Aiyima’s new balanced amplifier- A20

[caught gesture]

I suspect this is a problem for Aiyima. The A20 is a flagship product for them. Any criticism is bound to cause problems for someone in their company. I do think it is worth repeating. The basic amplifier is very good.

I agree that as an amplifier it does well. The problem, for me at least, is that I purchased it for the HPF, sub out and increased power output. I’ve got a great amplifier that I wanted to replace for these benefits. The power specs are not real world use and neither are the HPF specs according to what Aiyima is stating and what users are measuring.

 

[Mark185]

I agree with you on the poor filter implementation. I have not even posted about the subwoofer out but it is not good unless my A20 is defective and a good production example will perform differently. I have measured the sub out as having a constant output no matter what the input signal level or volume control is set at. It is fixed at 200 Hz 24 dB/octave but the output signal is not useful if it stays at one fixed level. I have written an email to @AIYIMA asking if the sub out on my unit is defective.

For now, I am using mine without the HP filter or the subwoofer output. I have a Dayton Audio DSP408 doing the filter functions and it does sound quite good. I know the cost of the DSP408 is more than the A20 so this solution is not for everyone.

 

[fwwwk]

constant output of sub out regardless of absolute volume would make this device not useless for sub, it would make it simply defective. hard to believe such mistake honestly. @AIYIMA please refer if possible to this and to the hpf filter order.

 

[caught gesture]

@AIYIMA Ignoring a problem does not make it go away. The longer your customers have to wait for some clarification, the more your reputation suffers. I’m getting close to boxing up the amplifier and sending it back for a refund. I don’t want to as I bought a 48V/10A GAN power supply from another retailer to upgrade the power supply you provided, an RCA to RCA sub cable, as well as a new DAC with volume control, all to use your amplifier based on the specifications on your website. Sending your amplifier back basically makes all those other purchases unnecessary.

 

[Tontom]

Unfortunately, I see it the same way; to initially appear customer-oriented and then to run for cover at the first sign of difficulty is not good manners.

 

[Mark185]

I am speculating here but the appearance is that this was released to meet a deadline for their anniversary without completing the design or acknowledging it was flawed. This was compounded by Amir doing an abbreviated test because he has a huge backlog. Had he tested the subwoofer output, I am fairly certain he would have found what I found. It is fixed in both rolloff frequency and output level - unless my sample is defective. It also has much higher distortion than the amplifier full range outputs have.

Note: If my A20 is defective and the active circuitry driving the subwoofer output is not working, that would explain the very low output level and high distortion. I have attached freq response plot which clearly shows the output level does not change with varying input signal amplitude. I have also attached a distortion plot which indicates approximately -42 dB gain and very high distortion products. The test frequency is 44 Hz. There are prominent spikes at the power line frequency and its harmonics and that is not the amplifier's fault. That is a problem with my test setup. If the subwoofer output was tracking the high pass ouput, then the power line harmonics would not be as detrimental. I will repeat, if my A20 is defective then these plots may not be representative of what a good working A20 can do. Unfortunately, I am past the return window for my A20 and Aiyima has not responded to my personal email to their support line for help.

 

[caught gesture]

Unfortunately, I am past the return window for my A20 and Aiyima has not responded to my personal email to their support line for help.

I don’t know where you are located but here in Europe that return window of Aiyima is superseded by EU consumer protections.

1. Legal Guarantee: In the EU, all new products are covered by a legal guarantee of two years. This means that if the product is faulty or not as described, you can request a repair, replacement, or refund, regardless of the manufacturer's policy.
2. Defective Products: If the electronic equipment is found to be defective during the warranty period, you have the right to have it repaired or replaced free of charge. If this is not possible, you may be entitled to a price reduction or a full refund.
3. Return Period: The 14-day return policy stated by the manufacturer usually pertains to the right of withdrawal, allowing you to change your mind about a purchase. However, this is separate from the legal guarantee.

 

[Mark185]

There are no protections like that I am aware of here. I know from past experience that if I call Amazon customer support and explain the situation clearly, there is a decent chance they will refund my money. This happened with an oscilloscope I purchased earlier this year that was defective. The catch there was I first sent the scope to the manufacturer for warranty service and they returned it still not working correctly. After that, Amazon took care of me.

 

[AIYIMA]

Dear ASR audio enthusiasts,

Thank you for your attention to and valuable feedback on the A20. We have noted the issues you mentioned and will conduct a thorough inspection. At the same time, we will record a test video and share it with you promptly. Please kindly wait for the results of our inspection, and thank you for your support!

 

[Tontom]

Better late than never.
Thank you for your reply.

 

[sergiomiranda]

I saw the first posts questioning the HPF specs in the other thread on November 25 and 26. That was just a week ago, so I think we could be a bit more patient, avoid accusing them from "running away" from providing answers after a few days, jumping to conclusions and start speculating how this will be an issue for someone internally. Do we need this drama?

 

[Mark185]

I saw the first posts questioning the HPF specs in the other thread on November 25 and 26. That was just a week ago, so I think we could be a bit more patient, avoid accusing them from "running away" from providing answers after a few days, jumping to conclusions and start speculating how this will be an issue for someone internally. Do we need this drama?

I have taken a balanced approach with my comments acknowledging what is good about the A20 and presenting test data I generated. No we don't need drama but we should be able to get a valid response from @AIYIMA the presents a solution.

I will add a bit more. The Douk amplifier with a high pass filter is also 6 dB/octave but that amp costs half of what the A20 sells for. At the $200 price point, I do not think it unreasonable to expect a 12 dB/octave high pass filter. I also think it is reasonable to expect a subwoofer output that is actually useful and not attenuating the signal by 42 dB as my A20 amplifier is doing. The sub out should also track the Left and Right channel out high pass signal level. Fixed sub out means the user has to adjust the subwoofer amplifier separately every time the main volume is changed. If what I measured is how all of these A20 amplifiers function, then the $200 price point is not a good deal.

@sergiomiranda I am an electrical engineer with more than 30 years experience and know a thing or two about what happens in a company when a product is shipped with a flaw and customers complain. It is not useless to speculate this has caused problems inside Aiyima and that probably has something to do with the response time to our queries.

 

[caught gesture]

I will add that 6dB/octave is not considered a useful HPF for mains/sub integration. 12dB/octave to 24dB/octave is the range for real world applications.

 

[Tontom]

@Mark 185 :
The subwoofer control on your unit appears to be faulty. The subwoofer volume control works perfectly on the A20 (just as it does on my Denon and Yamaha amplifiers).

 

[Mark185]

@Mark 185 :
The subwoofer control seems to be faulty on yours. The subwoofer volume control works the same on my Denon and Yamaha amplifiers.

It would not surprise me to find out my example is faulty and I think it will be a good result if the sub out design turns out to be working well for other people. I don't think the fixed 24 dB/octave 200 Hz filter response for the sub is a bad thing. I only questioned the fixed volume at -42 dB.

 

[AIYIMA]

Dear ASR audio enthusiasts,

Regarding the A20’s HPF (High-Pass Filter) Slope Design
The A20’s HPF slope is designed at 12 dB/oct. As shown in the test chart, within the 50–100 Hz frequency range, the signal attenuation changes from approximately –22 dB to –10 dB, resulting in a difference of about 12 dB. These figures are taken from our laboratory’s on-site test videos and measurement results, accurately reflecting the A20’s actual filter performance.

Regarding the SUB OUT (Subwoofer Output) Level
Based on extensive user feedback and application-scenario research, the A20’s SUB OUT port adopts a 2V output level, maintaining a 1:1 relationship with the A20’s RCA input level. Additionally, the subwoofer’s volume can be controlled directly via the A20’s main volume knob, ensuring convenient system-level adjustment.

Regarding the Subwoofer Output Crossover Characteristics
The frequency of the subwoofer output signal does not automatically change according to the HPF adjustment. Implementing an auto-crossover mechanism within a fully balanced circuit would significantly increase circuit complexity, potentially affecting overall performance. It would also require multi-gang potentiometers, which, due to inherent manufacturing tolerances, can introduce substantial resistance discrepancies that negatively impact circuit balance. For these reasons, the current design adopts a fixed crossover approach to ensure optimal stability and consistent sonic performance.

A20 Testing Details：https://drive.google.com/file/d/179OaJmBeVoSRDWOqb-WywThoT5mHs9RH/view?usp=sharing

 

[fwwwk]

Thank you for detailed answer Mr Aiyima.

If sub out has fixed crossover and hpf for main terminals is variable, therefore sub out has to have its own hpf and lpf (i assume both 24db/oct) right?

 

[toilagamer852]

So, Aiyima A20 or Douk A5 with regard to combined quality of the amp itself + the HPF? I just pulled the trigger and bought my sub (the SVS SB-1000 Pro) a few days ago.
Or something else entirely like miniDSP or Wiim amp?

 

[Tontom]

The high-pass filter (HPF) was set at 200 Hz, and it has a 6 dB reduction at the next octave (100 Hz).

Or am I seeing this wrong?

 

[Mark185]

So, Aiyima A20 or Douk A5 with regard to combined quality of the amp itself + the HPF? I just pulled the trigger and bought my sub (the SVS SB-1000 Pro) a few days ago.
Or something else entirely like miniDSP or Wiim amp?

The Wiim Amp Pro with built in DSP is far superior to the Aiyima A20. it costs a significant amount more but it is worth it. I have the Wiim ultra preamp which has same DSP filter and EQ functions as the Wiim Amp Pro. I use the Wiim with an SVS active subwoofer and an Apt Holman stereo power amplifier in my TV room.