactly what was said. And @Holmz was generous. People here have measured for burn in, and it shows up as a myth when actually tested for. He only asked nicely.

While we’re at it, this thread is getting more and more subjective and not in a good way.

I thought that around here, modifications to equipment should be shown to be safe and demonstrate objective improvements. To be clear, I’m not saying you shouldn’t mod the amp or any of tbe other things mentioned. Far from it. I don’t care if you blow up a couple of these things on the way or anything either, as long as you stay safe and don’t burn down any buildings.

We can’t both have fun and learn unless we have results. You can measure temperatures and check that your remediation is right or even necessary, you can measure the amp before and after to show improvement. You don’t just get to say output is higher or say it sounds better on ASR, people expect evidence.

Sorry to be so blunt, but you’ll get much worse from others here if you carry on this way.
Good luck with the experiments, I’ll leave you to it.
 
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Scrufboy

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While we’re at it, this thread is getting more and more subjective and not in a good way.
Obviously, this thread, which is mine... Has been subjective from the start, both in design and goal. Do try to keep up.
 
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