Aiyima A07 Max Amplifier Review

[MCH]

Sorry if I misunderstood, I wasn't following, but if you refer to 1Vpp at the speakers terminal with no signal input at the switching frequency, I can confirm this.

 

[antcollinet]

And how such simplest value can be measured incorrectly? In what way error can be introduced?

Well in order to measure the output of the amp you need to be using a differential probe for your scope. Are you? If you are, what is the channel balance of the probe?

Ears definietly are Sensitive to quality of generated waveform,

Sure they are - but only when that quality exists in the frequency band to which they are sensitive. They are not sensitve to any frequencies at any level outside that bandwidth - especially 4 and a half octaves outside. The bio-meachanics of the ear literally has nothing to respond to them with. Even if the speaker were able to create a sound wave at that frequency - which they cannot.

But look - I've said that three times now in different ways, and you are not getting it. I suggest we stop. I will at least.

 

[antcollinet]

Sorry if I misunderstood, I wasn't following, but if you refer to 1Vpp at the speakers terminal with no signal input at the switching frequency, I can confirm this.
View attachment 419911

Again, measured with a differential probe?

And 1V p-p is not 1Vrms, it is 350mV rms.

 

[NTK]

At idle (no input), for a class d amp, the duty cycle of the PDM output is 50%, i.e. a regular square wave at the switching frequency (see the PDM waveform near the zero crossings on the sine wave). Therefore, the output before the LC filter is this square wave alternating between the rail voltages.

Below is the output noise spectrum of the Topping PA5. (I spent a few minutes looking but failed to find a similar plot for a TPA 3255 amp). The TPA 3255 amp switching frequency was at ~450 kHz in the scope trace, so the output filter attenuation could be several dB less at than the 38 dB of the PA5. When we have a 48 VDC rail in BTL mode, a switching noise Vpp of ~1 V should be more or less typical. The pertinent question is what the speaker impedance is at the amp switching frequency, and that will tell us how much current and power go the speaker.

 

[LDvo]

Some thoughts:
I am using now two Aiyima A07 Max in dual mono as stereo amp
- so far so good (with stock power supply, enough for me for now for very reasonable price).

I hope Aiyima is monitoring this chat - thanks for such a good product and I'd like to suggest
- A07 Max has sliding switch on the bottom to change stereo and mono mode.
When you use this amp in mono mode - second pair of speaker terminals cannot be used - wasted.

It would be nice if this Amp also could have additional switch
next to stereo/mono one: only if Amp in mono - use 1st speaker or use 2nd speaker.
In this case Amp in mono mode will be able to use all available speaker terminals
to handle 2 speaker sets, similar to full size stereo amp.

 

[dr_mick51]

Some thoughts:
I am using now two Aiyima A07 Max in dual mono as stereo amp
- so far so good (with stock power supply, enough for me for now for very reasonable price).

I hope Aiyima is monitoring this chat - thanks for such a good product and I'd like to suggest
- A07 Max has sliding switch on the bottom to change stereo and mono mode.
When you use this amp in mono mode - second pair of speaker terminals cannot be used - wasted.

It would be nice if this Amp also could have additional switch
next to stereo/mono one: only if Amp in mono - use 1st speaker or use 2nd speaker.
In this case Amp in mono mode will be able to use all available speaker terminals
to handle 2 speaker sets, similar to full size stereo amp.

Well, you can't. First, in mono mode the amplifier will use both positive terminals from both channels Why? Because it is using both channels as a one.
Do you want both channels outputing the same signal(left or right) to a 2 different speakers?. Are these speakers identical or with same sensitivity? If not one might sound louder than the other.
Let me tell a story. One day I was dissassembling the amp and inspecting what was inside, and by mistake I moved the mono/stereo to mono without knowing. After reassembling and connecting my RCA and speakers cables I noticed my speakers were playing really weird, I lost all the imaging and sounstage, i thought I broke the amp or something. I was getting mono from both speakers. Until I realized I moved the switch.
So, you can try exactly that, use mono mode, connect you RCA cable into the left channel on both amplifiers and use both speaker outputs from each amp for left and they other for right.
Tecnically this is not a true mono mode, because for a true mono you need to use both channels together to feed one speaker.
I really don't understand why you would like to do something like this in first place.

 

[LDvo]

Well, you can't. First, in mono mode the amplifier will use both positive terminals from both channels Why? Because it is using both channels as a one.
Do you want both channels outputing the same signal(left or right) to a 2 different speakers?. Are these speakers identical or with same sensitivity? If not one might sound louder than the other.
Let me tell a story. One day I was dissassembling the amp and inspecting what was inside, and by mistake I moved the mono/stereo to mono without knowing. After reassembling and connecting my RCA and speakers cables I noticed my speakers were playing really weird, I lost all the imaging and sounstage, i thought I broke the amp or something. I was getting mono from both speakers. Until I realized I moved the switch.
So, you can try exactly that, use mono mode, connect you RCA cable into the left channel on both amplifiers and use both speaker outputs from each amp for left and they other for right.
Tecnically this is not a true mono mode, because for a true mono you need to use both channels together to feed one speaker.
I really don't understand why you would like to do something like this in first place.

I really don't understand why you would like to do something like this in first place.

- Why full size stereo amp usually has terminals to handle 2 sets of speakers?
Why can't i have the same in case of A07 Max in dual mono (unless it is technically impossible)?

 

[Foxxy]

Looked for a good cheap small class D amp for my dad who is a bit hard of hearing. And the gain together with max power on his old amp wasn't giving him good levels on some stations. And yeah, it's the trusty Dayton DTA-1, so not a lot of real power. So I found this, measurements are okay, price is good, Amir even liked them on his Revel Salon, let's go.

Got it, hooked it up to my own system with two UniFi Reference floorstanders which so far have been powered by an IcePower 125ASX2. Thought it would sound about the same. Nope, there is a lot more resolution on tap across the whole frequency range. Plus, this drives much harder and bodily dynamics than the IcePower. With the IcePower, I heard the outlines of the drums cleanly but there was no body to the whole event.
Now, it's of course also the speakers, my Klipsch RP600m-II had no problem doing that with the IcePower amp. But now I also have some of it on my Elacs. Very impressed.
That said, I'll have to get used to this clarity a bit. Not sure if treble is 100% smooth. Could of course also be the tweeter, there is only so much you can get a non dimple, non ring cloth dome.

This is some amazing 120€ amplifier. Almost tempted to keep it so I can compare when I get a Hypex nCore later this year.
And really wasn't prepared for the greater palpability and texture in the bass. Why is this there? Maybe different output impedance? So yeah, thanks to Amir for hooking it up to his Revel and making me pull the trigger