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O-NOORUS D3 PRO : Tear Down and subjective test (in progress)
Audionaut
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Sorry
I've changed it
OP
daniboun
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- #43
I wanted to reply to this message and sorry for the delay Guddu )
I'm going to try an approach that I suggested to @amirm by completely bypassing the OP Amps via a "Ghost OP amp" I'll let you know after the test )
As you will have understood, it is to attack the TPA3255 chip directly
Guddu
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daniboun. Can I offer my thanks for your contributions in the 3255 DIY amp arena. You directly got me into this and it has been very enjoyable. As I now have amplifiers that meet my limited needs I shall probably move on.
Can I also congratulate you on your ability to not snap at some of the, at best, poorly worded responses to your efforts.
Symptomatic of the World we live in I guess. You are a better man than me!
Thank you again.
Can I also congratulate you on your ability to not snap at some of the, at best, poorly worded responses to your efforts.
Symptomatic of the World we live in I guess. You are a better man than me!
Thank you again.
gnat_leader
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No that wasn't my question/comment.
I know any TPA3255 amp can drive most large and sensitive speakers with ease.
My interest is in how they sound doing it. As I would hope is the same for most readers.
Ie, a subjective opinion (review) with more "serious" floorstanding speakers and not bookshelf/desktop speakers like 95% of all other class-d amp reviews.
gnat_leader
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is this just for pure curiosity? I'm not a circuit expert but I wonder if this is wise to operate the device not as SMSL designed it to be used.
At the least you could be under-driving the 3255 amp chip. At worst?... I don't know could you break/burn something?
And the test/measurements you'd get from this, how would they be useful?
gnat_leader
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It looks pretty from what I can see not having it in front of me.
I would guess it'd sound pretty good, but you never know. That's what reviews and opinions are for.
gnat_leader
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some info I found about the chips used, via search, so don't kill me if some of it is incorrect.
I am comparing to the Aiyima A80 Pro which is what about $40 or $50 cheaper? Maybe not the best choice to compare but first one that came to mind.
I will try to delete or edit any info that's wrong. These are the supposed/reported features of the chips, not all of which the amps might be using.
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ICIETDIYEUR
Addicted to Fun and Learning
People hi 
Here is another image but this time of the complete prototype which served as a test before the final version although this prototype had already undergone numerous modifications ->
Danyboun, I really don't understand the point of wanting to use "Ghost OP amps" instead of those mounted in the device and let me explain:
- the amplifier originally has an A-F mode which allows 'somehow' (I'll explain later) to attack the amplifier via a source or a preamplifier.
- explanation: the OPAMPS mounted on this device were selected after comparative measurements and tests using a specific audio device that you may not have (I will not develop the rest).
- the OPAMPS but especially the circuit which makes up the feedback loop (especially the capacitor) have a DIRECT influence on the shape of the signal obtained at the output of the TPA3255 with its PFFB circuit.
The analysis of a Bode diagram made it possible to determine the value of the capacitor in order to obtain the best compromise according to the load used thanks to the PFFB circuit: what do you think will happen to the signal if you 'bypass' (therefore 'shunt' at the same time) the circuit used by the OPAMP in question?
At best you will be lucky, at worst you will obtain, for this very specific case, what some call a very real cognitive bias in certain conditions and therefore you will be self-satisfied with your modification.
Although a trained technician, logical and objective, I am also a fervent follower of listening tests (subjective) which may seem curious if we base ourselves on my first statement, however for me one does not go without the other since in the end this is indeed the goal sought with such a device: the 'SQ'
Unfortunately there is no device (yet?) capable of quantifying and therefore measuring the 'SQ'...
Here is another image but this time of the complete prototype which served as a test before the final version although this prototype had already undergone numerous modifications ->
Danyboun, I really don't understand the point of wanting to use "Ghost OP amps" instead of those mounted in the device and let me explain:
- the amplifier originally has an A-F mode which allows 'somehow' (I'll explain later) to attack the amplifier via a source or a preamplifier.
- explanation: the OPAMPS mounted on this device were selected after comparative measurements and tests using a specific audio device that you may not have (I will not develop the rest).
- the OPAMPS but especially the circuit which makes up the feedback loop (especially the capacitor) have a DIRECT influence on the shape of the signal obtained at the output of the TPA3255 with its PFFB circuit.
The analysis of a Bode diagram made it possible to determine the value of the capacitor in order to obtain the best compromise according to the load used thanks to the PFFB circuit: what do you think will happen to the signal if you 'bypass' (therefore 'shunt' at the same time) the circuit used by the OPAMP in question?
At best you will be lucky, at worst you will obtain, for this very specific case, what some call a very real cognitive bias in certain conditions and therefore you will be self-satisfied with your modification.
Although a trained technician, logical and objective, I am also a fervent follower of listening tests (subjective) which may seem curious if we base ourselves on my first statement, however for me one does not go without the other since in the end this is indeed the goal sought with such a device: the 'SQ'
Unfortunately there is no device (yet?) capable of quantifying and therefore measuring the 'SQ'...
gnat_leader
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100%. Unless this site is more about studying electronics and audio circuits, as apposed to audio (music!) playback systems.
My take is this site is focused more on the electronics side of things than the music. Which is fine.
But I think many site visitors/readers don't understand that or it's implications when they use the data to sway their purchasing decisions.
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Geert
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Lots of people involved in music production and/or playing a music instrument on this site.
OP
daniboun
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- Thread Starter
- #57
I wanted to ask you, I assume you have the prototype and also the final version? Have you noticed any differences between the two?
Since I highlighted that some components have been upgraded, I'm still curious ) BTW is the measured version the prototyped one or the final version?
ICIETDIYEUR
Addicted to Fun and Learning
Re 'dani'
The measured version is that of the final (marketed) version.
Regarding your first question I would answer no.
I have the original diagrams from the prototype version as well as all of its developments/modifications following discussions with ALEXANDER.
So ALEXANDER is the only one who could answer you.
For my part, I have only suggested or proposed 'solutions' (often known but adapted) which are based on my experiences and my personal knowledge:
it is ALEXANDER who makes the entire device from its prototype version that he imagined, I am only an enthusiast (just like him) who seeks to progress and find solutions in line with the expectations of the customers of which I am a part.
I am just satisfied that some of my ideas and/or proposals were retained by ALEXANDER when he found them relevant after, of course, having validated them through measurements but also through listening, even if I shouldn't say it to offend anyone but it is so.
On this subject, I doubt that, even if it is interesting from a commercial point of view, that engineers and/or managers of TOPPING or SMSL (to name but a few) will offer for sale on the market a 'purely theoretical' device which has only been 'validated' with measurements.
Also, I would like to have the opinion of Bruno Putzeys who has a verbal approach (and especially intellect and knowledge) if he were to read us here.
This would allow us to have a relevant opinion which would avoid certain 'slippages' of members (of which I may be one) which are quite unpleasant on a site as serious as this one.
The measured version is that of the final (marketed) version.
Regarding your first question I would answer no.
I have the original diagrams from the prototype version as well as all of its developments/modifications following discussions with ALEXANDER.
So ALEXANDER is the only one who could answer you.
For my part, I have only suggested or proposed 'solutions' (often known but adapted) which are based on my experiences and my personal knowledge:
it is ALEXANDER who makes the entire device from its prototype version that he imagined, I am only an enthusiast (just like him) who seeks to progress and find solutions in line with the expectations of the customers of which I am a part.
I am just satisfied that some of my ideas and/or proposals were retained by ALEXANDER when he found them relevant after, of course, having validated them through measurements but also through listening, even if I shouldn't say it to offend anyone but it is so.
On this subject, I doubt that, even if it is interesting from a commercial point of view, that engineers and/or managers of TOPPING or SMSL (to name but a few) will offer for sale on the market a 'purely theoretical' device which has only been 'validated' with measurements.
Also, I would like to have the opinion of Bruno Putzeys who has a verbal approach (and especially intellect and knowledge) if he were to read us here.
This would allow us to have a relevant opinion which would avoid certain 'slippages' of members (of which I may be one) which are quite unpleasant on a site as serious as this one.
OP
daniboun
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- Thread Starter
- #59
Thanks. Perfectly clear )Re 'dani'
The measured version is that of the final (marketed) version.
Regarding your first question I would answer no.
I have the original diagrams from the prototype version as well as all of its developments/modifications following discussions with ALEXANDER.
So ALEXANDER is the only one who could answer you.
For my part, I have only suggested or proposed 'solutions' (often known but adapted) which are based on my experiences and my personal knowledge:
it is ALEXANDER who makes the entire device from its prototype version that he imagined, I am only an enthusiast (just like him) who seeks to progress and find solutions in line with the expectations of the customers of which I am a part.
I am just satisfied that some of my ideas and/or proposals were retained by ALEXANDER when he found them relevant after, of course, having validated them through measurements but also through listening, even if I shouldn't say it to offend anyone but it is so.
On this subject, I doubt that, even if it is interesting from a commercial point of view, that engineers and/or managers of TOPPING or SMSL (to name but a few) will offer for sale on the market a 'purely theoretical' device which has only been 'validated' with measurements.
Also, I would like to have the opinion of Bruno Putzeys who has a verbal approach (and especially intellect and knowledge) if he were to read us here.
This would allow us to have a relevant opinion which would avoid certain 'slippages' of members (of which I may be one) which are quite unpleasant on a site as serious as this one.
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