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Aiyima A07 Max Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 32 14.2%
  • 2. Not terrible (postman panther)

    Votes: 113 50.2%
  • 3. Fine (happy panther)

    Votes: 65 28.9%
  • 4. Great (golfing panther)

    Votes: 15 6.7%

  • Total voters
    225

space_duck

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Just got my Fosi BT30D in the mail, and it turns out the amp has a mute "feature": if it detects no audio for a few seconds it will mute itself, and unmuting it takes half a second. This has already happened inbetween songs on an album, thus cutting off the start of the next song. Would be a great feature if unmuting was instant but as it is it's unacceptable.
Can anyone confirm whether or not the Aiyima A07 Max has the same design flaw? I have one in the mail already and really hope it doesn't.
 

musicforcities

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This review makes me confident I will enjoy the A07 Max I have in the mail. In any other situation the possible channel imbalance would likely bother me, but that can be fixed in my AVR if necessary. The load dependency is a bigger deal, I hope it's not an issue with my speakers.
I'm curious, how hard would it be to replace the volume pot with a better one? Is that just a simple solder job?

A simple solution to this could be a volume pot bypass switch, shouldn't add a significant cost and would please everyone.
Yes that would be a nice touch. To keeps costs down they could use of a volume pot that has a push switch incorporated into it that bypasses it. Though that may be dangerously easy to accidentally activate.

Turning the vol pot to max effectively bypasses it in any case and it would have to be a very bad pot indeed if it caused channel imbalance at max. Some channel imbalance at low volumes is almost always present in analogue volume potentiometers due to the nature of them because at low volumes the signal is passing through much more of the resistive material which itself has some degree of variation, and our ears can hear small level differences at low volumes whereas at higher volumes any channel imbalance db becomes a far smaller fraction of the total db. I

It is impossible to know if the specific unit tested happens to have pot outside acceptable margins of variation. If i got one this bad, I would return it for a different unit if I intended to use the volume control.

Yes I suppose you could solder in a new vol. pot of the same total resistance, pinout, lead spacing etc. it’s often pretty easy to damage the tiny traces when desoldering a pot however.

It’s likelly makes more sense to just adjust the level at thr digital source or preamp stage if you can (a dac with digital vol control, a full preamp, avr, dsp, computer volume etc).

If you need or want to control volume in the analog domain, You could get something like the $50 Schiit Sys, a passive preamp with a volume pot and 2 selectable inputs. Presumably the pot used is more consistent.

Or get a passive analogue pre with a better volume control type, like a resistor based attenuator, etc. those can be great assuming the resistors are precisely matched. or a relay- resistor attenuator if you want remote control and don’t mind the relays clicking when you change the level. But those are many times the price of the amp itself unless you get a generic one from the bay or aliexpress etc. . Though matching resistor values is pretty easy these days.

But seriously, assuming you have a digital source for the price of the aiyma, just set the vol ar max and control the volume in the digital domain. Or if that leaves you with too little usable range of levels in the digital (as it did for me with the a07 and the JBL studio 520s) set the aiyma at something likehalf volume and see if any channel imbalance is noticeable or measurably significant relative to your typical listening levels. That way you can strike a “balance” (sorry) between bit loss of digital attenuation and the vicissitudes of analogue volume.
 
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Guddu

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Just got my Fosi BT30D in the mail, and it turns out the amp has a mute "feature": if it detects no audio for a few seconds it will mute itself, and unmuting it takes half a second. This has already happened inbetween songs on an album, thus cutting off the start of the next song. Would be a great feature if unmuting was instant but as it is it's unacceptable.
Can anyone confirm whether or not the Aiyima A07 Max has the same design flaw? I have one in the mail already and really hope it doesn't.
Aiyima A07 Pro, Aiyima A07 Max and Fosi ZA3 do not do auto mute or anything like that.
 
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musicforcities

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Hmm... As an owner of multiple such ebay amps I have no doubts about the amps' longevity. Of course the usual caveat of "a bad product still lasts long for 90% of owners" applies.

Plus it's usually the power adapter that gives out first, without exception.
There are a few good things about external power supplies: easy to replace, you can hide them awa, you can change them if you needs change, keeps mains level ac out of the same enclosure.

Heck, audiophile brands like NAIM used to make a big deal out of their external power supplies…and charged a ton for the luxury.

Aiyma and fossi should make a ps in a case with the same design as the main unit and charge the same price as the amp and reg power supply just for the “audiophilel” upgraded ps. Lol
 
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Baltima

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The way I read it, if you connect two bass drivers to the crossover it is 2ohms, one bass driver only then 4 ohms. I presume the bass drivers are rated at 4ohms nominally and the crossover can connect two of these drivers in parallel which results in 2ohms nominal impedance. But depending on the crossover design, adding the mid and tweeter drives may bring the total impedance up to 4 nominally if all of them are driven by the same amp channel (not biamped). But I can’t be sure based on the info you provided.

More questions should be directed to a sub forum on the page having to do with diy and or diyaudio.com.
Correct
1x Bass = 4 Ohm - Mid and High = 4 Ohm
2x Bass = 2 Ohm - Mid and High = 4 Ohm

This is a Audio System Set, with same Crossoversystem.
2x Bass = 2 Ohm - Tweeter = 4 Ohm

The Tweeter in this Set: HS 25 EVO2, a 4 Ohm Tweeter

Input with 2 Ohm Amplifier
 

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musicforcities

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Correct
1x Bass = 4 Ohm - Mid and High = 4 Ohm
2x Bass = 2 Ohm - Mid and High = 4 Ohm

This is a Audio System Set, with same Crossoversystem.
2x Bass = 2 Ohm - Tweeter = 4 Ohm

The Tweeter in this Set: HS 25 EVO2, a 4 Ohm Tweeter

Input with 2 Ohm Amplifier

Dude, you sort of hijacked this thread. Start a new one in a sub-forum relevant to your topic and ping me in it and I’ll try to help there.


Anyway, Ayima A07 max good. If they continue to follow Apple’s naming conventions for iPhones, I guess next year they will release the A07 PRO MAX, and it will have the power of the 3E AUDIO board that was recently reviewed. lol.
 

grogi.giant

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Anyway, Ayima A07 max good. If they continue to follow Apple’s naming conventions for iPhones, I guess next year they will release the A07 PRO MAX, and it will have the power of the 3E AUDIO board that was recently reviewed. lol.

Well, check Aiyima D325x...
 

Jeromeof

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OK since I have 2 A07MAX's I thought I would check out if either of mine had a similar channel imbalance to @amirm. So one of mine was an early pre-release (possible the same batch as Amir's the other one I bought subsequently on Amazon.de).

The following graph has 4 measurements - 2 with the left and right on one A07MAX and the other 2 with the left and right on the second A07MAX - to do this I had everything the same and merely swapped the binding posts - so its the same speaker / microphone / laptop and amp in the same position (I removed all other components in my setup for this test).


A07MAX-ChannelBalance.png
 

Joe Smith

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OK since I have 2 A07MAX's I thought I would check out if either of mine had a similar channel imbalance to @amirm. So one of mine was an early pre-release (possible the same batch as Amir's the other one I bought subsequently on Amazon.de).

The following graph has 4 measurements - 2 with the left and right on one A07MAX and the other 2 with the left and right on the second A07MAX - to do this I had everything the same and merely swapped the binding posts - so its the same speaker / microphone / laptop and amp in the same position (I removed all other components in my setup for this test).


View attachment 334742
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.)
 

MCH

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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.)
You mean the 3db difference between amps is due to the volume pots? Or do you consider that there is still an unacceptable imbalance from L to R of these two units? They seem quite ok to me.
edit: well, maybe unit 1 has half a db stronger L in some frequencies?
 
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Jeromeof

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You mean the 3db difference between amps is due to the volume pots? Or do you consider that there is still an unacceptable imbalance from L to R of these two units? They seem quite ok to me.
edit: well, maybe unit 1 has half a db stronger L in some frequencies?
Yes I thought they were fine - the two a07max were not level matched for this. Sorry i should have made it clear so the 2nd a07max was just at a different level but both left / right measurements on each were very well matched I think.

And yes I thought the 2nd was roughly 0.5db different in some frequencies ( and I am pretty sure that was the prerelease model)
 

musicforcities

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some variation between different pots is normal and unavoidable (ie different examples of the same model of potentiometer and/or on different amps). Some channel imbalance in a single stereo pot is also almost unavoidable for the same reason, though a decent manufacturer will match the two channels as closely as possible and try to get it below noticeable thresholds. The resistive traces used have some inherent variation (just as resistors can have a given range +\- its spec value. Question is whether either variation exceeds the pot manufacturer and model’s acceptable range.

Audio taper pots are especially susceptible to pot to pot variation and single pot channel imbalance due to fact that the resistive traces are manufactured to have logarithmically changing resistances along its length. That is due to how we biologically hear db levels: at low volumes we hear difference in db much more acutely than at higher dbs. So an audio taper pot compensates for that by changing the incremental of resistance for each mm of rotation. We hear that a linear increase in volume level, but to achieve that resistance of the trace per a unit of wiper travel has to increase along the total travel. A linear pot does not do this. For example if a linear pot rated at 100ohms has 100 degrees of total rotation, each degree of rotation equals 1ohm of resistance each (ideally). Set it at 25 degrees it has 25ohm, 75 degrees 75 ohms. But in an “audio taper” pot of 100ohm and 100 degrees of total rotation, each degree of rotation will have different ohm values each.

It is far easier to make a consistent linear pot trace that has the same ohms along its length than it is to make a consistent audio taper pot traces (that varies resistance along its length). Moreover, variations are far more problematic at the lower end of the volume range both because any manufacturing variation of the traces themselves are more impactful because the lower volume levels means more resistance and thus the signal is passing through more of the trace that inherently is prone to variations and because, for our example audio taper pot above, a 10% variation of the left and right channels means a range of +/-9 ohms with the volume set at “1” (90ohms nominal) but only +/-1 ohm when set at 9 out of 10 (10 ohms) . Of course this is compounded by the fact that for same reason we need audio tapered pots means that variations we perceive variation much better at low levels. So making stereo audio taper pot with two different traces that match values for every mm of travel (degree of rotation) or are at least below audibility is far more challenging than making a linear one. I think that is one reason these inexpensive amps use linear volume pots so often—they are cheaper to buy and far easier on quality control.

This is one reason why, btw, other well implemented methods of attenuation are inherently preferable, from digital to stepped attenuators using discrete resistors for each step (relay driven or manual).
 

T&T

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I think, I get scammed at Aliexpress with Aiyima a07 max, black friday sales 87.21 with 48v, the order was placed November 27, glad that I paid with PayPal, and open a case at Aliexpress which communication was a painful thing using Google web.
 

grogi.giant

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I think, I get scammed at Aliexpress with Aiyima a07 max, black friday sales 87.21 with 48v, the order was placed November 27, glad that I paid with PayPal, and open a case at Aliexpress which communication was a painful thing using Google web.

Three weeks for delivery from China around black Friday? THat's not frequent, but absolutely possible.

I think you simply got impatient, not scammed.
 
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Joe Smith

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Yes I thought they were fine - the two a07max were not level matched for this. Sorry i should have made it clear so the 2nd a07max was just at a different level but both left / right measurements on each were very well matched I think.

And yes I thought the 2nd was roughly 0.5db different in some frequencies ( and I am pretty sure that was the prerelease model)
Oh, great! I was interpreting the graph as showing a 3-4 dB difference across the frequency range between L and R. I think a .5 - 1 dB difference in a product at this price point is just fine.
 

T&T

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Three weeks for delivery from China around black Friday? THat's not frequent, but absolutely possible.

I think you simply are impatient, not scammed.
No tracking number provided just the promised of delivery by December 18, I contacted Aiyima they can not find my order and I open a case at Aliexpress, waiting for resolution will take 3 to 5 days, anyway PayPal is also in the middle, the good... maybe 07 Max will be not better that Fosi V3 which I already got it.
Thanks
 

Toku

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I think, I get scammed at Aliexpress with Aiyima a07 max, black friday sales 87.21 with 48v, the order was placed November 27, glad that I paid with PayPal, and open a case at Aliexpress which communication was a painful thing using Google web.
Be careful when shopping on November 11th, Singles' Day, or Black Friday. Delivery often takes two to three times as long as usual. Also, there are many problems with shipping during this period.
I previously ordered an SMSL product from Shenzhen Audio, but the tracking was stopped midway through China and the product did not arrive even after 2 months. In response, Shenzhen Audio refused, saying that the item was shipped reliably and that they would not compensate for any shipping accidents. Aliexpress also intervened, but to no avail.

During bargain sale periods, tracking is often not possible until a week or more has passed since the tracking number was issued, so you will need to wait a little more patiently than usual. Moreover, it is even more so since the purchase is from a faraway country with a completely different social system.
 

space_duck

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I previously ordered an SMSL product from Shenzhen Audio, but the tracking was stopped midway through China and the product did not arrive even after 2 months. In response, Shenzhen Audio refused, saying that the item was shipped reliably and that they would not compensate for any shipping accidents. Aliexpress also intervened, but to no avail.
Thank you for sharing this, I will make sure to avoid Shenzhen Audio in the future.
 

G-Can

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Just got my Fosi BT30D in the mail, and it turns out the amp has a mute "feature": if it detects no audio for a few seconds it will mute itself, and unmuting it takes half a second. This has already happened inbetween songs on an album, thus cutting off the start of the next song. Would be a great feature if unmuting was instant but as it is it's unacceptable.
Can anyone confirm whether or not the Aiyima A07 Max has the same design flaw? I have one in the mail already and really hope it doesn't.
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.
 
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