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

[MaxwellsEq]

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?

Any oscillation at any frequency in an amplifier circuit is a failure. Full stop.

There's an engineering joke: "I tried to build an amplifier but accidentally built an oscillator. I then tried to build an oscillator, but accidentally built an amplifier".

 

[Guddu]

Guddu > are you a musician ?

Not professionally.

 

[daniboun]

Not professionally.

Nice I am a drummer ) I played in many bands

 

[daniboun]

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.

Hummm do you consider a Soic8 OP amp soldered into a DIP8 adapter as being a socketed op amp ?

 

[MaxwellsEq]

Hummm do you consider a Soic8 OP amp soldered into a DIP8 adapter as being a socketed op amp ?

Of course.

 

[daniboun]

@ICIETDIYEUR. / @Alexander Lin
Any reason to have updated the output caps from Gold Nichicon to Muse on final version ?

 

[Alexander Lin]

@ICIETDIYEUR. / @Alexander Lin
Any reason to have updated the output caps from Gold Nichicon to Muse on final version ?

Muse is non-polarized, while Gold Nichicon is polarized. For signal coupling, non-polarized is preferred.

 

[daniboun]

Hi amigos,
I took the time to test the D3 Pro this weekend.
Here's the dedicated setup:
O-Noorus D3 Pro Amplifier
Teufel T10 Active Subwoofer (32Hz @ +/-3dB)
The Alti Speakers (measurements here)

I had the pleasure of enjoying my playlist for several hours with a variety of audiophile tracks. First of all, I must admit that I was surprised that such a small amp has such comprehensive connectivity. The subwoofer control is really simple and seems well implemented.
Since I also own the Wiim Amp Pro and have extensive experience with the TPA3255 chips (see my Bamboo / Sylph Audio ASH-400 projects, etc.), I can therefore give you a fairly objective opinion.
From the first listen, I felt the TPA3255's distinctive, pleasant signature. In fact, it's so similar to the Wiim Amp Pro that if you close your eyes, I challenge you to tell them apart...
Alexander sent me a version with a 48V/5A GaN PSU, with the volume set to 45. This little amp is more than enough for my 50m² living room, considering it drives a 2.1 system with a powered subwoofer.
I tested it via the USB inputs and Bluetooth via the LDAC protocol. I mainly stream via BT and Wi-Fi. However, when the amp is connected via BT LDAC, nothing on its screen indicates that it's connected via this protocol, which is a bit of a shame... Regarding the design, I think it's hard to do better since this is a very complete Power DAC. I do, however, regret that the DC in (PSU) input is a little too close to the speaker terminals.

Overall, I am convinced of the quality of this D3 Pro even if objectively, I am eagerly awaiting the ASR test in particular to confirm its power and the good implementation of the PFFB circuit. The manufacturer was very transparent because he provided the complete measurements with the instructions upon purchase. It's rather a great guarantee of confidence! Thanks again to @Alexander Lin for his seriousness.

 

[gnat_leader]

reading this...

"enjoyed my playlist"
"pleasant signature... similar to Wiim"
"convinced of the quality"

uh... that's all???

Amigo, thanks for posting, but really...
can we not get more of a subjective opinion about how it sounds other than "sounds like the Wiim"?

edit: I'm also disappointed that everyone seems to use tiny bookshelf speakers when "testing" amps, but maybe that's just me.

 

[daniboun]

reading this...

"enjoyed my playlist"
"pleasant signature... similar to Wiim"
"convinced of the quality"

uh... that's all???

Amigo, thanks for posting, but really...
can we not get more of a subjective opinion about how it sounds other than "sounds like the Wiim"?

edit: I'm also disappointed that everyone seems to use tiny bookshelf speakers when "testing" amps, but maybe that's just me.

The ALti speakers are not tiny at all )) check here man : https://www.audiosciencereview.com/...-way-speakers-project-spinorama-inside.65436/

I will develop my arguments but I do not wish to fall into dithyrambic poetry in the style of "what hifi" or other hifi magazines.
That's why I went for a "tear down" rather than a subjective test that no one will give credence to.

BTW : I tried the D3 Pro with my Polk R700 and I could drive it without any problem as well. Still in the same living room.

There's a plethora of TPA3255s on the market today. With the D3 Pro, O-Noorus undoubtedly offers a very good, highly comprehensive TPA3255 with truly incredible value for money.
Perhaps you'll hear me explain why I'd stick with the Wiim Amp Pro over the D3 Pro?

 

[gnat_leader]

The ALti speakers are not tiny at all )) check here man : https://www.audiosciencereview.com/...-way-speakers-project-spinorama-inside.65436/

I will develop my arguments but I do not wish to fall into dithyrambic poetry in the style of "what hifi" or other hifi magazines.
That's why I went for a "tear down" rather than a subjective test that no one will give credence to.

BTW : I tried the D3 Pro with my Polk R700 and I could drive it without any problem as well. Still in the same living room.

There's a plethora of TPA3255s on the market today. With the D3 Pro, O-Noorus undoubtedly offers a very good, highly comprehensive TPA3255 with truly incredible value for money.
Perhaps you'll hear me explain why I'd stick with the Wiim Amp Pro over the D3 Pro?

yes those ARE small. If you can hold a speaker in the palm of one hand it's small.

The "able to drive Polk R700" is nice additional info. But, the word "drive" is again a very lacking way to describe something.
Even a random $10 TPA3116 chinese class-d amp board can do that. But how well does it do it? And does it sound good???

Then again if you're using a POWERED subwoofer to "test" an amp, the test is already flawed as you're not using the amp for reproducing the complete audible frequency range. You're not testing the amp's power/current/drive ability, slew-rate/quickness, power supply ability, etc. not to mention frequency balance and if it's reproducing at normal listening volumes without distortion, compression, sound-stage collapse, or other anomaly.

But I guess I should understand from the fact that instead of pointing me to a real review of the Polk speakers you pointed me to a bunch of charts.

If you didn't intend on giving your personal opinion of how this amp sounds
maybe you shouldn't have included in the title of this thread "and subjective test"

Why not develop your arguments (opinion?) and use whatever words/adjectives as you think yourself rather than caring at-all what other person or magazines do?

What "O-Noorus undoubtedly offers" as you say...
is precisely what we are all here reading this thread and attempting to determine.
But instead of demonstrating this, you merely proclaim it. This is meaningless for us readers.

if it sounds pretty much the same as every other TPA3255 amp (which I seriously doubt)
then we would have zero need to waste time reading this "subjective test"

btw, why not just call it a "review"?
Also I'm very glad about the teardown pics.
I really like those and they do help us guess what it might sound like - for me, the pics are better than graphs/charts.

 

[MaxwellsEq]

Also I'm very glad about the teardown pics.
I really like those and they do help us guess what it might sound like - for me, the pics are better than graphs/charts

How?

 

[gnat_leader]

How?

I can't interpret this question without more specifics.

 

[MaxwellsEq]

I can't interpret this question without more specifics.

Also I'm very glad about the teardown pics.
I really like those and they do help us guess what it might sound like - for me, the pics are better than graphs/charts

How can you decide what something will sound like from a teardown photo?

Please explain your methodology.

 

[gnat_leader]

How can you decide what something will sound like from a teardown photo?

Please explain your methodology.

I didn't say "decide" I said "guess" and for a reason.
The guess is based on seeing the quality of the components used (mostly) and the layout, attention to detail, solder/connection quality, etc.

 

[MaxwellsEq]

I didn't say "decide" I said "guess" and for a reason.
The guess is based on seeing the quality of the components used (mostly) and the layout, attention to detail, solder/connection quality, etc.

Unless components are poor or operating out of spec; and unless solder joints are poor, they shouldn't impact sound quality. They may impact longevity or sustained power (e.g. insufficient heat extraction).

 

[Guddu]

I didn't say "decide" I said "guess" and for a reason.
The guess is based on seeing the quality of the components used (mostly) and the layout, attention to detail, solder/connection quality, etc.

Please tell us what is your guess about this amplifier based on components/detailed etc you have seen.

 

[daniboun]

yes those ARE small. If you can hold a speaker in the palm of one hand it's small.

Will answer you with some more details later... But I need to answer this point now )))
You absolutely cant hold it on your hand lol.... It s bigger than the Polk R200 to give you an idea next to the SVS 1000 Pro Sub (12 inch) :

 

[Audionaut]

The ALti speakers are not tiny at all )) check here man

Thank you very much for your impressions of the D3 Pro.

But yes, of course, the Swan M5N with its 87 cm² membrane area is a small speaker. That's a little less than 180 cm² of membrane area for a stereo pair. Not much at all.
Unfortunately, I no longer own large speakers with 18-inch bass drivers, only active subwoofers. Two speakers with 18-inch bass drivers have a membrane area of approx. 2,400 cm², while my two 12-inch coaxial speakers offer a membrane area of approx. 1,150 cm².
So I temporarily connected the D3 without Pro to my 12" PA coaxial speakers from B&C, which worked very well, as was to be expected, since they have very good efficiency. I think that was essentially what gnat_leader's question or request was getting at: Are the small TPA 3255 chip amplifiers capable of driving large speakers with a large membrane area?
Yes, they are, provided that the power supply delivers a stable current. Actually, as with any cleanly designed amplifier. What many people overlook is that large speakers usually have better efficiency than small ones.
My suggestion, which of course always gets lost in the vastness of the forum because I am not a premium user with sufficient influence, is to always perform the tests on those amplifiers where this is possible, such as TPA 3255 amplifiers with external power supply input, always using the same power supplies and not the optional ones supplied, as these have a major influence on the measurement results.

 

[daniboun]

The small TPA 3255 chip amplifiers are

Can they drive large, large-diaphragm speakers? Yes, provided the power supply provides stable power. It's basically the same as with any well-designed amplifier. What many people forget is that larger speakers generally have better output than smaller ones.

Several of us have tested the TPA325X amps on larger speakers. I myself tested the Wiim Amp Pro and the D3 Pro on the Polk R700, which have a nominal impedance of 4R and a sensitivity of 88dB. I had no difficulty driving them and at a decent volume.

BTW