O-Noorus D1 - TPA3255 PFFB Stereo Amplifier - Front Display, Tone Control (with bypass) and Remote

[FanatNsk]

Can you retest but now with all 4x 220p capacitors? It is my understanding that you only installed 2, right?

Look SPL for four capacitor 220pF at 4Om load

 

[ICIETDIYEUR]

Hello UAN

LM4562 is a bipolar type OPAMP, just like NE5532.
There is another reference at TI called LME49720 which is in fact a "renaming" of the LM4562.

NB: These are so-called "DUAL" OPAMP references

And since ASR readers are nice so I'll try to please you by presenting you with a table of very interesting OPAMPs that are also widely used on class D amplifiers that use the TPA3255 chip (although it is wiser to talk about the "topology" of the circuit used) ->

Sorry for the annotations in French on the board but it's my native language

However, these are very easily understandable

Regards.

 

[ICIETDIYEUR]

@ FanatNsk:

Thanks for this graph with a load of 4 Ohms with the modification

(Q: Are your measurements carried out on a pure resistive load or on speakers ?)

Can you make this measurement with a load of 8 Ohms because the TPA3255 in the typical Class D amplifier configurations are much more sensitive to it ?

@ UAN:

Is your FFT chart made with the 'MOD' ?

 

[UAN]

To ICIETDIYEUR​

These are the measurements of the original D1.
I don't have an opamp with JFET inputs right now, so I can't do the modification to the amp.
But I think that with the djifet we will not notice the difference in measuring nonlinear distortions.Mainly the TPA chip distorts.
But by ear there are improvements when replacing the op-amp.

 

[ICIETDIYEUR]

People hi

UAN, thank you for your information

You say that the TPA3255 deforms but maybe it's because it's 'badly fed'

(NB: I'll talk about this point when I'm decided -> )

FanatNsk, I think readers who follow this MOD with interest are eager to see your graph with an 8 Ohm load

Regards.

 

[ICIETDIYEUR]

FanatNsk.

If you publish your graph with an 8 Ohm load, I would let you know here a 'little secret' about the possibility of further improving the listening quality (also measurable to remain objective) with your amplifier which is valid for ALL amplifiers with a TPA3255 chip

Notice to interested readers: I propose here to encourage FanatNsk

Hurrah ! for FanatNsk

 

[ICIETDIYEUR]

People hi

As an introduction to my post I wanted to say that I hope that nothing has happened to FanatNsk since he no longer responds

Here, I'm going to try to explain something that many of you (including amplifier manufacturers who use the TI TPA3255 chip) didn't understand or probably misinterpreted.

To do this, I will refer to the user manual of the TI evaluation board (TEXAS INSTRUMENTS User's Guide for PCB TPA3255EVM).

So here is a part (the one we are interested in here) of the circuit page for the TPA3255 ->

So far, everyone knows and/or recognizes the components usually found on our PCBs.

But on page 20 of the manual there appears a 'detail' that people have not understood, ignored, forgotten, misinterpreted, in short left aside ->

Indeed, every time I ask the question on 'this subject', I get a whole bunch of answers from people more or less experienced in electronics, for example:

- "there are already large capacities of 2200F or 4700μF (depending on their PCB)" which is the answer I get almost all the time...

... but then why does TI show us this and moreover has never published a patch if this was the case ?

I think they think that everyone has understood, although they are not talking to people who have such a high level of mastery as themselves.

So yes, there are already large capacitors allowing the 'decoupling' of the power supplies necessary for the proper functioning of the TPA3255 chip, so I will try to explain to you what these are for because if TI has specified them in its DATASHEET it is because they serve 'something' !

We all use switching power supplies (SMPS) to power our Class D amplifiers for example and these have an output impedance.

This is an important notion for 'the future'.

The TPA3255 chip operates at very high frequencies (called PWM) generally between 450Hz and 600KHz depending on the different PCBs encountered most of the time.
It is easy to understand that this frequency must be as stable and 'clean' as possible to ensure the best possible operation of the TPA3255 chip.

And that's precisely where this 'little montage' comes in, which looks so insignificant in TI's DATASHEETS !

It is in fact a 'high frequency filter' in addition to the TI evaluation PCB but which can very well be implemented on our PCBs

The following images will help you better understand what I am saying and include the calculation formula for this filter ->

You will notice that I used a higher chemical capacity (470μF instead of 47F) but it doesn't matter because the 'cut-off' will be even lower although this capacitor takes up more space.
The 47μF indicated by TI is better indicated to allow thanks to its smaller size to 'slide' it for example under the PCB in a case, soldered with the other two (1μF and 10nF).

To finish and to better illustrate my words, I offer you some pictures of a 'DIY' class D amplifier that has been equipped with this 'device' ->

Now to your soldering irons, measuring devices and especially your ears !

NB: if TI engineers have planned these components, it is... that they are indispensable !

They have oscilloscopes and they know how to use them...

Regards.


PSU 1200W (52V/23A) ->

 

[FanatNsk]

Can you make this measurement with a load of 8 Ohms because the TPA3255 in the typical Class D amplifier configurations are much more sensitive to it ?

The frequency response measurement was made on a resistive load of 4/8 Ohm, I do not use an acoustic system for the test because it is too loud and unbearable sound.

This measurement is for a modification of four 220pF capacitors with an 8ohm load:

 

[ICIETDIYEUR]

Thank you vert much

(Just for information FanatNsk: what OPAMPS do you use in your amplifier?)

Probably the 'MOD' I proposed is not doing too badly...

It almost looks like a high-performance amplifier now

Don't forget that it has the PFFB: you can compare this curve with the AIYIMA A70 for example...

(but AMIR didn't put the graph for 8 Ohms, maybe an oversight ? )

Regards.

 

[FanatNsk]

(Just for information FanatNsk: what OPAMPS do you use in your amplifier?)
Don't forget that it has the PFFB: you can compare this curve with the AIYIMA A70 for example...

Measurements of O-noorus D1 are made on the operational amplifiers installed at the factory.
Here is a comparison of the frequency response graphs of the O-noorus D1 (load 8Om, white line, use NE5532) and Aiyima A70 (load 8Om, green line, use Muses02):

These are measurements with a 4 Ohm load (white line - Aiyima A70, green line - O-noorus D1):

 

[ICIETDIYEUR]

LOL

no comment...

Maybe we should make an AIYINOORUS A1 amplifier !

PS: I notice that for the moment no one has tested my second 'MOD' with the 'high frequency filter'...
... but maybe like the first 'MOD', it's useless

 

[FanatNsk]

LOL

White line O-noorus D1 4 cap 220pF 4Om, Green line O-noorus D1 4 cap 220pF 8Om
Blue line Topping PA5 II 8Om, Purple line Topping PA5 II 4Om (topping not sensitive to load, always the same line)

 

[ICIETDIYEUR]

Hello FanatNsk

Thank you for this new comparison ->

Personally I find that once the 'MOD' is in place, the O-NOORUS D1 amplifier 'competes' rather well compared to the AIYIMA A70 and the TOPPING PA5 which are reputed, well-known brands and whose two models are among the best devices in the ranking made by AMIR

This proves to us that the young company O-NOORUS is capable of making very good devices and that they do not lack much to offer in the very near future devices capable of taking the 'path of exceptionality'...
... The future will tell

 

[ICIETDIYEUR]

People hi

@ FanatNsk:

Could you make the same graph as the comparison O-NOORUS D1 with 'MOD' and TOPPING PA5 with the AIYIMA A70 (i.e. 4 'curves' on the same table) please ?

Regards

 

[FanatNsk]

Could you make the same graph as the comparison O-NOORUS D1 with 'MOD' and TOPPING PA5 with the AIYIMA A70 (i.e. 4 'curves' on the same table) please ?

Topping PA5 II: White line 8Om, Light green line 4Om
Aiyima A70: Light blue line 8Om, Purple line 4Om
Fosi ZA3: Pale pink line 4Om, Dark green line 8Om
O-noorus D1 4xcap220pF: Dark blue line 4Om, Dark cherry line 8Om

 

[ICIETDIYEUR]

TOP !

 

[Robertosimus]

I have heard about few of their products in pipeline and their ideas are really good, don't know how big are they or their team but they aren't short on talent for sure.
- D2: DAC with TPA3255 PFFB amplifier, front digital display and subwoofer out, digital tone controls with bypass mode, probably remote as well
- D4: AKM DAC with TPS3255 PFFB amplifier, front digital display with ARC input and subwoofer out, digital tone controls with bypass mode, probably remote as well - Quite a complete package in my view
- A Dual-mono TPA3255 amplifier with PFFB topology, analog inputs
-and probably more.....

I emailed them asking for the new products releases.

This is the reply:
In December 2024, D4 will be released. D4 has Bluetooth, optical fiber, coaxial, USB, U disk, HDMI ARC, RCA. Supports TREBLE, MIDDLE, BASS adjustable.
With bypass and tone optional. TPA3255 PFFB stereo, subwoofer output,

In January 2025, D3 PRO will be released. D3 PRO has Bluetooth, optical fiber, coaxial, USB, U disk, HDMI ARC, RCA. Supports TREBLE, BASS adjustable.
TPA3255 PFFB stereo, subwoofer output, DAC: AK4493 USB: XU316 Bluetooth: qcc3084, supports LDAC, APTX-HD, etc.

In addition, D6, D2, and D5 have been developed.

 

[ICIETDIYEUR]

People hi

I can also specify that these two models integrate the same principle as my 'MOD' presented for the D1

regards.

 

[Robertosimus]

People hi

I can also specify that these two models integrate the same principle as my 'MOD' presented for the D1

regards.

Did they also do something about the mediocre solder quality? There are so many reviews about people receiving defective product because of loose solderings.

 

[ICIETDIYEUR]

For my part, I have NEVER encountered this type of problem with my D1 copy.