[jeromeoflaherty]

I thought I would share some details on the latest Amplifier from Aiyima the A07 MAX. But first a little history of the reasons why this amplifier is special

A brief history of TPA3255 amplifiers​

The Aiyima A07 was the first "cheap" class D amplifier recognised by the audio community as "audiophile" quality yet at a nice price for those starting off in the hobby of home audio. It provided clean / neutral sound without the noise / "tinny" sound of previous class D amplifiers in the equivalent price range. It was praised by subjective "YouTube" audio reviewers like the CheapAudioMan yet also highly praised by objective reviewers from AudioScienceReview and others for its excellent SINAD / THD+N values (meaning it provided clean audio without distortion at high levels of output with a neutral accross bass, midrange and treble). There were other competitors in this market but Aiyima iterated over the design of the A07 with the A08 and a number of other class D amplifiers adding more features like bluetooth / tone controls etc to the basic TPA3255 design.

But recently one of their competitors (Fosi Audio) went "back to basics" with their design for the Fosi Audio V3 - not adding "features" but using higher quality components, a new orientation of the amplifier board and better cooling to provide a high quality alternative to Aiyima TPA3255 products. So I love competition in the audio industry and I was very interested to see what Aiyima would do in response to this challenge and I am glad to see that the Aiyima A07MAX is a great response to Fosi Audio.

The Aiyima A07MAX:

Comparison of the A07MAX and Fosi Audio V3​

Both amplifiers are effectively very similar (basically both are getting the absolute most you can get out of the TI chipset) so the choose about which is best for you is probably down to what you want for now and how you might want to expand you home audio setup going forward. The advantages of the MAX compared to the Fosi Audio V3:

1. New Design and the Board layout
I think the wider design on the MAX allows allot more space at the back of the Ampflifier - meaning cables are well separated - see photo below. They effectively redesigned the MAX so it's wide instead of deep. See picture below of the base of the MAX:

2. Nicer binding Posts
The “offset” of the binding posts is much better and I think they have much higher quality binding posts than the V3,

3. Mono mode (and the switch)
This is a great option IMO - it shows off the upgradability - i.e. start with 1 A07MAX in stereo, then buy a second one and setup each as a Mono Block Amplifier (with a pre-amp controlling the volume)

The advantages of the V3 compared to the MAX:
1. Volume control on the V3 is more subtle control over lower volumes.
Aiyima have confirmed they are the same analog linear potentiometer as the V3 but the sensitivity of the A07 MAX is twice that of V3, so while the A07MAX volume is nicer than previous Aiyima Amps but IMO the volume on the V3 is slightly nicer and it is very subtle with lower volumes with the Aiyima having more control over larger volumes.

2. Lower THD+N / Higher SINAD value
The Aiyima published THD+N results for A07 MAX are slightly behind the V3 (0.003% for the V3 and 0.007% for the MAX) this translates into SINAD values of -90 for the V3 and -83 for the MAX. Note: these measurements have not been independently confirmed yet but they are inline with the expectation based on previous results.

3. Some may like the vent hole pattern on the top of the V3 - obviously both have the vent holes on the bottom and on the sides but the V3 vents on the top have a nice pattern ( though I do wonder about stacking components with the V3).

The internal layout of the A07MAX looks good and I believe their new design has been optimised for minimising the heat when used for extended periods:

As for powering A07MAX has excellent choices with power supply especially when using it in PBTL Mono mode (in a dual mono-block configuration):

So in summary, so far I think it's a very nice upgrade over previous Aiyima TPA3255 Amplifiers like the V3 and over the Fosi Audio V3.

 

[Scrufboy]

Love this... Thank you. To note for the community, the Fosi V3 also copied over the A07's original design flaws... Users including myself have reported that the unit has channel cross-feed.

Meaning, under certain conditions you can hear left channel audio over the right channel speakers and vice versa. This happens at louder volumes in every use case as some have reported. But even more so when paired with an amplifier that sums the left and right channel for LFE sub out use. Such is the case for users who pair the unit with a Fosi M-03 or an Aiyima A3001 sub amp to power passive subs or control active subs.

The main cause of this is that the "pre-out" of the V3 and the "aux 3.5" of the A07 are just pass-through connections. Basically a Y cable. They are not true pre-outs or even an aux. This also makes it possible to use either the RCA or the 3.5mm for input. Obviously not at the same time though.

This was testest extensively over the past two weeks by myself and others. There are workarounds, but there shouldn't need to be. I am currently in email exchanges with Fosi to address the issue. Incidentally, they did not copy the flaw from these units in their BT20A Pro

Aiyima's A07 Pro release also did not produce this error. I use one of these in my bedside rig now, having removed the V3 due to this error. This unit has a true line out and the 3.5mm socket cannot be used as an input at all.

As for the V3, the issue kind of ruins all their efforts to produce a better sounding amplifier. It is a defunct unit now in my book.

To get back on track and bring some "other related" news to the post. I have purchased 2 of these Aiyima A07 MAX units and I'm looking forward to testing them out. They do have one issue out of the box and that is the use of 50V 2200uf caps. The unit, with a 48V supply REQUIRES 63V 2200uf caps.

To end...

Fosi just put the ZA3 on kickstarter. It is said to have slighty worse measurements to the V3. However it looks like a competitive answer to both the A07 pro and the MAX.
I'll post the board so we can see both together.

Featuring both SE RCA & Balanced XLR inputs, stereo or mono operation, RCA for SUB out. Single volume control.. No BT, No tone controls and like the A07 Pro, 5 swappable opamps.

Things are heating up! My two A07 Max units should arrive within the week. I look forward to everyone's opinions and experiences. I will of course report back. I have the ZA3's coming too.

 

[Scrufboy]

To post a curiosity... The V3 uses a logarithmic volume pot. Not a linear pot. However we see Aiyima claim they use the same pot as the V3 on their MAX unit, yet refer to it as linear. This makes no sense.

 

[jeromeoflaherty]

To post a curiosity... The V3 uses a logarithmic volume pot. Not a linear pot. However we see Aiyima claim they use the same pot as the V3 on their MAX unit, yet refer to it as linear. This makes no sense.

It’s not the same the V3 is more subtle at lower frequencies which is nice

 

[Scrufboy]

It’s not the same the V3 is more subtle at lower frequencies which is nice

Yeah.. I knew this.. I have two V3's. One pot is taper A and the other is taper B. The logarithmic pot of the V3 works more like how our ears hear sound. In design, it is supposed to be subtle until about 2 o'clock on the dial and then it increases at a faster rate as you turn it toward full volume.

My curiosity comes from Aiyima's statement. Not in the pot difference. I follow your post on ASR too.

 

[Scrufboy]

Just got my Aiyima order..

These units have the same problem as the original A07 and the FOSI V3.

They produce crossfeeding of their signals when paired with the company's own subwoofer amplifiers.

The AUX out is nothing more than a simple pass through, like a Y cable. It is not a true line out like their A07 Pro.

Very disappointing. Waiting for FOSI ZA3

 

[D1N0]

I am waiting until someone reviews the ZA3 as a monoblock solution. Want to know where they cut corners.

 

[Scrufboy]

I have two coming through the kickstarter. I have looked at the board. The numbers disappoint me a little though, but I know if you use a cleaner power supply and swap the opamps out, you will be able to improve on those numbers a bit. The LM4562 and OPA2134 have been successfully used to improve the sound a bit while upping the noise rejection in the first round of TPA3255 amps.

You could go all discrete... But for that money, you are entering the realm diminishing returns and just better off buying a better amplifier.

I have a Nord coming, even their value line NC252 MP will have insanely better numbers than those amps will. Regardless, I am intrigued by the prospects of the ZA3. The unit definitely favors the XLR input. Of the 5 opamps.... One is dedicated to the XLR input. 2 to L&R (water that could mean) and 2 to the sub - which seems odd. Almost like the opamps are more of 'let's compete" thing and less of a competent thing. They could have used 2 for input and gain stage of the XLR. 2 for the output... And one for the RCA inputs

 

[shan20nu]

https://photos.app.goo.gl/LbDGwd35vrBXUrAm8
I have got mine yesterday with 46V adapter. First thing I remove the OpAmp and replace with LM 4562. Thats a huge upgrade for this amp. Just stunning sound quality !

 

[ggetzoff]

This needs to be tried with a 6S lipo, that'll sonically blow away any PSU.

 

[johnnyb]

https://photos.app.goo.gl/LbDGwd35vrBXUrAm8
I have got mine yesterday with 46V adapter. First thing I remove the OpAmp and replace with LM 4562. Thats a huge upgrade for this amp. Just stunning sound quality !

I got my V3 a couple days ago too. The original opamps did not last long! I also found removable LM4562's - robbed them from an unused DAC. Went from grainy and kind of bloomy in the bass to a much smoother, even sound. Can't wait to try some more!

 

[JEnglishSmith]

This is a mini-review of the A07 MAX from my "average Joe" perspective. Aiyima was gracious enough to send me a unit for review and evaluation. I found the amplifier to be a lot like the Fosi V3 - apart from the noted Stereo/Mono feature, which I have not made use of.

While I think the Mono capability is an interesting addition, to me it's kind of a halfway step to true small monoblock Class D amps without integrated volume pots. The mono capability would seem to me to be most useful to people with a medium sized listening space with medium to high efficiency speakers who want to use the 48v power supply option to get medium to loud volume levels. You could do this in a smaller room or desktop setup, but why? Even with the 36v power supply I can get to very loud levels in my workroom with my 87db efficient KEFs.

During the past week, I have switched back and forth between the older Aiyima A04 and A07 amps, the Fosi V3, and the new A07 MAX amp, and varied between use of the Fosi 32v 5a power supply and the Aiyima 36v 6a power supply. All gave good sound and satisfactory volume levels. No noticeable power on or power off pops. Using a variety of sources, I did not detect any truly notable differences between the amps. I like that the V3 and MAX amps are vented, and I believe this should help add to the product longevity. This is even more important for users who are making use of the 48v supply to get to higher volume levels. With the 32v and 36v power bricks, none of these amps get very warm to the touch at all. All of these amps can get higher volume than my SMSL AO100 amp, which I like for the dining room (remote and integrated bluetooth) where I don't need high volume levels at all.

I am using the V3 and MAX amps with the supplied 5332 op-amps. I had changed out both of the older Aiyima amps to 4562s.

I like the very clean and simple appearance of the A07 MAX. Aiyima has made a nice case and clearly designed the product to compete with the V3. The lack of top case holes might be a plus for some users as a) it makes it less prone to liquids or other dust entering the case and b) it makes it stackable. But since Aiyima has no matching components, that's not a huge consideration. I especially like that the Stereo/Mono switch is well recessed from the case so it cannot be bumped accidentally. Good design work there.

It's a little thing, but given how close all these amps are, little things matter...IMO the knob is not as nice to use as the Fosi V3. It's just a little bit smaller, and in my sample, it mutes to about the 3rd volume marking. Because the Fosi knob is larger, it's easier to grip and quickly change a volume level over my shoulder, which is how my setup is arranged. If you are looking right at the amp on one's desk or shelf, that's less important - but I still think that Fosi wins the ergonomics award for the knob. It's got a little better control to set a low volume level easily.

Another feature of the A07 MAX is the offset speaker jacks. Yes, they are of higher quality and thickness than the Fosi. They stick out more in the back, and the best way to connect safely is still with banana plugs. The provided jacks don't make connecting with bare wire easier or advisable IMO. So it's kind of a difference that makes no difference, save perhaps for the users with very wide or angle-type plugs - (probably same users who are using the amps as mono units?).

All of these amps do the basic job of amplification for small to medium setups and in a nice way. I think for me personally, the V3 still is the nicest to use and has the most attractive appearance.

I think the next logical step is for one of the Chinese manufacturers to a) solve the noted load dependency issue for frequencies above 10k; b) create an attractive and good-component built true monoblock option (with the power supply in-case with the amplifier) that would compete with the Hypex amps but at a lower cost; c) create a matching solid state preamp for the monoblocks with a high-quality volume control, 2-3 inputs, and a remote.

It's great to have so many good choices right now in these compact amps. I am glad that Aiyima is continuing to develop some solid state, clean, "no frills" units along with their tube and more steampunk looking options. The A07 was the first small amp I'd bought since my decade-old SMSL SA-50s, and it was an improvement, which the A07 MAX takes further still.

 

[D1N0]

Apart from the ZA3 Fosi is also working on a pre-ampless monoblock version. Yet unnamed. Image from someone in the Fosi Facebookgroup. These are three different versions. There isn't a final one yet:​

 

[Scrufboy]

I have all of these TPA3255 amps.. And while they are fun... As soon as my Hypex arrived, I never went back. Looking forward to the ZA3

 

[Sharppain]

I have all of these TPA3255 amps.. And while they are fun... As soon as my Hypex arrived, I never went back. Looking forward to the ZA3

Hi, please, share what Hypex you got. I mean is it a DIY project that you did using an amplifier board or is it a ready device (an amp board in a box). Frankly, I am looking for a fully ready set.