O-NOORUS D3 PRO : Tear Down and subjective test (in progress)

[daniboun]

Hi Amigos,

To my great surprise, I received a sample of the Onoorus D3 Pro this morning. BTW a BIG thanks to @Alexander Lin for keeping his promise )
I'll take the time to test it next week to compare it to my Wiim Amp Pro.
In the meantime, here's a teardown of the D3 Pro with a procedure for disassembling it (for OP amps rolling)

I see that Alexander didn't do things by halves since he shipped me a USB cooler to accommodate the D3 pro. I also got a 48V/5A GaN brick PSU.
We can see that the D3 Pro has a large passive heatsink that covers almost the entire PCB

In this first shot, we see that the D3 Pro is equipped with 3 OP amps 1656 in DIP8 (one dedicated for the SUB I guess)
Omron relays and Nichicon caps are observed

In this second shot, we can see that its designer opted for shielded Inductors with flat wire
Which is rather a guarantee of quality
We can also see the BT QCC3084 chip at the bottom left

Here is a close-up of the OPA1656

As I mentioned, I will come back to you with my impressions regarding the audio experience. Regarding the design, I find it rather well made and very compact. The connectivity is complete even if I find that the DC input is a little too close to the speaker terminals.
The packaging is also good and the user manual shows the full audio measurements (now just have to wait for the ASR test to see if they match). You can see them online here

 

[daniboun]

I forgot to share, to follow the evolution in its design....
It seems that some caps choice has been revised

 

[Guddu]

Hi Amigos,

To my great surprise, I received a sample of the Onoorus D3 Pro this morning. BTW a BIG thanks to @Alexander Lin for keeping his promise )
I'll take the time to test it next week to compare it to my Wiim Amp Pro.
In the meantime, here's a teardown of the D3 Pro with a procedure for disassembling it (for OP amps rolling)

I see that Alexander didn't do things by halves since he shipped me a USB cooler to accommodate the D3 pro. I also got a 48V/5A GaN brick PSU.
We can see that the D3 Pro has a large passive heatsink that covers almost the entire PCB



View attachment 474026View attachment 474027


View attachment 474028
View attachment 474029
View attachment 474030
View attachment 474032

In this first shot, we see that the D3 Pro is equipped with 3 OP amps 1656 in DIP8 (one dedicated for the SUB I guess)
Omron relays and Nichicon caps are observed

View attachment 474034


In this second shot, we can see that its designer opted for shielded Inductors with flat wire
Which is rather a guarantee of quality
We can also see the BT QCC3084 chip at the bottom left


View attachment 474035


Here is a close-up of the OPA1656

View attachment 474037


As I mentioned, I will come back to you with my impressions regarding the audio experience. Regarding the design, I find it rather well made and very compact. The connectivity is complete even if I find that the DC input is a little too close to the speaker terminals.
The packaging is also good and the user manual shows the full audio measurements (now just have to wait for the ASR test to see if they match). You can see them online here

Looks very well. Now that you have it opened already, let me ask you a few things:
- What's the size of metal heatsink/radiator slapping the tpa3255 chip? Do you have a pic or can get a pic?
- Is there enough space inside for discrete opamps like Sparkos etc. if swapped?

 

[daniboun]

Looks very well. Now that you have it opened already, let me ask you a few things:
- What's the size of metal heatsink/radiator slapping the tpa3255 chip? Do you have a pic or can get a pic?
- Is there enough space inside for discrete opamps like Sparkos etc. if swapped?

As I said, the heatsink covers about 3/4 of the PCB, here is a cut-out view. It measures approximately 10X10.5cm
Regarding OP amps, there is about 0.7mm of height left above the cover. This should work with most OP amps.

 

[daniboun]

Here are some more pictures deeper into the visual field
We see the Nichicon MUSE updated caps and Gold caps

 

[Guddu]

As I said, the heatsink covers about 3/4 of the PCB, here is a cut-out view. It measures approximately 10X10.5cm

This is good.

Regarding OP amps, there is about 0.7mm of height left above the cover. This should work with most OP amps.

I guess it will fall short on a few options for sure, specially stacked discrete opamps but still single chip type opamps shouldn't be an issue.

Thanks

 

[daniboun]

I guess it will fall short on a few options for sure, specially stacked discrete opamps but still single chip type opamps shouldn't be an issue.

Knowing that Amir has already demonstrated the almost useless interest of updating the OP amps.... the D3 Pro already has the very good OPA1656, no need to change )

 

[Guddu]

Knowing that Amir has already demonstrated the almost useless interest of updating the OP amps.... the D3 Pro already has the very good OPA1656, no need to change )

I know but curious ones won’t stop.

+designer provided socketed opamps, nothing wrong in capturing wider userbase.

 

[daniboun]

Next step :

I will test the O-noorus D3 Pro as soon as possible with my latest project : Alti MTG speakers, whose measurements are ultra linear.
By the way, for those who are interested,checkout :

'The Alti BookShell 2 Way speakers project. Spinorama Inside.'

Aug 29, 2025

FULL PROJECT FILE

Hello amigos,
I wanted to share with the ASR community a small DIY project for 2-way bookshelf speakers based on the "The AlTi" project by Matt Grant. These speakers were measured on Spinorama (see below) and offer a very interesting quality / price / performance ratio.

I didn't want to break the bank, so I was looking for compact, high-performance speakers with excellent measurements.
For those who would also like to give it a try, this project requires intermediate DIY skills and some soldering skills.

I originally set out to build the speaker cabinets...

• daniboun
• Replies: 9
• Forum: DIY Audio Forum

• 

 

[gnat_leader]

Knowing that Amir has already demonstrated the almost useless interest of updating the OP amps.... the D3 Pro already has the very good OPA1656, no need to change )

Amir's opinion aside, if it sounded the same as the NE5532 (as the anti-op-rolling crew say) then the designer would have had no need to use the OPA1656 in the circuit/product. The two op-amps are indeed different in design and spec's so it's no surprise that they could and probably do sound different in many circuits they are placed in. It seems logical to me that they could sound different in SOME implementations/circuits and then not in OTHERS, also depending on the rest of the playback chain.

PS. somebody check the data in the table this is what Perplexity told me. I'm assuming it's fairly correct.

 

[Mike123]

The OPA1656 has an output current of 100 mA instead of 10mA. These are very high-current op amps that work great in I/U DAC units and buffer inputs of class D amplifiers.

 

[daniboun]

Amir's opinion aside, if it sounded the same as the NE5532 (as the anti-op-rolling crew say) then the designer would have had no need to use the OPA1656 in the circuit/product. The two op-amps are indeed different in design and spec's so it's no surprise that they could and probably do sound different in many circuits they are placed in. It seems logical to me that they could sound different in SOME implementations/circuits and then not in OTHERS, also depending on the rest of the playback chain.

PS. somebody check the data in the table this is what Perplexity told me. I'm assuming it's fairly correct.
View attachment 474108

This has already been discussed many times...

'Does Op-amp Rolling Work?'

Mar 16, 2025

When I post my last video on review of Douk A5 amplifier, I mentioned that rolling (changing) op-amp ICs in there is fruitless. I got have a dozen comments under that video in youtube asking why so I thought I experiment again with the A5. Note that I have done the same testing with both DACs and Power Amplifiers and found the change to not make a difference. But let's see if the results are different this time.

The Douk A5 makes this job both easy and hard. It is easy because you can just lift the plexiglass and replace the op-amps. The difficulty was...

• amirm
• Replies: 959
• Forum: Stereo and Multichannel Amplifier Reviews

• 

 

[gnat_leader]

This has already been discussed many times...

'Does Op-amp Rolling Work?'

Mar 16, 2025

When I post my last video on review of Douk A5 amplifier, I mentioned that rolling (changing) op-amp ICs in there is fruitless. I got have a dozen comments under that video in youtube asking why so I thought I experiment again with the A5. Note that I have done the same testing with both DACs and Power Amplifiers and found the change to not make a difference. But let's see if the results are different this time.

The Douk A5 makes this job both easy and hard. It is easy because you can just lift the plexiglass and replace the op-amps. The difficulty was...

• amirm
• Replies: 959
• Forum: Stereo and Multichannel Amplifier Reviews

• 

I already saw it and am fully aware. It doesn't prove anything IMO. And it doesn't address the fact that the chip designs are physically and testably different given by the manufacturers' design and performance spec's.

Also it doesn't address the logical question in the case of this O-Noorus D3 Pro amp why the designer chose to use this chip versus the ubiquitous other. So are we to assume the designer made this choice just because they look different and/or for marketing purposes (ie, because it's a newer chip buyers will automatically assume it's better)?

Anyway, not to start up the argument yet again. Let's move on. Looking forward to your test results

 

[daniboun]

edit: also it doesn't address the logical question in the case of this amp why the designer chose to use this chip versus the ubiquitous other. So are we to assume the designer made this choice just because they look different and/or for marketing purposes (ie, because it's a newer chip buyers will automatically assume it's better)?

Since I am not the designer I guess @Alexander Lin could answer....

 

[MaxwellsEq]

So are we to assume the designer made this choice just because they look different and/or for marketing purposes (ie, because it's a newer chip buyers will automatically assume it's better)?

5532/5534 are old and cheap. Despite thinking these are fine op-amps, if I was to sell a product, I'd probably use more recent and expensive op-amps. Consumers believe in constant improvement (think clothes-washing commercials) and so using old and cheap (but adequate) components is probably a bad idea commercially.

I'm more nervous about op-amp sockets. In my experience, they add noise and distortion (especially after a couple of swaps) which can swamp the miniscule differences between devices. I used them once on a prototype and had to abandon them and solder instead to avoid RF oscillation and in-band noise.

 

[daniboun]

I'm more nervous about op-amp sockets. In my experience, they add noise and distortion (especially after a couple of swaps) which can swamp the miniscule differences between devices. I used them once on a prototype and had to abandon them and solder instead to avoid RF oscillation and in-band noise.

I think this won't be too much of a problem in 2025, as soldering techniques have evolved considerably. It would be interesting to compare the noise from a SOIC8 and DIP8 sockets, but I doubt there would be a difference...

 

[gnat_leader]

I used them once on a prototype and had to abandon them and solder instead to avoid RF oscillation and in-band noise.

wow, you observed this in measurements? I'm very surprised by this.
and this oscillation was within a range that could be heard in an audio circuit? Or just visible by testing/measuring equipment?
I mean, the frequency was in a range that could affect an audio amplifier?

 

[Guddu]

5532/5534 are old and cheap. Despite thinking these are fine op-amps, if I was to sell a product, I'd probably use more recent and expensive op-amps. Consumers believe in constant improvement (think clothes-washing commercials) and so using old and cheap (but adequate) components is probably a bad idea commercially.

I am with you on this, but still would wonder if someone should really be concerned as long as components works together very well to provide intended results!
After all how many times we really look under the hood for our electronic/electrical components like that!

I'm more nervous about op-amp sockets. In my experience, they add noise and distortion (especially after a couple of swaps) which can swamp the miniscule differences between devices. I used them once on a prototype and had to abandon them and solder instead to avoid RF oscillation and in-band noise.

I think this won't be too much of a problem in 2025, as soldering techniques have evolved considerably. It would be interesting to compare the noise from a SOIC8 and DIP8 sockets, but I doubt there would be a difference...

Few months back I had a failure and someone more knowledgeable and experienced told me it could very well be because of the DIP8 socket. But this is just one off case with me out of many amplifiers I have (and have had in past) with DIP8 socket without any such issues.
Positively, it does gives you option to change opamp atleast if there is opamp failure or something with opamp.
However I would consider soldered opamp as safest option avoiding any loose component error or something similar.

 

[daniboun]

I am with you on this, but still would wonder if someone should really be concerned as long as components works together very well to provide intended results!
After all how many times we really look under the hood for our electronic/electrical components like that!



Few months back I had a failure and someone more knowledgeable and experienced told me it could very well be because of the DIP8 socket. But this is just one off case with me out of many amplifiers I have (and have had in past) with DIP8 socket without any such issues.
Positively, it does gives you option to change opamp atleast if there is opamp failure or something with opamp.
However I would consider soldered opamp as safest option avoiding any loose component error or something similar.

flexibility or security, that is the question) Well, we can debate philosophy one day lol
Guddu > are you a musician ?

 

[MaxwellsEq]

I think this won't be too much of a problem in 2025, as soldering techniques have evolved considerably. It would be interesting to compare the noise from a SOIC8 and DIP8 sockets, but I doubt there would be a difference...

I was not sufficiently clear - this is a weakness with socketed op-amps, not soldering.

I was prototyping a high gain amplifier and used sockets to swap between two different op-amps (with different characteristics which were significant at the gain and bandwidth I was seeking). After a few swaps I started measuring increased noise when there should have been no increase. On one of the op-amps I started getting an RF resonance. I removed the socket and soldered the op-amp onto the PCB and the noise returned to normal.