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AIYIMA D03 class D amplifier "Subjective review"

Zek

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Sorry ADC?
The analogue is not converted to digital in the amplifier. The amplifer is an analogue device. There is a DAC for converting digital to analogue - not the other way around.
No, you're wrong - this is a fully digital amplifier where the digital signal goes directly to the output chip, and there is a special ADC chip for the analog signal.
 

tonycollinet

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No, you're wrong - this is a fully digital amplifier where the digital signal goes directly to the output chip, and there is a special ADC chip for the analog signal.
So there is. Apologies to @Bushellj

The amp chip takes in PWM, so I'd assumed they would just have a simple analogue to PWM stage. But no, they've implemented full ADC for it just to be immediatley converted back to analogue again via digital to PWM then into the PWM input amp.

Seems an odd way to do it but presumably they had reasons. Perhaps an ADC chip is cheaper than analogue to PWM conversion.
 

bloomdido

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The amp chip takes in PWM, so I'd assumed they would just have a simple analogue to PWM stage. But no, they've implemented full ADC for it just to be immediatley converted back to analogue again via digital to PWM then into the PWM input amp.
Where did you get this information? Usually PWM amps are analogue-first with separate DAC just like A/B.

Edit: I see it uses PCM1808 ADC... Probably you're right
 
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Bushellj

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Sorry ADC?

The analogue is not converted to digital in the amplifier. The amplifer is an analogue device. There is a DAC for converting digital to analogue - not the other way around.
Hi Tony.

The Aiyima D03 is a digital amplifier. The chipset has digital inputs if you check out the TI Datasheet.

If you want analogue inputs for this chipset then you need an ADC in front of the amplifier chipset. This is exactly what you have in the D03 and potentially why the Digital inputs sound better as there is no additional conversion going on.

This is why the design of the D03 is fundamentally different to most of the other so called Digital Amplifiers on the market.

Just to confuse matters of course all digital amplifiers are basically analogue devices but it depends how you process the incoming signals whether this is done in the digital domain or whether converted to Analogue first.

Update : I see now that several other people already replied !! There are several ways to “skin a cat“ as they say. I actually rather like the chipset used in the D03. It takes a lot more understanding to implement this chipset and requires software programming. The TPA325x chipset is much simpler to implement as it’s basically an analogue amplifier so no digital or software stuff to worry about. I have many TPA325x amplifiers but the little D03 is a refreshing break from the norm.
 
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bloomdido

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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..
If this amp has high pass filtering for main speakers it is done in digital domain so it's not difficult at all.
 

tonycollinet

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Hi Tony.

The Aiyima D03 is a digital amplifier. The chipset has digital inputs if you check out the TI Datasheet.

If you want analogue inputs for this chipset then you need an ADC in front of the amplifier chipset. This is exactly what you have in the D03 and potentially why the Digital inputs sound better as there is no additional conversion going on.

This is why the design of the D03 is fundamentally different to most of the other so called Digital Amplifiers on the market.

Just to confuse matters of course all digital amplifiers are basically analogue devices but it depends how you process the incoming signals whether this is done in the digital domain or whether converted to Analogue first.

Update : I see now that several other people already replied !! There are several ways to “skin a cat“ as they say. I actually rather like the chipset used in the D03. It takes a lot more understanding to implement this chipset and requires software programming. The TPA325x chipset is much simpler to implement as it’s basically an analogue amplifier so no digital or software stuff to worry about. I have many TPA325x amplifiers but the little D03 is a refreshing break from the norm.
See my post two above yours. The amplifier chip in the chipset takes PWM input which strictly speaking is not a digital signal (the pulses don't represent numbers)
 
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tonycollinet

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tonycollinet

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So there is. Apologies to @Bushellj

The amp chip takes in PWM, so I'd assumed they would just have a simple analogue to PWM stage. But no, they've implemented full ADC for it just to be immediatley converted back to analogue again via digital to PWM then into the PWM input amp.

Seems an odd way to do it but presumably they had reasons. Perhaps an ADC chip is cheaper than analogue to PWM conversion.
Answered my own question - the audio processor chip in this amp accepts up to five digital channels for conversion to PWM. It also does a lot of audio processing, including volume control. By ADCing the analogue input, it becomes just another digital stream that can be treated like all the others in the processor.
 

Bushellj

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Answered my own question - the audio processor chip in this amp accepts up to five digital channels for conversion to PWM. It also does a lot of audio processing, including volume control. By ADCing the analogue input, it becomes just another digital stream that can be treated like all the others in the processor.

The audio processor part of the chipset is the clever bit. I think this one actually has 8 channels of PWM output as it designed to be used in home cinema type setups with multi channels of audio. All “Digital” amplifiers convert to PWM for the output stage and then it’s just some nice fast FETs to switch the current needed at the speakers !!!

As we don’t have any circuit diagrams from Aiyima on any of their products the architecture just has to be guessed but I am sure it will follow the manufacturer‘s data sheet guidelines pretty closely. I am not sure how the analogue sub output is generated but I assume it will be using one of the spare PWM outputs from the Audio Processor chip and all the filtering will be done on the DSP in software.

The Aiyima D03 uses some particular interesting chip choices, usually high quality. Only the ADC seems to be rather basic but then this amplifier is built to a cost. I don’t think it is an Aiyima original design unless they just subbed the work out to a third party. Never sure with these Chinese “Manufacturers” whether they are just Sales and Marketing companies or whether they actually design all the products in house and Manufacture. Manufacturing of course is also subbed out in most cases.
 

tonycollinet

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A valid point for the analogue input - given that there are 4 separate digital inputs it is most likely that the analogue input is likely to be used for old tech soruces - vinyl or tape. In which case even a relatively poor ADC is likely to be good enough.

One problem with the architecture though is there is no possiblity for post filter feedback.
 

svinyard

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OK so I got the D03 and tested it out with a few different speakers etc.

Everything sounded good/great out of this thing to my untrained ears. The Fluance RT82/ART DJ Pre II turntable into its RCA sounded pretty darn good to us (some have said it lacking). I wasn't able to AB it with a different amp but it sounded good enough for our untrained ears. Bluetooth sounded great as well. Of note, the build quality is a bit lame. Volume knob wobbles a bit when using it. The Bluetooth drops you when you aren't using it so you have to go and reconnect on the iPhone. This is actually pretty damn lame. I don't want to constantly have to make those clicks as its not just a short quick thing on my iPhone. BT range was good tho and it got plenty loud for us. Especially on the Klipsch R-51M's. I did like being able to adjust the input without the remote using the switches (wobbly) on the front. It was easy. Display light is kind of lame but the display is small so not bad.
 

Giampa70

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For more info about output power you can read TAS5624 datasheet.
On figure 1 you can see about 2x70W 8Ohm and 2x115W 4Ohm with 36V supply voltage and 0.1% THD+N.
Reading figure 2 and 4 could be estimated about 2x55W 8Ohm and 2x90W 4Ohm with 32V supply voltage and 0.1% THD+N.
You also have to know 8Ohm power is limited by supply voltage but 4Ohm power is limited by supply ampere, it should be not less than 6A for full power.
With 5A should be a little bit less than maximum possible at 4Ohm.
That's all about power
 

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galapogos

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Hi, I may have missed it, but any idea what the low pass filter is set to on the sub out?
 

rmerchant3

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I have been comparing the Aiyima D03 with the Loxjie A30 over the past week and ran across this thread in an attempt to help me make a decision. It's funny because I was concerned with the heat generated by the D03 as compared to the A30, which was confirmed by others in this thread.

I have a thermal scope that I used to verify my suspicions of the D03 producing more heat. After verifying that avenue, (I didn't take pictures of the thermal comparison, but it was extremely obvious) I decided to do an amperage draw test. I tested both integrated amps at their switched off state, and switched on idle state. See pictures. My findings again confirmed my suspicions. The D03 does not get dangerously hot, but it is very noticeable when comparing to the A30.

Others have asked about subwoofer pairing and I have some thoughts, but no measurements. I paired my 10" Klipsch subwoofer to both the D03 and A30. The D03 was much more pleasant to get properly paired. I never measured the output voltage of the sub connection on either, but I had to nearly turn the amp on the subwoofer all the way down with the A30. Any small increase in the gain knob on the sub resulted in obnoxious and almost uncontrollable output. The D03 was straightforward and seemed to have more linear control over the subwoofer. Neither have a lowpass filter that can be considered useful without further control via the subwoofer itself.

Subjective comments galore coming up. Overall the aesthetics of the A30 are far superior to the D03 in my opinion. Sound signatures are very similar, but I feel the D03 has greater midrange extension, where's the A30 has greater high end clarity. That higher clarity comes at a cost of sounding "digitized" to my ears. Both are great integrated amps though, and you can't go wrong with either.
 

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Toku

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I have been comparing the Aiyima D03 with the Loxjie A30 over the past week and ran across this thread in an attempt to help me make a decision. It's funny because I was concerned with the heat generated by the D03 as compared to the A30, which was confirmed by others in this thread.

I have a thermal scope that I used to verify my suspicions of the D03 producing more heat. After verifying that avenue, (I didn't take pictures of the thermal comparison, but it was extremely obvious) I decided to do an amperage draw test. I tested both integrated amps at their switched off state, and switched on idle state. See pictures. My findings again confirmed my suspicions. The D03 does not get dangerously hot, but it is very noticeable when comparing to the A30.

Others have asked about subwoofer pairing and I have some thoughts, but no measurements. I paired my 10" Klipsch subwoofer to both the D03 and A30. The D03 was much more pleasant to get properly paired. I never measured the output voltage of the sub connection on either, but I had to nearly turn the amp on the subwoofer all the way down with the A30. Any small increase in the gain knob on the sub resulted in obnoxious and almost uncontrollable output. The D03 was straightforward and seemed to have more linear control over the subwoofer. Neither have a lowpass filter that can be considered useful without further control via the subwoofer itself.

Subjective comments galore coming up. Overall the aesthetics of the A30 are far superior to the D03 in my opinion. Sound signatures are very similar, but I feel the D03 has greater midrange extension, where's the A30 has greater high end clarity. That higher clarity comes at a cost of sounding "digitized" to my ears. Both are great integrated amps though, and you can't go wrong with either.
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.
 

Schlippwhip68

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I have been comparing the Aiyima D03 with the Loxjie A30 over the past week and ran across this thread in an attempt to help me make a decision. It's funny because I was concerned with the heat generated by the D03 as compared to the A30, which was confirmed by others in this thread.

I have a thermal scope that I used to verify my suspicions of the D03 producing more heat. After verifying that avenue, (I didn't take pictures of the thermal comparison, but it was extremely obvious) I decided to do an amperage draw test. I tested both integrated amps at their switched off state, and switched on idle state. See pictures. My findings again confirmed my suspicions. The D03 does not get dangerously hot, but it is very noticeable when comparing to the A30.

Others have asked about subwoofer pairing and I have some thoughts, but no measurements. I paired my 10" Klipsch subwoofer to both the D03 and A30. The D03 was much more pleasant to get properly paired. I never measured the output voltage of the sub connection on either, but I had to nearly turn the amp on the subwoofer all the way down with the A30. Any small increase in the gain knob on the sub resulted in obnoxious and almost uncontrollable output. The D03 was straightforward and seemed to have more linear control over the subwoofer. Neither have a lowpass filter that can be considered useful without further control via the subwoofer itself.

Subjective comments galore coming up. Overall the aesthetics of the A30 are far superior to the D03 in my opinion. Sound signatures are very similar, but I feel the D03 has greater midrange extension, where's the A30 has greater high end clarity. That higher clarity comes at a cost of sounding "digitized" to my ears. Both are great integrated amps though, and you can't go wrong with either.
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!
 

Schlippwhip68

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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.
I ran my D03 for hours and while it was warm it was not never hot. I even repasted the chip with some expensive Austrian thermal paste to be extra cautious, probably OCD, but worth it.
 

Schlippwhip68

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For more info about output power you can read TAS5624 datasheet.
On figure 1 you can see about 2x70W 8Ohm and 2x115W 4Ohm with 36V supply voltage and 0.1% THD+N.
Reading figure 2 and 4 could be estimated about 2x55W 8Ohm and 2x90W 4Ohm with 32V supply voltage and 0.1% THD+N.
You also have to know 8Ohm power is limited by supply voltage but 4Ohm power is limited by supply ampere, it should be not less than 6A for full power.
With 5A should be a little bit less than maximum possible at 4Ohm.
That's all about power
...and in real time usage the D03 on my desk never really went past 11.00 oclock on the dial for volume.
 

Schlippwhip68

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OK so I got the D03 and tested it out with a few different speakers etc.

Everything sounded good/great out of this thing to my untrained ears. The Fluance RT82/ART DJ Pre II turntable into its RCA sounded pretty darn good to us (some have said it lacking). I wasn't able to AB it with a different amp but it sounded good enough for our untrained ears. Bluetooth sounded great as well. Of note, the build quality is a bit lame. Volume knob wobbles a bit when using it. The Bluetooth drops you when you aren't using it so you have to go and reconnect on the iPhone. This is actually pretty damn lame. I don't want to constantly have to make those clicks as its not just a short quick thing on my iPhone. BT range was good tho and it got plenty loud for us. Especially on the Klipsch R-51M's. I did like being able to adjust the input without the remote using the switches (wobbly) on the front. It was easy. Display light is kind of lame but the display is small so not bad.
I pulled my D03 apart to paste the chip and as far as those little plastic buttons go there is nothing to worry about. The do have a little play but believe or not they are actually quite solid underneath. They are not a fixed button so beware if you dismantle the unit but what they press is fixed and very well. The PCB board is very clean and well soldered.
 

rmerchant3

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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.
I had a feeling that was the case. Thank you for confirming.
 
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