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AIYIMA A70 Mono Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 14 7.7%
  • 2. Not terrible (postman panther)

    Votes: 58 31.7%
  • 3. Fine (happy panther)

    Votes: 96 52.5%
  • 4. Great (golfing panther)

    Votes: 15 8.2%

  • Total voters
    183

amirm

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This is a review and detailed measurements of the AIYIMA A70 Mono TI TPA3255 based class D amplifier. It was sent to me by the company and is on sale for US $116.
AIYIMA A70 MONO hi fi amplifier  monoblock review.jpg

The on/off and input type selectors have good quality feel to them as do the rotary controls. Right one is volume but left one had my scratching my head. Subwoofer frequency? That is something you set once so you don't need front adjustment. Even if you did, what is one in the back that has the same name?
AIYIMA A70 MONO hi fi amplifier  monoblock subwoofer review.jpg

As is, measurements showed that neither made a difference in frequency response of the speaker output. If you however toggle a switch underneath, the front control at least becomes active, setting the high frequency roll off. I could not figure out what the back control did. Reading the instructions didn't help but my conclusion was that the switch turns the amplifier into one that drives passive subwoofer (woofer and no amp). Passive subs have fallen out of favor in US at least for more than two decades. You can get ultra low cost subs that are active. AIYIMA has seemed to gone to great lengths to implement such a functionality with dedicated front and back controls. It is quite puzzling to me. Hopefully you all didn't talk them into this! :)

Nice to see trigger input so amp can be woken up by the source having the same output. And inclusion of extra gain for RCA solves the battle of what the gain should be by default. I like the default of it being off. But some want higher gain (which brings with it more noise and potentially channel imbalance).

I forgot to take a picture of the power supply but it is GaN based, 48 volt @ 5 amp for total of 240 watts in a relatively compact package. In use neither the power supply, or the case (top or bottom) warmed up let alone get hot. Either thermal management is very good or hot stuff inside care isolated from the case.

Note that there is another AIYIMA A70 amplifier (without mono). As with that unit, the mono version here implements post-filter feedback (PFFB) so should have high level of isolation from load/speaker dependency compared to units without. We will measure this.

AIYIMA A70 Mono Measurements
Let's start with XLR input at max volume:
AIYIMA A70 MONO hi fi amplifier  measurement.png


Distortion is at inaudible -110 dB so noise dominates SINAD at 94 dB, placing the A70 mono at the top of the "competent" group of amplifier we have tested:

Best class D amplifier Review.png

Best class D amplifier TI chip  Review.png


RCA input is similar despite higher gain:
AIYIMA A70 MONO hi fi amplifier RCA measurement.png


I am happy to see 25 dB gain here as that is what I think companies need to target unless max power is not reached with 2 volt input.

Frequency response test shows that PFFB is working, sans a bit of increased output impedance:
AIYIMA A70 MONO hi fi amplifier frequency response measurement.png

Given that the 4 ohm also peaks at 20 kHz, the 8 ohm peak is now 1 dB higher than mid frequencies which may be audible to some young people.

SNR is excellent and matches spec fully:
AIYIMA A70 MONO hi fi amplifier SNR measurement.png


I was surprised by the increasing intermodulation distortion in low frequencies in multitone test:
AIYIMA A70 MONO hi fi amplifier Multitone  measurement.png

It is not something I have seen in other implementations. Fortunately our hearing threshold is pretty high at lower frequencies so likely not audible. The rise in the same at higher frequencies is typical:
AIYIMA A70 MONO hi fi amplifier 19 20 kHz intermodulation distortion  measurement.png


Let's measure available power:
AIYIMA A70 MONO hi fi amplifier power into 4 ohm measurement.png

AIYIMA A70 MONO hi fi amplifier power into max and peak 4 ohm measurement.png

AIYIMA A70 MONO hi fi amplifier power into 8 ohm measurement.png


Sweeping at different frequencies we see the jump in distortion at lower end of the spectrum (20 Hz):
AIYIMA A70 MONO hi fi amplifier power into 4 ohm vs frequency distortion measurement.png

On positive front the curves are much smoother and don't rise as much as some other implementations.

Power is nicely maintained across full audible spectrum (with a degree of error):
AIYIMA A70 MONO hi fi amplifier FCC power into 4 ohm measurement.png


I went to test the amp with my Loadbox reactive load but sadly, found the load box not communicating with the PC anymore. :(

Here is the impressive warm up performance:
AIYIMA A70 MONO hi fi amplifier warm up measurement.png


I didn't take a thermal image because as I noted in the intro, the amp and its supply were at room temperature more or less.

Conclusions
AIYIMA A70 MONO amplifier brings highly competent performance to the table with performance that beats majority of amplifiers I have tested. Yet it costs so little. Having balanced input, selectable gain for RCA and trigger are much appreciated. I am at a loss as to what the subwoofer features are about but fortunately, they are disabled using a switch. To be clear, what we/I want is to roll off the main output and have an unmodified output for sub. The sub will have its own filtering. It is the mains that needs filtering.

I am going to recommend the AIYIMA A70 Mono amplifier.
-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
Chipset: TPA3255+NE5532
Replaceable op-amp chips: RT3609SM, OPA2604, OPA2134, LM4562, JRC5532, OP275GSZ, OPA1612 and so on.
Distortion: 0.001%
xlr/rca SNR: ≥ 116 dB
xlr/rca SNR: 96 dB
Frequency Response: 20Hz-20KHz (±0.5dB)
RCA input sensitivity: low gain 2Vrms(26 dB)/high gain 1Vrms(32 dB)
XLR input sensitivity:4Vrms(19 dB)
Speaker Impedance:2-8Ω
Maximum Output Power: 300W (@4Ω) 48V5A
Input Mode: RCA+XLR
Supported devices: decoder, bilevel preamp, computer, CD, cell phone, MP3, etc.
SUB output sensitivity: 2V
Output Mode: 1.0 passive speaker/0.1 subwoofer + active low-pass
Working power supply: 24-48V
Package Size: 126.5*154.5*42mm
Product net weight:900g
 
This is a review and detailed measurements of the AIYIMA A70 Mono TI TPA3255 based class D amplifier. It was sent to me by the company and is on sale for US $116.
View attachment 400113
The on/off and input type selectors have good quality feel to them as do the rotary controls. Right one is volume but left one had my scratching my head. Subwoofer frequency? That is something you set once so you don't need front adjustment. Even if you did, what is one in the back that has the same name?
View attachment 400114
As is, measurements showed that neither made a difference in frequency response of the speaker output. If you however toggle a switch underneath, the front control at least becomes active, setting the high frequency roll off. I could not figure out what the back control did. Reading the instructions didn't help but my conclusion was that the switch turns the amplifier into one that drives passive subwoofer (woofer and no amp). Passive subs have fallen out of favor in US at least for more than two decades. You can get ultra low cost subs that are active. AIYIMA has seemed to gone to great lengths to implement such a functionality with dedicated front and back controls. It is quite puzzling to me. Hopefully you all didn't talk them into this! :)

Nice to see trigger input so amp can be woken up by the source having the same output. And inclusion of extra gain for RCA solves the battle of what the gain should be by default. I like the default of it being off. But some want higher gain (which brings with it more noise and potentially channel imbalance).

I forgot to take a picture of the power supply but it is GaN based, 48 volt @ 5 amp for total of 240 watts in a relatively compact package. In use neither the power supply, or the case (top or bottom) warmed up let alone get hot. Either thermal management is very good or hot stuff inside care isolated from the case.

Note that there is another AIYIMA A70 amplifier (without mono). As with that unit, the mono version here implements post-filter feedback (PFFB) so should have high level of isolation from load/speaker dependency compared to units without. We will measure this.

AIYIMA A70 Mono Measurements
Let's start with XLR input at max volume:
View attachment 400116

Distortion is at inaudible -110 dB so noise dominates SINAD at 94 dB, placing the A70 mono at the top of the "competent" group of amplifier we have tested:

View attachment 400118
View attachment 400119

RCA input is similar despite higher gain:
View attachment 400120

I am happy to see 25 dB gain here as that is what I think companies need to target unless max power is not reached with 2 volt input.

Frequency response test shows that PFFB is working, sans a bit of increased output impedance:
View attachment 400123
Given that the 4 ohm also peaks at 20 kHz, the 8 ohm peak is now 1 dB higher than mid frequencies which may be audible to some young people.

SNR is excellent and matches spec fully:
View attachment 400124

I was surprised by the increasing intermodulation distortion in low frequencies in multitone test:
View attachment 400125
It is not something I have seen in other implementations. Fortunately our hearing threshold is pretty high at lower frequencies so likely not audible. The rise in the same at higher frequencies is typical:
View attachment 400126

Let's measure available power:
View attachment 400127
View attachment 400128
View attachment 400129

Sweeping at different frequencies we see the jump in distortion at lower end of the spectrum (20 Hz):
View attachment 400130
On positive front the curves are much smoother and don't rise as much as some other implementations.

Power is nicely maintained across full audible spectrum (with a degree of error):
View attachment 400132

I went to test the amp with my Loadbox reactive load but sadly, found the load box not communicating with the PC anymore. :(

Here is the impressive warm up performance:
View attachment 400133

I didn't take a thermal image because as I noted in the intro, the amp and its supply were at room temperature more or less.

Conclusions
AIYIMA A70 MONO amplifier brings highly competent performance to the table with performance that beats majority of amplifiers I have tested. Yet it costs so little. Having balanced input, selectable gain for RCA and trigger are much appreciated. I am at a loss as to what the subwoofer features are about but fortunately, they are disabled using a switch. To be clear, what we/I want is to roll off the main output and have an unmodified output for sub. The sub will have its own filtering. It is the mains that needs filtering.

I am going to recommend the AIYIMA A70 Mono amplifier.
-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Thanks for the review @amirm.
Did you test RCA with its +6dB gain or without?

P.E. User Impressions & Owner’s thread HERE:
 
Last edited by a moderator:
Pretty good performance for the money imo but I’m personally not a fan of the overall aesthetics. You’re going to be seeing too many of those yellow knobs at the same time should you decide to go 5.1 with those. Even for 2.x they are unwelcome, as I would think that the (volume) knobs will be practically useless due to the necessity to level match the channels somehow. Thanks for the review, @amirm!
 
Pretty good performance for the money imo but I’m personally not a fan of the overall aesthetics.

And what a pity that is, regarding aesthetics.

Units like that one seem to try to attract people who would be proud to say they don’t even know how to spell that word properly.
 
Pretty good performance for the money imo but I’m personally not a fan of the overall aesthetics. You’re going to be seeing too many of those yellow knobs at the same time should you decide to go 5.1 with those. Even for 2.x they are unwelcome, as I would think that the (volume) knobs will be practically useless due to the necessity to level match the channels somehow. Thanks for the review, @amirm!
Take out the yellow knob you don't like, paint it in pink and you're done, don't forget the fact at this moment the amp is more panther compliant.
 
Take out the yellow knob you don't like, paint it in pink and you're done, don't forget the fact at this moment the amp is more panther compliant.
or just put black (or another color) knobs of your choice.
 
Just about every powered sub has a low pass which rolls off the sub anywhere for 40-160 hz usually with a Linkwitz (24 db octave) or a Butterworth (12 db octave) filter. It's the other half, the high pass, which set the lowest frequency the mains can play and rolls off all frequencies below it, that almost all subs lack. That's why people need things like a miniDSP as standalone electronic crossover, or else employ software based crossovers, like Ekio or JRiver: to get both legs of the crossover filter. Unfortunately, I haven't seen one of these chip amp boxes that offers a complete filter or that supplies what's lacking on the sub. To do that it would need to pass the unfiltered signal to the sub to employ its low pass while rolling off the mains with a high pass. The only integrated amp I've ever seen that does this correctly (by supplying both legs of the filter) is the Parasound Halo from a few years back. It also had a 160 wpc amp section, a DAC, a headphone amp, and a phono preamp for both MM and MC. By today standards its measurables were pretty mediocre, but it was a true one box solution for stereo playback.
 
Just about every powered sub has a low pass which rolls off the sub anywhere for 40-160 hz usually with a Linkwitz (24 db octave) or a Butterworth (12 db octave) filter. It's the other half, the high pass, which set the lowest frequency the mains can play and rolls off all frequencies below it, that almost all subs lack. That's why people need things like a miniDSP as standalone electronic crossover, or else employ software based crossovers, like Ekio or JRiver: to get both legs of the crossover filter. Unfortunately, I haven't seen one of these chip amp boxes that offers a complete filter or that supplies what's lacking on the sub. To do that it would need to pass the unfiltered signal to the sub to employ its low pass while rolling off the mains with a high pass. The only integrated amp I've ever seen that does this correctly (by supplying both legs of the filter) is the Parasound Halo from a few years back. It also had a 160 wpc amp section, a DAC, a headphone amp, and a phono preamp for both MM and MC. By today standards its measurables were pretty mediocre, but it was a true one box solution for stereo playback.
The RSL iA255.1 has main+sub (3.5mm) outputs with an optional 90Hz HPF switch on the mains. Not an adjustable HPF, but more than what most are offering.
 
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I'll leave it to Aiyima to determine whether there's a market for a passive subwoofer amplifier. They probably want to differentiate from Fosi in this regard, but yeah I wonder how many they'll sell for that purpose.

I like power amps with volume control, if only to set the max level. It might be paranoia but I don't trust digital volume to not go full max. Nice to have a potentiometer in the signal path.

With less power, more peaking, and higher distortion, I imagine more people will go with the Fosi monos for only a little more money. But this is a pretty nice piece of kit.
 
I went to test the amp with my Loadbox reactive load but sadly, found the load box not communicating with the PC anymore.

Windows updates probably killed the communications.
 
I really don't understand the reason for the sub frequency knob on the front. As noted in the review, most subs today are active and have frequency controls themselves. I do like the low price, and the fact that it's a GaN power supply. However, since I don't have a sub, if I wanted to go the monoblock route, the Fosi mono amps would be my goto.
 
Just about every powered sub has a low pass which rolls off the sub anywhere for 40-160 hz usually with a Linkwitz (24 db octave) or a Butterworth (12 db octave) filter. It's the other half, the high pass, which set the lowest frequency the mains can play and rolls off all frequencies below it, that almost all subs lack. That's why people need things like a miniDSP as standalone electronic crossover, or else employ software based crossovers, like Ekio or JRiver: to get both legs of the crossover filter. Unfortunately, I haven't seen one of these chip amp boxes that offers a complete filter or that supplies what's lacking on the sub. To do that it would need to pass the unfiltered signal to the sub to employ its low pass while rolling off the mains with a high pass. The only integrated amp I've ever seen that does this correctly (by supplying both legs of the filter) is the Parasound Halo from a few years back. It also had a 160 wpc amp section, a DAC, a headphone amp, and a phono preamp for both MM and MC. By today standards its measurables were pretty mediocre, but it was a true one box solution for stereo playback.
I built my own subs, hence each gets an NAD2200 bridged mono. The filtering is done upon the signal exiting the Apt/Holman Preamp before the amplifiers.
 
Windows updates probably killed the communications.
That's what I am hoping although I did test it also on my laptop running Windows 11 and it too had the same problem (desktop running Windows 10). The unit has diagnostics for the Com port and it says that is fine. It just isn't able to then actually send a message to the Loadbox. Have email into designer, hoping he has a solution.
 
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