Aiyima’s new balanced amplifier- A20

[Mark185]

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?

The high pass appears to have a non-linear response that starts out at 6 dB/octave for the first octave below the crossover set point. It then has a 12 dB/octave slope in the second octave below the set point. It has been many years since I studied analog filter design in engineering school. I need to go back and do some research to see if this is normal for a filter to start at one slope and transition to a steeper final slope 2 octaves away from the setpoint.

If that is the case, I have been wrong all along and Aiyima is right. There is a filter parameter known as "Q" that affects the shape of the curve in the crossover region. Perhaps that is what we are observing. A Q value of 0.5 would have a more gradual initial rolloff that gets steeper. A Q of 0.7 yields what is considered optimal Butterworth response. Does not mean Q=0.5 is a bad thing. Q=0.5 is associated with optimum phase shift thru the crossover region if I remember correctly.

 

[Tontom]

Okay, then I guess I was wrong with my assumption and my measurement isn't relevant in this case.

If that's the case, sorry AIYIMA

 

[Mark185]

@AIYIMA I owe you an apology about claiming the high pass filter is 6 dB/octave. I am an electrical engineer and I should have known better than to publish a negative finding without thoroughly reviewing my test procedure, test data, and theory of filter design. It has been 40 years since I studied filter design and I forgot that the rolloff rate is not 12 dB/octave initially but that it converges to a final rate of 12 dB/octave about 2 octaves below the cutoff frequency. I also forgot about the effect of the 'Q' factor.

My mistake was that I measured rolloff rate close to the cutoff frequency I set on my amplifier. Setting was 80 Hz and I measured from 80 down to 40 Hz. If you look at the plot below, you can see that the initial response varies considerably depending on 'Q' factor.

 

[sergiomiranda]

@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.

@Mark185 I thank you for your effort in analyzing the specifications and performance of the device and asking for clarifications, we are now better informed thanks to that. I just think we can all try to be a bit more patient, that's all.
However, I disagree in that last part, I do think it is useless to speculate on how companies internally handle issues with their products, what is relevant to us users/consumers is how they handle it externally by the answers given and actions taken.

 

[toilagamer852]

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.

I'm leaning more toward a separate amp than the wiim tbh. I'm currently using the Topping D50iii which I believe is a very good DAC and I just need a decent amp with HPF to pair well with both the Topping and the SVS

 

[ziggurcat]

I'm leaning more toward a separate amp than the wiim tbh. I'm currently using the Topping D50iii which I believe is a very good DAC and I just need a decent amp with HPF to pair well with both the Topping and the SVS

I would honestly give the new Topping Mini300. If the review comes out, then there can be a fair comparison, but the Mini300 -- from what's on paper, at least in terms of the spec sheets -- looks to potentially perform pretty similar to the PA5 II. That is not to say that this amp wouldn't also be appropriate, and there's real, objective data to add to the decision-making process (the Mini300 performance is pure speculation at this point, IMO).

 

[Mark185]

I'm leaning more toward a separate amp than the wiim tbh. I'm currently using the Topping D50iii which I believe is a very good DAC and I just need a decent amp with HPF to pair well with both the Topping and the SVS

Then the Aiyima A20 should work well for you.

 

[toilagamer852]

I would honestly give the new Topping Mini300. If the review comes out, then there can be a fair comparison, but the Mini300 -- from what's on paper, at least in terms of the spec sheets -- looks to potentially perform pretty similar to the PA5 II. That is not to say that this amp wouldn't also be appropriate, and there's real, objective data to add to the decision-making process (the Mini300 performance is pure speculation at this point, IMO).

It has no HPF though

 

[AIYIMA]

Okay, then I guess I was wrong with my assumption and my measurement isn't relevant in this case.

Okay, then I guess I was wrong with my assumption and my measurement isn't relevant in this case.

If that's the case, sorry AIYIMA

No worries at all, and thank you for your interest and detailed analysis of our product!
We truly appreciate your expertise and look forward to any further professional feedback you may share.

 

[AIYIMA]

@AIYIMA I owe you an apology about claiming the high pass filter is 6 dB/octave. I am an electrical engineer and I should have known better than to publish a negative finding without thoroughly reviewing my test procedure, test data, and theory of filter design. It has been 40 years since I studied filter design and I forgot that the rolloff rate is not 12 dB/octave initially but that it converges to a final rate of 12 dB/octave about 2 octaves below the cutoff frequency. I also forgot about the effect of the 'Q' factor.

My mistake was that I measured rolloff rate close to the cutoff frequency I set on my amplifier. Setting was 80 Hz and I measured from 80 down to 40 Hz. If you look at the plot below, you can see that the initial response varies considerably depending on 'Q' factor.

View attachment 495384

No worries at all, and thank you so much for your thorough and professional clarification!
We truly appreciate your detailed analysis as an electrical engineer regarding the testing methods and data.
Technical matters can be complex, and details of filter design are easy to overlook.
Thank you for patiently sharing your explanation about the initial rolloff rate and the effect of the 'Q' factor — it’s extremely valuable for both our team and other users.

Once again, we sincerely appreciate your expertise and support, and we look forward to more of your valuable feedback in the future!

 

[Gibsonian]

Then the Aiyima A20 should work well for you.

I’ve one and it sounds excellent to me

 

[Tontom]

I even bought the T20 as well, and after a day of listening, I switched back to just the A20 to see if there was a difference. Wow, it sounded different! The T20 added more fullness to the overall sound. I haven't regretted the purchase at all.

Thumbs up for AIYIMA!