Aiyima A07 Max Amplifier Review

[AIYIMA:GUO]

Thanks guys for discussing this. I might go as well with X7R caps, I had not realised how well they fit in the electrolytics footprints and I have some laying around.
TI eval board uses 4 1uF. These ones GRM31CR72A105KA01L

But I would love @AIYIMA:GUO or @AIYIMA the reason they have chosen to go with the electrolytics.

And what do you guys plan to do with C6? It is also at PSU voltage

View attachment 353332

C6 is the main power supply filter capacitor, used to filter out high-frequency noise from the power supply.

 

[trungdtmc]

I replaced the capacitors with regular x7r 100v capacitors, nothing special
This is the measurement result before and after my changes, the results may be slightly different from amirn's, lower noise results in lower THD+N

 

[dr_mick51]

I replaced the capacitors with regular x7r 100v capacitors, nothing special
This is the measurement result before and after my changes, the results may be slightly different from amirn's, lower noise results in lower THD+N
View attachment 353407

Very nice, thank you. Any improvement is welcome.

 

[trungdtmc]

And here are the changes I made to the input power part of the main 12v step down

 

[MCH]

C6 is the main power supply filter capacitor, used to filter out high-frequency noise from the power supply.

Hi @AIYIMA:GUO what I wanted to know is if there is a reason for you choosing to use the 4 small electrolytic capacitors instead of X7R that seems to be what TI recommends. Thank you.

 

[AIYIMA:GUO]

Hi @AIYIMA:GUO what I wanted to know is if there is a reason for you choosing to use the 4 small electrolytic capacitors instead of X7R that seems to be what TI recommends. Thank you.

What we choose here is the overall aesthetics of the PCBA, so here we use a slightly larger solid capacitor. I saw your comparison after I replaced the capacitor. The difference is only a few 0.000% (this difference is basically negligible). Thank you for your product suggestions and efforts.

 

[trungdtmc]

What we choose here is the overall aesthetics of the PCBA, so here we use a slightly larger solid capacitor. I saw your comparison after I replaced the capacitor. The difference is only a few 0.000% (this difference is basically negligible). Thank you for your product suggestions and efforts.

And those are 50v rate caps

 

[dr_mick51]

What we choose here is the overall aesthetics of the PCBA, so here we use a slightly larger solid capacitor. I saw your comparison after I replaced the capacitor. The difference is only a few 0.000% (this difference is basically negligible). Thank you for your product suggestions and efforts.

Aiyima, It may not seem a lot but those few 0.00xx% mean almost 2dB lower THD+N (according to Trung's measurements) and that's a great advantage specially in a website like this one, where -2dB can put you above the competition.
I know that most of the people are not very mod-oriented or with the tools, time and maybe knowledge to do the modifications themselves, so this type of upgrade worth it, and also allows to prove that upgrading components make a difference (which many people here don't believe or agree with), and it can be measured. Thank you Trung.

 

[MCH]

I personally don't care about the aesthetics of the PCB nor about a couple of dB, but I don't like to run the amp at 48V with 50V rated caps. I appreciate their honesty though, hence the like to their post.

 

[dr_mick51]

I personally don't care about the aesthetics of the PCB nor about a couple of dB, but I don't like to run the amp at 48V with 50V rated caps. I appreciate their honesty though, hence the like to their post.

Hey, MCH. Me neither, but it gives me peace of mind knowing that better components are used. If it sounds good that's all I need. But we cannot also forget that good measurements are like marketing and publicity nowdays. It might be the placebo effect or not, but people feel happier if their believes are validated with numbers.

I'm not going to say that everybody, but for example many people could felt happy with their gear before, until that same gear is measured here, and measured poorly or not as good as they expected. Suddenly that gear does not sound as good as before anymore.

I completely agree with you that if an amplifier is publicized to work with a 48V PS, should have components able to safely handle that voltage, and not running right at the limit. Most of the time people only think about capacitors rated voltage, but there are other components which are sensitive to that higher voltage. I'm talking about the voltage regulator. The voltage regulators bring down the voltage by "burning" the excessive voltage. This causes the regulators to heat up. The more voltage the regulator needs to "burn" the more heat it produces and its internal temperature rises. This is why I don't agree on using 48V power supplies on these type of amplifiers.

Being honest, why do people need to use a 48V power supply? Is their required output voltage swing to be that high?
A 48V DC signal can handle up to a 48V AC peak(not RMS, not peak-peak) signal. This means it can handle (without clipping) 0.707x48V=33.93VAC rms. That will require an input signal of 33.93V/28.18 (gain equivalent to 29dB)=1.2Vrms of audio signal (not test tones at 0dBFS). Real music plays in "average" -12dBFS (or 4 times lower voltage that what the DAC normally can produce. This means we need a single ended DAC with a 4.8V rms at (0dBFS) output to produce a 1.2V rms musical signal at -12dBFS, do we have those DACS?). All this translates into a 143.95W/ch (this is beyond the amplifier capacity for a clean signal) at 8ohms, and requires a 6A 48V Power supply (assuming an ideal amplifier with no extra power used for any extra functions, and not having any losses). Is that really the amount of power we need or use? Just because we use a higher voltage power supply it does not mean the amp will deliver more power. If we don't increase the input signal then the amp will not take advantage of that higher output voltage swing. The input signal (audio signal and potentiometer position) is what determines the output signal. If the amplifier voltage is not high enough to handle that output signal then the amplifier clips. It's only in this case where a bigger power supply shows a benefits. If the output AC signal is only 5V (5*5/8ohm or 3.125W), then there is no benefit on having a 48V PS.

Let's do a real life example. We have a DAC capable of outing 2V rms at 0dBFS, this means 0.5V rms of real music at the amplifier input with the potentiometer at max. 0.5Vrms x 28.18 gain = 14.09VACrms output signal. Because this is AC it needs a DC carrier higher than the peaks of the AC signal, otherway it clips the signal. So 14.09/0.707=19.92V peak. So we only need a 20V DC power supply to take advantage of all the musical signal we can provide with that DAC. I know people will say hey Mick but what happen with those cannons of whatever symphony and explosions or those massive peaks or whatever? Ok, the A07 Max comes with a 36V DC rms power supply. This allows up to 25.45AC rms output swings, which therefore allows up to 0.903Vrms of input signal before clipping, this is an extra 5.1dB headroom compared to the 0.5Vrms before. All this assuming we are maxing up the potentiometer (I really doubt we are maxim up the amplifier power in first place). Does anybody remember the PMPO vs RMS power discussions from years ago? those inflated values compared to the RMS ones. This is exactly what happens with those peaks which occur during 0.5 seconds or so. The amplifier can deliver 10 times more power during those short moments. So no need to worry about.
Most of the people use (knowing or unknowing) a 0.5V input signal (from a 2V 0dBFS DAC), but then use the potentiometer at 12 o' clock. Depending on the pot type (Linear or Log) this means a completely different input signal right at the chip inputs, way lower than the DAC output signal. For example, I'm going to talk about my personal case. In average my output signal is no more than 2V at the speaker terminals. This means 0.5W with 8ohms nominal speakers. This allows me to play music at 85dB from 1meter or so. This is more than enough for me. This means that if 2V AC rms is the output, then the input signal at the chip is 2V/28.18= 0.0709V. That is nothing compared to the 0.5V signal coming out of the DAC. This is the effect of the pot. This is 7 times lower voltage or 14% of the input signal. The potentiometer position is at 12 o' clock.
I know every case is different. Maybe you have low sensitivity speakers(85dB vs 88dB needs twice the power, 1W instead of 0.5W), maybe your listening distance is longer (6dB drops everytime you double the distance. 2m vs 1m requires 4 times for power. Now, again 4W instead of 1W). So 4W/ch is all you need under these new conditions.

Are we maxing up the potentiometer? if so, maybe all we need is a higher input signal. I'm an advocate of using a preamp to increase your input signal instead of a bigger and higher voltage power supply. If not, maybe all we need is to increase the pot a little more. Don't be afraid to increase it beyond 12 o' clock (this is where all the juice is squeezed) 12 o'clock is just 10-15% of the input signal on these Log Pots.

 

[MCH]

Hey, MCH. Me neither, but it gives me peace of mind knowing that better components are used. If it sounds good that's all I need. But we cannot also forget that good measurements are like marketing and publicity nowdays. It might be the placebo effect or not, but people feel happier if their believes are validated with numbers.

I'm not going to say that everybody, but for example many people could felt happy with their gear before, until that same gear is measured here, and measured poorly or not as good as they expected. Suddenly that gear does not sound as good as before anymore.

I completely agree with you that if an amplifier is publicized to work with a 48V PS, should have components able to safely handle that voltage, and not running right at the limit. Most of the time people only think about capacitors rated voltage, but there are other components which are sensitive to that higher voltage. I'm talking about the voltage regulator. The voltage regulators bring down the voltage by "burning" the excessive voltage. This causes the regulators to heat up. The more voltage the regulator needs to "burn" the more heat it produces and its internal temperature rises. This is why I don't agree on using 48V power supplies on these type of amplifiers.

Being honest, why do people need to use a 48V power supply? Is their required output voltage swing to be that high?
A 48V DC signal can handle up to a 48V AC peak(not RMS, not peak-peak) signal. This means it can handle (without clipping) 0.707x48V=33.93VAC rms. That will require an input signal of 33.93V/28.18 (gain equivalent to 29dB)=1.2Vrms of audio signal (not test tones at 0dBFS). Real music plays in "average" -12dBFS (or 4 times lower voltage that what the DAC normally can produce. This means we need a single ended DAC with a 4.8V rms at (0dBFS) output to produce a 1.2V rms musical signal at -12dBFS, do we have those DACS?). All this translates into a 143.95W/ch (this is beyond the amplifier capacity for a clean signal) at 8ohms, and requires a 6A 48V Power supply (assuming an ideal amplifier with no extra power used for any extra functions, and not having any losses). Is that really the amount of power we need or use? Just because we use a higher voltage power supply it does not mean the amp will deliver more power. If we don't increase the input signal then the amp will not take advantage of that higher output voltage swing. The input signal (audio signal and potentiometer position) is what determines the output signal. If the amplifier voltage is not high enough to handle that output signal then the amplifier clips. It's only in this case where a bigger power supply shows a benefits. If the output AC signal is only 5V (5*5/8ohm or 3.125W), then there is no benefit on having a 48V PS.

Let's do a real life example. We have a DAC capable of outing 2V rms at 0dBFS, this means 0.5V rms of real music at the amplifier input with the potentiometer at max. 0.5Vrms x 28.18 gain = 14.09VACrms output signal. Because this is AC it needs a DC carrier higher than the peaks of the AC signal, otherway it clips the signal. So 14.09/0.707=19.92V peak. So we only need a 20V DC power supply to take advantage of all the musical signal we can provide with that DAC. I know people will say hey Mick but what happen with those cannons of whatever symphony and explosions or those massive peaks or whatever? Ok, the A07 Max comes with a 36V DC rms power supply. This allows up to 25.45AC rms output swings, which therefore allows up to 0.903Vrms of input signal before clipping, this is an extra 5.1dB headroom compared to the 0.5Vrms before. All this assuming we are maxing up the potentiometer (I really doubt we are maxim up the amplifier power in first place). Does anybody remember the PMPO vs RMS power discussions from years ago? those inflated values compared to the RMS ones. This is exactly what happens with those peaks which occur during 0.5 seconds or so. The amplifier can deliver 10 times more power during those short moments. So no need to worry about.
Most of the people use (knowing or unknowing) a 0.5V input signal (from a 2V 0dBFS DAC), but then use the potentiometer at 12 o' clock. Depending on the pot type (Linear or Log) this means a completely different input signal right at the chip inputs, way lower than the DAC output signal. For example, I'm going to talk about my personal case. In average my output signal is no more than 2V at the speaker terminals. This means 0.5W with 8ohms nominal speakers. This allows me to play music at 85dB from 1meter or so. This is more than enough for me. This means that if 2V AC rms is the output, then the input signal at the chip is 2V/28.18= 0.0709V. That is nothing compared to the 0.5V signal coming out of the DAC. This is the effect of the pot. This is 7 times lower voltage or 14% of the input signal. The potentiometer position is at 12 o' clock.
I know every case is different. Maybe you have low sensitivity speakers(85dB vs 88dB needs twice the power, 1W instead of 0.5W), maybe your listening distance is longer (6dB drops everytime you double the distance. 2m vs 1m requires 4 times for power. Now, again 4W instead of 1W). So 4W/ch is all you need under these new conditions.

Are we maxing up the potentiometer? if so, maybe all we need is a higher input signal. I'm an advocate of using a preamp to increase your input signal instead of a bigger and higher voltage power supply. If not, maybe all we need is to increase the pot a little more. Don't be afraid to increase it beyond 12 o' clock (this is where all the juice is squeezed) 12 o'clock is just 10-15% of the input signal on these Log Pots.

I forgot to mention that I use my aiyimas for passive subs and I am repurposing the original sub PSU that gives 48V. But I agree with your points.

 

[AIYIMA]

Thank you for your product suggestions. We will give your feedback to the engineering department. When we make the next generation of products, we will avoid these small details.

 

[AIYIMA:GUO]

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[danielha]

Hi folks,

I have one quite simple question I can not find answer to !

I have an unused center speaker (Focal 700V) I'd like to use as a connected speaker. So I plan to buy an A07 Max, set it up to mono output and plug my mobile phone with a jack<-> cinch cable. This will be more than plenty for a 12 m² home office. However what will I hear on the speaker ? Both right & left channels "monoed" together or either right OR left channel ?

Do you know any other small inexpensive D class amplifier that I could use for this matter (with possible mono output setup) ?

Daniel

 

[dr_mick51]

Hi folks,

I have one quite simple question I can not find answer to !

I have an unused center speaker (Focal 700V) I'd like to use as a connected speaker. So I plan to buy an A07 Max, set it up to mono output and plug my mobile phone with a jack<-> cinch cable. This will be more than plenty for a 12 m² home office. However what will I hear on the speaker ? Both right & left channels "monoed" together or either right OR left channel ?

Do you know any other small inexpensive D class amplifier that I could use for this matter (with possible mono output setup) ?

Daniel

Greetings.
I understand what you are planning to achieve. But this is not the "mono" you are looking for. The Aiyima A07 MAX (the same goes to Fosi ZA3) outputs one single channel (mono). So the whole amplifier only processes whatever is connected to the right channel RCA(if not mistaken, or Left. In the end it is only one RCA is used as source).
What you need for your case it's a DSP where you can "mix" L + R RCA channels into 1 output and then connect that single RCA cable into any amplifier. Or in this case one Aiyima A07 MAX in mono mode.

There are other "passive" adapters. Which use resistors to join both signals together. You may want to try it. This is from Amazon, but I believe they can be found anywhere:
Adapter

 

[danielha]

Greetings.
I understand what you are planning to achieve. But this is not the "mono" you are looking for. The Aiyima A07 MAX (the same goes to Fosi ZA3) outputs one single channel (mono). So the whole amplifier only processes whatever is connected to the right channel RCA(if not mistaken, or Left. In the end it is only one RCA is used as source).
What you need for your case it's a DSP where you can "mix" L + R RCA channels into 1 output and then connect that single RCA cable into any amplifier. Or in this case one Aiyima A07 MAX in mono mode.

Hi dr_mick51,

Thanks for your answer.

Obviously it could not be just that easy

So I do need both amp and DSP which is not as cheap as I had in mind. Any advise on a cheap DSP ?

Daniel

 

[dr_mick51]

Hi dr_mick51,

Thanks for your answer.

Obviously it could not be just that easy

So I do need both amp and DSP which is not as cheap as I had in mind. Any advise on a cheap DSP ?

Daniel

Hi Daniel. I updated my reply to add a link to a passive adapter which is cheaper than DSP and works for your particular need. A DSP is better (of course) but more expensive and probably overkill for what you need unless you plan to use its other functionalities (which I use) as Channel mix, Crossovers: Low Pass Filter for Subwoofers and High Pass Filter for your main speakers, Gain, Equalizer, Limiters, etc..

Option 1

Option 2 Option 3 Option 4 all these are identical (different price)

Option 5

Option 6 This is what I use, just for the BT functionality. But I think all of them will work perfectly for you.

Note: These are car audio DSPs, they are ugly I know, but you can hide it and also after you have already set it you won't need to touch it again (or you might, one of the reason I bought the one with BT). The only other problem is you need a 12V power supply to power it.

 

[danielha]

Hi Daniel. I updated my reply to add a link to a passive adapter which is cheaper than DSP and works for your particular need. A DSP is better (of course) but more expensive and probably overkill for what you need unless you plan to use its other functionalities (which I use) as Crossovers: Low Pass Filter for Subwoofers and High Pass Filter for your main speakers, Gain, Equalizer, Limiters, etc..

Option 1

Option 2 Option 3 Option 4 all these are identical (different price)

Option 5

Option 6 This is what I use, just for the BT functionality. But I think all of them will work perfectly for you.

Note: These are car audio DSPs, they are ugly I know, but you can hide it and also after you have already set it you won't need to touch it again (or you might, one of the reason I bought the one with BT). The only other problem is you need a 12V power supply to power it.

dr_mick51,

I know a DSP is overkill in my case. I just want to listen to music easily and don't need much functionnalities. I'll take your inexpensive solution to use a stereo to mono passive adapter.

Thanks again !
Daniel

 

[maty]

Aiyima A07 vs A07 Max stereo vs A07 Max mono x2

AIYIMA A07 MAX - KING OF SPEED & PUNCH

 

[Stoneager90]

Correct me if I'm wrong but it looks like the A07 max has a cleaner pbtl implementation than the ZA3. Im looking at the THD+N plot from the A07 max Amirm posted and not seeing a similar 10db increase from the ZA3. Am I missinterperting that plot? Lurker new account all that good stuff