Aiyima A07 Max Amplifier Review

[XaVierDK]

The volume control is also the on/off switch. So I can't test the on/off pop the usual way as that would be at minimum level compared to other amps with separate power switch that are at full gain. So while not practical, I turned the amp on/off using the AC plug:

Worth noting, the popping is only there for AC on/off.
In daily use the power switch is only a standby-switch, which retains power to an anti-pop circuit. So in normal use you'd have no popping, basically ever.

 

[space_duck]

Haha that is no "auto mute",
that's a faulty unit.

I had similar issue with SMSL A0300, it was annoying as hell. Returned it.

Had some back and forth messages with Fosi and they confirmed it's intentional for that amp. Very annoying.

 

[musicforcities]

Well, it looks like their volume pots are probably the factor here, right? Hopefully they can source an improved part for that for subsequent production.

This is another reason I'd like to see one of these makers develop a "pure amp," either as monoblocks or a stereo amp. Then we can control volume with a better pot at the preamp stage... (I like the Hypex amps but frankly, for me, with my smaller room setups, 150 wpc at 8 ohms is overkill. Would be nice to get a TI3255 pure amp in that $200-300 window.)

Yeah, cheap pots, or lack of qc /testing on decent pots suck. Be nice to have at lease a switch to bypass it (but adds expense). I doubt it’s worth making a separate pot-less version from the manufacturers pov.

audibility of the imbalance depends on overall db levels as the imbalance looks more or less consistent throughout the range. But both the consistency and that channels don’t at least converge closer at max vol in that graph makes me wonder if the imbalance is really from the pot or from someplace else. i guess it’s more likely if it’s a linear pot. But I wonder if there is some mismatch elsewhere. With these gain levels, components at the input stage would need to be tightly matched and the pcb layout well thought out.

Well a vol defeat switch would be nice at least.

I suppose if it really bothers you you could bypass the vol pot by soldering two jumper wires and resistors to the bottom of the pcb. I would guess you would want to put resistors equal to the pot value from wiper to one pin and just a wire from wiper to the other pin. You may be able to use the pot itself instead of resistors as long as you leave it at max and depending on the circuit. should not have to remove the pot itself and thus should be able to keep its power switch function (which I presume uses distinct pins). If the imbalance is still there at least the pot is eliminated as the primary cause.

But that’s a lot of trouble for such a low cost thing. But it would be easy for manufactures to use the same pcb and just use a button or on off knob.


Man, the old fashioned pre amp “balance” pot is looking pretty useful now.

 

[ninetylol]

Any harm in sending the Aiyima A07 MAX a full 2.1 volt signal from a Smsl SU-1 with its 1v input sensitivity?

Amp is not maxed but at about 2 o clock.

 

[Zek]

full 2.1 volt signal from a Smsl SU-1

Full 2.1 volt signal from a Smsl SU-1 is the maximum signal voltage that the DAC can deliver.
By adjusting the volume, this signal is reduced and adjusted on the potentiometer of the amplifier according to the required volume level.

 

[ninetylol]

Full 2.1 volt signal from a Smsl SU-1 is the maximum signal voltage that the DAC can deliver.
By adjusting the volume, this signal is reduced and adjusted on the potentiometer of the amplifier according to the required volume level.

Thanks that part i understand. It's more a question of if the Aiyima can handle a higher than 1v signal if the potentiometer is not maxed. That way i can use max Dynamic Range from the DAC.

 

[Guddu]

Thanks that part i understand. It's more a question of if the Aiyima can handle a higher than 1v signal if the potentiometer is not maxed. That way i can use max Dynamic Range from the DAC.

It surely can, no problems.
I have run it with topping E50.

 

[Toku]

The input sensitivity of AIYIMA A07 Max is 1V.
This means that when the volume level is set to MAX, the rated maximum output is reached with an input of 1V.
If you input the DAC's 2V output at this time, it will be completely saturated and distorted.
Therefore, reduce the input volume pot to an appropriate value of 1V or less.

 

[Guddu]

The input sensitivity of AIYIMA A07 Max is 1V.
This means that when the volume level is set to MAX, the rated maximum output is reached with an input of 1V.
If you input the DAC's 2V output at this time, it will be completely saturated and distorted.
Therefore, reduce the input volume pot to an appropriate value of 1V or less.

Or don’t go over 50-60% on A07 max volume pot?

 

[ninetylol]

Thats exactly my question and it seems people have different opinions about it too. Safe bet would be to let the DAC output only 1v and lose some DR.

 

[Toku]

On the DAC side, just set the output to full output in FIX mode and reduce the input volume of A07 Max.

 

[ninetylol]

On the DAC side, just set the output to full output in FIX mode and reduce the input volume of A07 Max.

So you mean reduce volume of my WiiM Pro? Thats my question. I can set max volume setting to about 90% which would be -6db ~= 1v max.

But that way the DAC only receives -6db Signal (via optical) and will only output 1v max. So same thing really.

Tldr: I wanted to know if i can send 2v IF A07 MAX potentiometer is not maxed

 

[antcollinet]

Thats exactly my question and it seems people have different opinions about it too. Safe bet would be to let the DAC output only 1v and lose some DR.

Turning the volume down on the amp will be pretty much the same as sending a lower signal from the DAC.

 

[grogi.giant]

It is better to reduce the input level.

While there is no digital stage in the audio path of the Aiyima (digitalisation of oversaturated signal would create massively distorted digital signal), the signal crosses the op-amps. It is possible they would not handle the high input voltage correctly.

 

[antcollinet]

It is better to reduce the input level.

While there is no digital stage in the audio path of the Aiyima (digitalisation of oversaturated signal would create massively distorted digital signal), the signal crosses the op-amps. It is possible they would not handle the high input voltage correctly.

Very unlikely. There will be a maximum voltage for the input based on the supply voltage for the inptut circuit (whether that is op amp or not).

However it won't be lower than 2V since that would render the amp incompatible with a lot of sources - including pretty much all CD players, and most DACs without volume control. It will most likely be significantly higher, probably closer to 10V than 2V.

On the other hand by maximising the output of the source, you also maximise the SNR, and by turning down the volume on the input to the amp, you also turn down the incoming noise, AND the noise of the amp input stage.

So best noise performance is with maximum input to the amp - though probably inaudibly so in most cases.

 

[T&T]

Finally my 07Max arrived, have 63v caps and the power supply 48v have ferrite core, which my Fosi V3 doesn't have.
So rolling opamp lme49860 meeh, sparkos ss3602 and Muses02 very similar, unexpected old opa cans opamps single made to dual, sorry I will not disclose the number since there are scared...using geshelli akm4499 with 1 sparkos ss3602 this 07Max punches and strikes the sound like a samurai sword, quit fast, low with extensions and layers, same go with hight...bye bye V3

 

[Toku]

So you mean reduce volume of my WiiM Pro? Thats my question. I can set max volume setting to about 90% which would be -6db ~= 1v max.

But that way the DAC only receives -6db Signal (via optical) and will only output 1v max. So same thing really.

Tldr: I wanted to know if i can send 2v IF A07 MAX potentiometer is not maxed

All you have to do is connect the WiiM Pro to the A07 Max at maximum output and adjust the volume of the A07 Max to the required volume. This is a very common connection.
The A07 Max's input sensitivity of 1V does not mean that higher voltages cannot be input. General 2V signals can also be input without problems. In that case, just lower the A07 Max's volume to the appropriate speaker output.

 

[Guddu]

Finally my 07Max arrived, have 63v caps and the power supply 48v have ferrite core, which my Fosi V3 doesn't have.

Did you buy it on Amazon?

 

[T&T]

Did you buy it on Amazon?

No...Aliexpress take over a month

 

[Moth]

Yeah, cheap pots, or lack of qc /testing on decent pots suck. Be nice to have at lease a switch to bypass it (but adds expense). I doubt it’s worth making a separate pot-less version from the manufacturers pov.

audibility of the imbalance depends on overall db levels as the imbalance looks more or less consistent throughout the range. But both the consistency and that channels don’t at least converge closer at max vol in that graph makes me wonder if the imbalance is really from the pot or from someplace else. i guess it’s more likely if it’s a linear pot. But I wonder if there is some mismatch elsewhere. With these gain levels, components at the input stage would need to be tightly matched and the pcb layout well thought out.

Well a vol defeat switch would be nice at least.

I suppose if it really bothers you you could bypass the vol pot by soldering two jumper wires and resistors to the bottom of the pcb. I would guess you would want to put resistors equal to the pot value from wiper to one pin and just a wire from wiper to the other pin. You may be able to use the pot itself instead of resistors as long as you leave it at max and depending on the circuit. should not have to remove the pot itself and thus should be able to keep its power switch function (which I presume uses distinct pins). If the imbalance is still there at least the pot is eliminated as the primary cause.

But that’s a lot of trouble for such a low cost thing. But it would be easy for manufactures to use the same pcb and just use a button or on off knob.


Man, the old fashioned pre amp “balance” pot is looking pretty useful now.

I wonder if the small dimension of the volume pots typically used in these mini amps are partly responsible for the channel imbalance. Do the larger conductive plastic pots like ALPS RK27 etc. allow for better tolerances (larger resistive elements/ contact patches etc.)? It would be an interesting experiment to install a higher quality pot. or resister-based stepped attenuator and measure the imbalance.
I rarely use my balance controls for balancing the stereo image, but do find them really useful for diagnosing issues.