AIYIMA A20 Stereo 2.1 Amplifier Review

[Mark185]

@Mark185 i know of some speakers manufacturers equip packages with fitted plugging foams of certain volume. Dynaudio I know of for sure.

Yes, I am aware of this but their drivers are designed to work in both sealed and ported enclosures. I do not own any of them but in the past, I purchased Dynaudio drivers and built my own speakers with them. The classic Dynaudio 160mm driver had a Q of 0.7 for many years that could work in ported or sealed. It actually worked very well in something called an aperiodic enclosure that had small port(s) with damping material in it. Most drivers for ported designs have Q below 0.5 and when you put them in a sealed enclosure, the -3 dB frequency is up in the 100 Hz range. Dynaudio with a foam plug is very likely an aperiodic design and not a true sealed enclosure and as noted above, their 160mm drivers worked well like that.

Some of these drivers when put in a sealed enclosure, have a Q in the 0.5 range which rolls off in a very mild slope. Q of 0.5 is good from a standpoint of minimal phase shift but the 6" driver will still get fed significant low frequency signal and it needs to be able to handle that. Long story short, I have no clue if the Monitor Audio driver will work well with the port plugged. It might but someone will have to try it and report back - or contact Monitor and ask them.

Bringing this back to the beginning, I still think the sweet spot for the Aiyima A20 is to use the high pass filter matched to a small sealed speaker. Other uses cases will still have reduced distortion in the main speakers due to blocking low frequencies but the crossover will not be optimum. Given that the A20 subwoofer output is fixed at 200 Hz and only has max voltage out of ~900 mV, I prefer running a full range signal to an active sub and using its built in filter. For example, the SVS powered subs have very good built in filters and on board DSP to tune their response.

If you are going to use the A20 sub out, I would look for an active sub that has the ability to bypass its built in low pass filter.

Having said all this, do not lose sight of the fact that the Aiyima A20 when used as a basic amplifier with volume control bypassed and no high pass filter, is a very good sounding, higher performance amp. No shame in just using it that way.

 

[fwwwk]

Quite off topic, quite on topic.
I received my A20 and managed to crossover decently my bass-reflex bookshelf speakers with subwoofer. So I guess it is possible even without DSP (in my case PC but applying minimal-phase EQ peak filters notoriously rolled phase, so I resigned).

Specification:
semi-treated room
80dBC target
Dynaudio Focus 160 plugged
Aiyima A20 HPF 100Hz
Canton Sub 600 0dB gain, 100Hz LPF, 60 deg phase
UMIK-1 + REW noEQ
plot 1/6 smoothed

 

[SlowJim]

My general rule for casual music listening is 90hz for 5" speakers, 80hz for 6-8" and 100hz for 4" and smaller.

 

[fwwwk]

This is 7" woofer with approx. tuning 70hz while enclosure plugged (based on similarly built Dynaudio Special 40 measurments) so I decided to gave it more energy in higher ends because I can center my sub so localization is not a big deal

 

[magreen]

Overall, these measured results are a serious disappointment to me. The distortion using RCA has improved somewhat over A70. Otherwise distortion is worse than the A70, and load dependency / PFFB are far worse than the A70. And performance is far below the performance leaders in the inexpensive class D amplifier space. So many steps backwards just to add one nice feature (HPF). Far from what I would expect at this stage of market maturity, after what we've seen from 3e Audio and Topping inexpensive amplifiers. And I say this as the owner of two Aiyima A70s and a bunch of older Aiyima equipment,

 

[Abu Rashid]

Is it a true balance amp ? Or just XLR connectors?

 

[Mark185]

It is true balanced input. The TPA3255 chip has true balanced input circuitry. The RCA inputs have to be converted internally by the Aiyima design before sending to the TPA3255 chip.

 

[ICIETDIYEUR]

To see well-studied filters with the expected answer, look at the O-NOORUS D4 Pro and ask its designer if necessary.
The choice of transition frequencies at +/-3dB (which is more exact) when it comes to 'HPF' or 'LPF' is also important, they are not the result of chance...

 

[fwwwk]

Yes, I am aware of this but their drivers are designed to work in both sealed and ported enclosures. I do not own any of them but in the past, I purchased Dynaudio drivers and built my own speakers with them. The classic Dynaudio 160mm driver had a Q of 0.7 for many years that could work in ported or sealed. It actually worked very well in something called an aperiodic enclosure that had small port(s) with damping material in it. Most drivers for ported designs have Q below 0.5 and when you put them in a sealed enclosure, the -3 dB frequency is up in the 100 Hz range. Dynaudio with a foam plug is very likely an aperiodic design and not a true sealed enclosure and as noted above, their 160mm drivers worked well like that.

Some of these drivers when put in a sealed enclosure, have a Q in the 0.5 range which rolls off in a very mild slope. Q of 0.5 is good from a standpoint of minimal phase shift but the 6" driver will still get fed significant low frequency signal and it needs to be able to handle that. Long story short, I have no clue if the Monitor Audio driver will work well with the port plugged. It might but someone will have to try it and report back - or contact Monitor and ask them.

Bringing this back to the beginning, I still think the sweet spot for the Aiyima A20 is to use the high pass filter matched to a small sealed speaker. Other uses cases will still have reduced distortion in the main speakers due to blocking low frequencies but the crossover will not be optimum. Given that the A20 subwoofer output is fixed at 200 Hz and only has max voltage out of ~900 mV, I prefer running a full range signal to an active sub and using its built in filter. For example, the SVS powered subs have very good built in filters and on board DSP to tune their response.

If you are going to use the A20 sub out, I would look for an active sub that has the ability to bypass its built in low pass filter.

Having said all this, do not lose sight of the fact that the Aiyima A20 when used as a basic amplifier with volume control bypassed and no high pass filter, is a very good sounding, higher performance amp. No shame in just using it that way.

Have u measured sub out output impedance? Straight forward solution to low level signal would be to use Y-splitter and feed your sub hotter twicing the voltage and increasing signal by 6dB. Would be easier to handle for a sub preamp section.

 

[Mark185]

I did not measure output impedance. Only measured RMS voltage output. I have decided to use external DSP with adjustable outputs for all channels instead. Higher cost but much better control over crossover frequencies and signal levels plus it allows me to use parametric EQ. I am using Dayton Audio DSP408.

I am also experimenting with building my own DSP using inexpensive boards from Sure Electronics under the Wondom brand name. I do not expect great SNR from the Wondom devices but I am using them to experiment and then will look into better hardware.

Bottom line for me is the built in crossover filters in the A20 don't fit my use case so I will use it as a basic amplifier and bypass the input volume control.

 

[Mark185]

Overall, these measured results are a serious disappointment to me. The distortion using RCA has improved somewhat over A70. Otherwise distortion is worse than the A70, and load dependency / PFFB are far worse than the A70. And performance is far below the performance leaders in the inexpensive class D amplifier space. So many steps backwards just to add one nice feature (HPF). Far from what I would expect at this stage of market maturity, after what we've seen from 3e Audio and Topping inexpensive amplifiers. And I say this as the owner of two Aiyima A70s and a bunch of older Aiyima equipment,

With normal pricing, the A20 is not competing directly with 3e Audio A7. I own an A7. When A7 goes on sale for $239, then yes it is superior performance and value to A20 selling for $195. When Aiyima drops A20 down to $159 sale price, then it is decent value and not competing directly with 3e A7.

Load dependency frequency response deviation into 4 ohms at 20 KHz is + 0.6 dB compared to its response at 8 KHz so while it may look bad on a plot where the vertical scale is exaggerated, its PFFB implementation is actually pretty good. I measured this using a Quant Asylum QA403 and 4 ohm load bank with Vishay non-inductive 50 watt resistors that I wired in series - parallel to get 200 watt load bank at 4 ohms.

SNR and THD+N measurements without the HP filter are also good. THD takes a significant hit when the HP filter is turned on but I doubt most of the Aiyima target audience can hear that difference. Here is measurement without filter that I posted earlier. The noise spikes on the left had side are artifacts of my test environment. There is a fairly strong radiated 60 Hz electromagnetic field that I can't block. It is coming from outside my home and the QA403 inputs are so sensitive, they pick it up. My audio equipment does not amplify this power line noise but it is measurable.

The THD peaks that are significant are the harmonics of the 1 KHz test tone on the right side.

Here is same plot with high pass filter turned on. Third harmonic does increase significantly but for the target audience, I don't think this is significant. Speakers in the lower price range have substantially higher harmonic distortion than this amplifier with the HP filter on.

 

[magreen]

With normal pricing, the A20 is not competing directly with 3e Audio A7.

Most of my criticism was directed to the A20's inferior performance relative to the Aiyima A70, not the 3e A7.

 

[Mark185]

Most of my criticism was directed to the A20's inferior performance relative to the Aiyima A70, not the 3e A7.

Understood. I don't have much to say that has not already been said. Used appropriately, the A20 is a pretty good amplifier. It has some deficiencies that can be exposed if used for critical listening with certain speaker designs but for the vast majority, these deficiencies are not audible. When used for casual listening - particularly as a desktop amp - the A20 is very good when purchased on sale. With filter and volume control bypassed, it more than holds its own against more expensive competitors in critical listening environments.

 

[Schollaudio]

What is the high pass filter slope?

 

[Fxfighter]

What is the high pass filter slope?

24db/octave

 

[jodrim]

What is the high pass filter slope?

AIYIMA A20 Stereo 2.1 Amplifier Review

@AIYIMA can you confirm only 6dB per octave? Better than nothing but its not the fully functional sub integration @Fxfighter claims 24 dB https://www.audiosciencereview.com/forum/index.php?threads/aiyima%E2%80%99s-new-balanced-amplifier-a20.64858/post-2448685

www.audiosciencereview.com

Aiyima said the high-pass filter is 12 dB/octave and 24 dB/octave for the low-pass filter

 

[Schollaudio]

If a person wants an all analog system with stereo 4th order active crossover below 200hz this subwoofer crossover Bellari sub crossover on the preamp output along with the A20 HPF tuned to a closed satellite rolloff and another sub amp can get the job done. REW would be needed for tuning.

MiniDSP is certainly more flexible.

 

[jodrim]

Is anyone with this amplifier able to use the 12V trigger with a 3.5 mm TS cable? I ordered a 5m 3.5 mm TS cable to use from my Topping DX5 II but it doesn't seem to work with the 12V trigger. It works with a 1m 3.5 mm TRS cable that I found so am unsure if it's the connector or the length that might be the issue. Although the A20 comes with a short 3.5 TRS so maybe that's the only type they've tested it to work with.

Edit: After experimenting a bit it seems to be able to turn on/off the A20 if I don't put the cable in all the way but just when it meets a bit of resistance. Then when it's turned on if I plug the cable in all the way it turns off. Feels a bit unsafe to use it like this though.

 

[andrewwnbanks]

This is a review and detailed measurements of the AIYIMA A20 stereo class D amplifier with high-pass filter. It was sent to me by the company and is on black Friday sale for US $157 (normally $195).
View attachment 491991
The A20 is the most elegant design I have seen from the AIYIMA. Not only is it stylish, it also has quite a bit of weight to it (for its class). The amp has both RCA and XLR balanced inputs which you can easily select with the switch on the right. It took me a bit to figure out that to activate high-pass filter, you push the toggle switch up a notch past "ON." Nice way to save a switch and still get the job done, allowing the design to look balanced.

Back panel shows everything you wanted but perhaps, had not managed to get in this class of amplifier:

View attachment 491992
OK, maybe not the giant, 10 amp 48 volt power supply. There is trigger input and of course, its high pass filter which you set with that knob. I like that it has detents and is rather stiff so you don't turn it by accident. You can bypass the volume control by pressing that button for a few seconds. In testing, I did not find a performance difference between using that, or setting the volume to max.

AIYIMA A20 Amplifier Measurements
I started with volume set by pass and high pass filter disabled using XLR input:
View attachment 491993
Distortion is kept quite low so noise sets the SINAD (more or less). At nearly 94 dB, this is excellent performance:
View attachment 491994
View attachment 491995
It is awfully close to our blue range despite the diminutive size and cost. You lose a bit of performance as usual if you use RCA:
View attachment 491996

Here is actual noise performance which again for the class is excellent:
View attachment 491998

Despite implementation of PFFB, there is a slight load dependency:
View attachment 491999
And that general peaking. High pass works as advertised.

Multitone and 19+20 kHz tests show the typical behavior of rising distortion in upper ranges:
View attachment 492000
View attachment 492001

Channel separation is better than average (for all amps):
View attachment 492002

The beefy power supply turbo charges the amplifier, producing a lot of power in such a small package with 4 ohm impedance:
View attachment 492003
View attachment 492004

It is able to maintain that close to bottom of hearing range at 40 Hz:
View attachment 492005

8 Ohm output is of course diminished but still respectable:
View attachment 492006

As noted, high frequencies are the enemies of this platform:
View attachment 492007

Amplifier was stable on power on:
View attachment 492008

It does however potentially have a power on/off pop:
View attachment 492009

Conclusions
It is amazing how far we have come in this category of amplifier. AIYIMA was one of the earliest adopters producing performance that was hard to imagine at the time. In A20, it has managed to bring more and more refinement as to define a new class here. Yes, there are a few minor misses like flatness of frequency response but generally, you have a very power full amplifier, with low noise and mostly, low distortion. Combine it with good looks and nice functionality such a proper high pass filtering for subwoofer use and you have a winner here.

I am going to recommend the AIYIMA A20 stereo amplifier.
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As always, questions, comments, recommendations, etc. are welcome.

Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

All very interesting, but what does it SOUND like?

 

[hipoagu]

All very interesting, but what does it SOUND like?

All that review means the amplifier does amplify source signal and does not add audible noise or distorsion for all the normal range of volumes and loads (speakers) you may think of connecting. It outputs an amplified version of the input signal which is what is meant to do. If you want to "sound like" something you may add eq after the source (wiim streamers have very powerful eq and parametric eq plus room correction features).