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AIYIMA D03 class D amplifier "Subjective review"

rmerchant3

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Cool beans bro! I like the D03 and did wonder about the sub. Even Aiyima state the D03 has the edge over the D05 in regards to control over the sub so it is nice to read this as confirmation. I agree about the treble too. I have to increase the treble to very nearly max output to get a relative balance using Bluetooth which is not a deal breaker by any means as it does sound very good once implemented. Overall I would agree a great little desktop amp that certainly covers the digital l/O bases I would need with out adding a Dac and for less than £100!
Have you had a chance to compare it to any other similar integrated amps in this price range and category?
 

dbbright

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The difference in heat generation between D03 and A30 is caused by the difference in the amplifier chip used.
The Infineon MA12070 used in the A30 is an amplifier chip that maximizes power efficiency. All amplifiers that use this generate very little heat. However, it is an amplifier chip that is not suitable for obtaining a large output.
On the other hand, the TI TAS5624a used by the D-03 is a digital input amplifier chip that pursues sound quality and high output like the TPA325x series.
I think that the difference in the characteristics of these two amplifier chips is also reflected in the sound quality of the D03 and A30.

Very interesting. Do you have an opinion on the sound quality between the two?
 

Toku

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Very interesting. Do you have an opinion on the sound quality between the two?
How you feel the sound quality varies from person to person. So it's not as clear as the electrical measurements of ASR. My subjective impression is that if you want a powerful sound, it's D03, and if you want a delicate sound, it's A30. I bought D03 but not A30. However, I bought 3 SA300s of the same type. I have also purchased several types of amplifiers that use the MA12070 chip.
 

dbbright

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Has anyone tried the subwoofer output? Is it sufficient? Any problem to cross the speakers at desired frequency from the sub?

This is a review from amazon:
Sound is okay but when playing through bluetooth there is a sounds poping into my subs but only by using bluetooth connection
Almost a month now and still has popping noise when bluetooth is in use while playing music and when you pause i hear popping noise
Interesting about the sub woofer and Bluetooth connection accompanied by a 'popping'. Could it be the Sub itself rather than the amp, just a speculative question. I have a pair of Mission 751s with a 5 inch bass cone and I am considering pairing up a Sub with them. I would appreciate anybody with a similar setup using the D03 to leave any feedback. I am wondering if the sub will eat up the bass from the two Missions as opposed to an actual separate offering altogether. I am considering the Presonus Eris Sub 8 for the task in hand but if anybody has any suggestions for a sub within that price range I would also appreciate your feedback. There are a another two choices i could make one being the Wharfdale SW150 and the Cambridge Audio SW120, again all around the £150 area here in the UK.
I know the D05 has a separate feed for the sub using dual op amps and at this point i am unclear as to which unit may have the superior sub sound but I may speculate here and say it could the D05. Aiyima does not make it clear and seems to suggest that the D03 via DSP has the better offering but i may have misunderstood the accuracy of that statement which may have been lost in translation.
The D05 uses an Op Amp to provide the Filter for the Sub as the chipset used doesn't support a third channel natively. The D03 does all the processing within the DSP - including the Bass and Treble controls. There is actually no reason why the D05 should sound "Better" than the D03. In fact the D03 with its DSP based filters could potentially provide much better handling of the Sub and the cross over between the sub and the main speakers. You need to set up the D03 using the menu system if you are going to use the Sub output.

I believe the newer and current chipset used in the D03 can provide up to 8 channels with the D03 implementation only using three - Left and Right main speakers and one channel used for the Sub. All the clever stuff is done in software by the DSP. The D05 uses a much older chipset that is now considered obsolete by Texas Instruments (chipset supplier) and no new amplifiers are being designed on this obsolete chipset.
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I have never used a sub before but in respect of finding the cut off frequency that would be possible by the adjustments on the sub and using your ears..
I don't think this is the case with the D03 as the cut off frequency is defined in software and the sub will only provide the set of frequencies provided from the Sub out RCA connection. My understanding is this output is not the full frequency spectrum just the lower frequencies specifically for the Sub. So setting the controls on the Sub will need to take this into account.
Sub output usually have a High pass filter (very rare) for cut off the low frequencies from the main speakers or a low pass filter that will cut off the high frequencies from the subwoofer.
With out high pass filter the speakers will play at full range.
In some cases is just a line out.
My opinion is that low pass filters are useless because modern subs will do that anyway. High pass filters is very difficult at this price point amplifiers..

Man… I’m still confused by how to properly set up my sub (SVS PB-1000), or if it’s even possible using the D03. Can I just set the low pass filter on the sub based on the frequency range of my main speakers and adjust as needed? Any reason that wouldn’t work, or do I need to look a different amp like the Loxjie? Any help would be much appreciated as a lot of the discussion is still over my head at this point!
 

rmerchant3

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Man… I’m still confused by how to properly set up my sub (SVS PB-1000), or if it’s even possible using the D03. Can I just set the low pass filter on the sub based on the frequency range of my main speakers and adjust as needed? Any reason that wouldn’t work, or do I need to look a different amp like the Loxjie? Any help would be much appreciated as a lot of the discussion is still over my head at this point!
Your thinking is correct. A good place the start is at the rated lowest frequency range of the speakers you're mating the subwoofer up to. For example: if the main speakers lowest rated frequency range is 60Hz, you would set the low pass filter on the subwoofer at 60Hz and adjust to your liking from there.

You will likely find that you'll end up setting the subwoofer crossover 10Hz to 20Hz above the lowest frequency of your main speakers though. This is because a lot of speakers manufacturers are generous in the low frequency output ratings. The mains may be able to produce the lowest "rated" frequencies, but they will be at significantly lower dB than what your ears will likely prefer. Human hearing is not as sensitive to lower frequency sounds as it is to higher frequencies. This is why a a slight dB bump in the lower frequencies is generally preferred. All of this obviously comes down to the individuals liking.

Also, the crossover on most subwoofers is not a brick wall setting. For example: if you set it at 60Hz it will still play frequencies in the 70Hz, 80Hz, and maybe even 100Hz range but will roll off those frequencies in a progressively negative dB range according to the crossover in the sub. This is done so that the bass integrates smoothly with your mains.
 
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gmz_001

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I'v noticed low quality of analog input. D03 use PCM1808 for ADC. Cheap adc, but it sounds preety good at Edifier Rxxxx multimedia speakers.
I'v measured ADC input filter components value. There is low pass filter with -3db frequency at 2.6kHz. That's the problem. Dont know, it is mistake from assembly line, or it's schematic mistake.
C145 capacitor should be ~2.4nF for LPF frequency at 24 kHz cause ADC work at 96kHz with limit of input audio frequency 48kHz.
Schematic for one channel, another channel similar, but several component have no marking on pcb. I'v removed C145 and similar capacitor from another channel. Analog input sounds good.
That is orignal ADC input LPF schematic. Have no pcb photo for showing that capacitors. I'll add photo later.
 
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rmerchant3

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I'v noticed low quality of analog input. D03 use PCM1808 for ADC. Cheap adc, but it sounds preety good at Edifier Rxxxx multimedia speakers.
I'v measured ADC input filter components value. There is low pass filter with -3db frequency at 2.6kHz. That's the problem. Dont know, it is mistake from assembly line, or it's schematic mistake.
C145 capacitor should be ~2.4nF for LPF frequency at 24 kHz cause ADC work at 96kHz with limit of input audio frequency 48kHz.
Schematic for one channel, another channel similar, but several component have no marking on pcb. I'v removed C145 and similar capacitor from another channel. Analog input sounds good.
That is orignal ADC input LPF schematic. Have no pcb photo for showing that capacitors. I'll add photo later.
Very good information. Please do add the PCB picture later as that would be greatly helpful. I personally do not use mine for the analog inputs, but I have heard it sounds like the volume is low on it when in use. Looks like you found the culprit.
 

Toku

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It is a photograph of the analog input part.
 

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gmz_001

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, but I have heard it sounds like the volume is low on it when in use. Looks like you found the culprit.
Volume difference caused by voltage divider by two R116/R117 (marking for one channel). Level up could be made by decreasing R116 value.
At my case there is sound withoud mid/high range. At that case capacitor value could be measured without desoldering - ic make no notable error for measure process.
At photo caps changed for 2.2nF caps. also replaced signal paththrough ceramic cap c136 by film caps.

 

joeren

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Volume difference caused by voltage divider by two R116/R117 (marking for one channel). Level up could be made by decreasing R116 value.
At my case there is sound withoud mid/high range. At that case capacitor value could be measured without desoldering - ic make no notable error for measure process.
At photo caps changed for 2.2nF caps. also replaced signal paththrough ceramic cap c136 by film caps.

A few things worth noting. You replaced the ceramic caps with film, probably because of film capacitors being linear. You added a huge inductance, made up by the long film capacitor’s long leads and large open loop. The capacitors circled in your photo are NP0 type (easy to tell the difference by the gray color compared to the brown X7R type. NP0 capacitors are as linear as film capacitors and won’t add that huge inductance.
 

gmz_001

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I'v mounted 2.2nF np0 cap for LPF. Original cap is x7r. But there is no np0/c0g with huge value like 1uF for decoupling cap, maximum - 0.033uF. Have no chance to measure inductance of leads, not sure it is huge enough in compare with pcb trace inductance.
 
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joeren

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I'v mounted 2.2nF np0 cap for LPF. Original cap is x7r. But there is no np0/c0g with huge value like 1uF for decoupling cap, maximum - 0.033uF. Have no chance to measure inductance of leads, not sure it is huge enough in compare with pcb trace inductance.
Yes, understood but the PCB trace loop inductance is very tight. In the end, for audio frequencies, there is most likely no performance degradation.
 

gmz_001

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I'v made a test - Input filter reaction for square wave impulse. One with smd cap, another one with film cap. Can't see any inductance ringing in range of 100kHz. No doubt that there is difference at high frequency, but not in audio range.
 

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joeren

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I'v made a test - Input filter reaction for square wave impulse. One with smd cap, another one with film cap. Can't see any inductance ringing in range of 100kHz. No doubt that there is difference at high frequency, but not in audio range.
If, for example, you characterized them on an impedance/gain phase analyzer, (Agilent 4294A). You would begin to see a difference at several MHz. I’ve done this 1000s of times, in search of optimizing high frequency circuit components, to be use in x-ray gridding applications. For audio frequencies, not so much.
 

sojun80

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I see. So why is my amp case cooler now? We have now come into winter so the room temp has dropped over the last few days so that's one mitigating factor to consider. Oh well, it looks like i have a little mystery as to why my amp is running cooler...:cool:
index.php
Even a small dip in ambient temps can make a huge change in that.

Also it could be you are just wrong in your analysis of how fast it heats up.

Also you could have messed up re-pasting and the chip itself just is much hotter but not transferring the heat as quickly.

I've been a GPU miner for years, repasting does not make a heatsink cooler, it should make it warmer sooner, because it's getting the heat more efficently. We do not have the tools to tell if repasting does anything useful or harmful, unlike a graphics card where we can view the thermal temps of the chips.
 

bathroomskank

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Is it a bad idea to lower the bass from the amp and add some gain to the subwoofer to achieve the equivalent of a high pass filter for the speakers ?
 

Timstunes

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I've always been a class A/B type of guy, but years ago, I found a number of rooms/setups where the SMSL SA-50 amp was perfect for the need. I own two, and still use them. For a while, I dabbled in TPA3116 self-builds with Pyramid power supplies. The aesthetics were lacking, but the sound was good. And recently, I purchased the Aiyima a04 amp and wound up also getting an a07 for nearly free. I think the latest class D generation in the $50-150 price range is delivering very good sound for the investment. The a07 amp is plenty powerful, of decent construction, and I am very pleased with the sound. I just unplug the power supply when it's not in use as an extra caution/saves energy.

Thanks for the nice review, Roberto. I appreciate your post and comments. I hope that Class D amps will continue to march on, as I think they really are in the center of the game now. Techs who work on older equipment are getting scarcer and restoring an older amp or receiver can be quite expensive and frustrating. For a lot of folks, these under $150 class D amps are a perfectly fine way to go. Are any of us going to keep these as long as we've kept the classic receivers from the 70s? No, but they are dependable, sound good and take up a small amount of space with minimal heat.
Thanks for posting. My experience has been the same as yours. IMO these products offer very good sq for many who otherwise may not be able to have it. I personally also find them fun and convenient and a few are amazing.
 

dgallo

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We use Mean Well LRS-200-24 Power Supplies with these units with KEF Q-series or Denon (made by Mission) bookshelf speakers.

First, thank you all for the information provided. I´ve been reading almost all messages. About power supply for the do3, Why are you using this 24v PS? Wouldn't be better to have a 36v one? I´m about to buy the amp and was think to get it without the 32v provided PS and get the aiyima 36v 6a instead. Do you recommend that or will be better to get the same you use? Thanks!
 
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