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Tournesol

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I'm new on this forum. I have a Power mosfet (Lateral) 250W CFA amp in project (DIY personal design) with some original features.
- As all CFA, high slew rate and extended loop bandwidth.
- But treated like a VFA on some aspects: high loop gain (>100dB) with optional error correction.
- Original DC servo.
- Inclusive compensation.
- Flat tempco on VAS.
- VERY low distortion levels on simulation.

I would like to know if it is the right place for such a project, if it can interest some people, if I have a chance, here, to get collaborative exchanges in a friendly atmosphere and help and suggestions of some other designers.
Thank in advance.
disto.png
 
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Tournesol

Tournesol

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Of course, dkinric. (thanks for your answer)
Before to start such a work, I want to be sure to not waste my (and others) time, bandwidth, and if this project can arouse some interest.
Too, after a bad experience in another forum, if it is welcome here to share subjective listening impressions without driving crazy troops of extremist objectivists on a mission. (My sound engineer side ;-)
It being understood that there is no question for me either of falling into reverse audiophile delusions which would leave on the battlefield smoking corpses of some verified laws of physics ;-)
 

dkinric

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My take is that sharing subjective impressions are fine as long as it is in the context of (in addition to, or based on) some kind of measurable results, and they are recognized as nothing more than your personal opinion, which others may or may not share.
The gist is that what you hear (or think you hear) in your room/conditions/equipment/innate bias'/mood/hearing frequency range/etc. may have very little correlation with others.
 
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Tournesol

Tournesol

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May-be not the good place to start a discussion between 'objectivists' and subjectivists' positions ? And i'm not interested in religion wars.
My take is the balance is in the middle. Subjective impressions are 'subjective", depending on culture, situations, mood, measurements are objective and better performing than ears BUT we don't know how to measure everything, specially in the micro dynamic domain, it is hard to translate measurements in feelings while everything that exists in the universe has a character. My EE education leads-me to measurements, but, my sound engineer career lead-me to share listening impressions and feelings: It seems to me reasonable to listen to music with my ears. rather than an oscilloscope ;-) Both are complementary, not opposite. I do not believe in any "Truth", and can only express "personal" points of vue that has no universal value.
Hence my questions about this forum politic.
 

Doodski

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I suggest give it a try here. There's different sorts of peeps here and sometimes it gets interesting. I suspect you will be :) There are designers here and you might hit it off with them.
 

SIY

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Of course, dkinric.
Too, after a bad experience in another forum, if it is welcome here to share subjective listening impressions without driving crazy troops of extremist objectivists on a mission.

If by "subjective" you mean "not using basic controls," this may not be a good place to do that. Doing things in a reality-based manner means controls, it means using double blind validation, it means data rather than make-believe.

If you want to base your work on actual science, this is the best place on the internet.
 
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Tournesol

Tournesol

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This is exactly the kind of reaction and debate that I want to avoid if I post a work of design in progress on a forum.

Because it is obvious that one cannot reach the simulated results that my screenshot shows (one among many others) without a minimum of knowledge of what you call "actual science".

Because, having nothing to sell, I'm not going to start making snake oil vials (what you call "Make believe"?) or want to be the target of such a suspicion.

Because, for me, participating in a witch hunt alongside fundamentalists of a new religion that would be called "science" is not part of my favorite sportive activities.

Once ideas have been materialized in the form of an assembly of components, optimized during numerous measurements, comes the listening phase on the bench. These listenings, attentive and careful, without which no valuable work can be accomplished, each designer is free to practice them in the way that best suits him.

As far as I'm concerned, I only use your famous 'LMDBT' in extreme cases and I can explain why. Knowing that listening is to be learned, just like measuring correctly: If a difference in "audible" rendering is so subtle that it requires this type of long and painful protocol, I consider that it is negligible and begin to look at the BOM prices. Others are free to venture into the maze of uncertainty.

So, may-be you are right, and better for me to find another forum ?
 
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sergeauckland

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An amplifier with the sort of low distortion numbers you mention, even without error correction, will be a Good Amplifier, and therefore worth discussing here. However, an amplifier of that sort won't have a 'sound' unless you deliberately engineer one. You don't show the frequency response, but flat to 1dB to 20kHz is trivially easy, so I can't imagine why your amplifier would be anything but transparent.

That being the case, any discussion of 'sound' is meaningless and pointless, as 'transparent' means transparent which means it'll pass any straight wire bypass test.

If you try and make claims for a 'sound', then I think you'll meet some resistance here. If you make claims for engineering excellence, you're likely to get support.

Anyway, looking forward to seeing more of your design.

S
 

dkinric

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Not sure what you are looking for here, pre-approval? I think if you are doing a build and have something interesting to share, post it in the proper forum. DIY builds can pretty interesting, especially if you have some type of measurements to share along with it, or it uses components with known qualities.
If your only proof of success is that even your SO came in from the kitchen to say how much better it sounds, you may need to be prepared for some skepticism.
 

Crazy_Nate

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I think this forum is fairly well behaved as forums go (especially audio). Sure, there's a lot of discourse over audio preferences, but there's a fairly strong emphasis on backing up what we can with measurements . I'm sure a design perspective would be appreciated, especially if transparency is a design goal of yours. :cool:

I doubt you'll get chased down by subjectivists here, but you can never predict what happens on the internet ;)
 

Xulonn

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If you can hear a "difference" only when you know in advance what you are listening to, and you cannot hear it when you don't know which of two components that you are listening to, elementary logic should tell you that the difference is not real, and that your brain is fooling you.

I agree with others that if you cannot accept the fact that science demands that we control our biases for a truly valid evaluation, this is not the forum for such a discussion. Insistence on double blind testing is not a religion or a cult - but hard science and logic. ASR is not a science forum, but rather a science-based forum.

Engineering (solving problems) is not science (discovery) [LINK], but is based on findings of science. Some engineers have a sound footing (pun intended) in science, and others can be great designers and problem solvers, yet be clueless about sciences other than the physics upon which their expertise is based.
 

pma

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Hi Tournesol,

nice to see you here.

1) Do you have a functional sample, or just a simulation, as seen in post #1?
2) Are you willing to share the schematics, or at least a simplified circuit scheme?

Regards,
 

BDWoody

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It seems to me reasonable to listen to music with my ears. rather than an oscilloscope

Right...and without any controls, whatever you may 'hear' doesn't have any particular meaning to anyone else...

Have you done an equivalent level of study in psychoacoustics as you have in EE? They aren't really related...lots of smart engineers buy (build?) snake oil garbage. Ignorance can be cured...
 

Xulonn

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I can't imagine why your amplifier would be anything but transparent.

Serge, I believe that, depending on how the amplifier "reacts" to the complex inductive load of a loudspeaker, there can indeed be differences in how an amplifier "sounds." It is also my understanding that inductive load reactions are a whole 'nuther arena of variables that are much more difficult to measure than simple specs under resistive load. Two amplifiers that measure similarly into a resistive load may sound completely different when driving difficult loudspeakers. And this would indeed show up under controlled ABx listening tests.

I am not an engineer, and would appreciate it if an ASR member who is an EE would confirm or correct my statements.
 
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MrGoodbits

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A DIY amp project really could achieve basic controls, at minimum a double-blind test, level-matched against a known good amplifier. As one engineers and tweaks the design, particularly in the early stages, you could indeed find audible differences that you can verify in DBT; at that point it's "safe" to characterize those differences subjectively, I think.
 

sergeauckland

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Serge, I believe that, depending on how the amplifier "reacts" to the complex inductive load of a loudspeaker, there can indeed be differences in how an amplifier "sounds." It is also my understanding that inductive load reactions are a whole 'nuther arena of variables that are much more difficult to measure than simple specs under resistive load. Two amplifiers that measure similarly into a resistive load may sound completely different when driving difficult loudspeakers. And this would indeed show up under controlled ABx listening tests.

I am not an engineer, and would appreciate it if an ASR member who is an EE would confirm or correct my statements.
If an amplifier is stable into any load, of any impedance, then its performance can be measured into as complex a load as you care to make. If then, the measured performance is good enough into any specified load, that amplifier still won't have a sound of its own.

It's only when an amplifier gets used outside of its design envelope that it can then be audible, but that's the sound of the amplifier being abused, not is normal operating conditions.

That's one further reason why listening tests MUST be done with rigour, or it's quite easy to give an amplifier a load it was never designed to operate into, then claim it doesn't sound as good as something else.

Having said that, it's hard these days to make an amplifier that isn't unconditionally stable into any reasonable (and unreasonable) load unless the designer is being deliberately obtuse and doing it for marketing reasons......this amplifier is so sensitive it'll show up cable differences lesser amps won't show......sure, it goes unstable whereas the 'lesser' amp doesn't!

S
 

Thomas savage

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This is exactly the kind of reaction and debate that I want to avoid if I post a work of design in progress on a forum.

Because it is obvious that one cannot reach the simulated results that my screenshot shows (one among many others) without a minimum of knowledge of what you call "actual science".

Because, having nothing to sell, I'm not going to start making snake oil vials (what you call "Make believe"?) or want to be the target of such a suspicion.

Because, for me, participating in a witch hunt alongside fundamentalists of a new religion that would be called "science" is not part of my favorite sportive activities.

Once ideas have been materialized in the form of an assembly of components, optimized during numerous measurements, comes the listening phase on the bench. These listenings, attentive and careful, without which no valuable work can be accomplished, each designer is free to practice them in the way that best suits him.

As far as I'm concerned, I only use your famous 'LMDBT' in extreme cases and I can explain why. Knowing that listening is to be learned, just like measuring correctly: If a difference in "audible" rendering is so subtle that it requires this type of long and painful protocol, I consider that it is negligible and begin to look at the BOM prices. Others are free to venture into the maze of uncertainty.

So, may-be you are right, and better for me to find another forum ?
Yes I'd say best you got elsewhere. This is a science and engineering based audio forum.

Iv no interest in seeing pages of back and forth regarding your subjective evaluations and design choices based on those .

It will just end up a argumentive mess .

Good luck on finding a new home, there's tons of places that value your approach so no point wasting time here.

Cheers
 
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Tournesol

Tournesol

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Iv no interest in seeing pages of back and forth regarding your subjective evaluations and design choices based on those .
Ok, thanks. That is exactly the answer I needed.
For the calculations and measurements, I have yet near all what I need on my computer and my bench.
Byby, sorry to have wasted your time.
 
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Xulonn

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Too, after a bad experience in another forum, if it is welcome here to share subjective listening impressions without driving crazy troops of extremist objectivists on a mission. (My sound engineer side ;-)

As long as you do not claim to hear differences that science tells us we cannot possibly hear, you can have a very productive exchange at ASR. If I am reading your graphs correctly, the distortion levels of your design might rival the very best amplifiers that have been tested so far by Amir. ASR regulars appreciate and respect excellent engineering, even if distortion and noise levels are well below human hearing thresholds.

Most of the regular posters here understand the subjective side of music recording, mixing, mastering and production. But we are also painfully aware that many sonic differences in audio components and systems claimed to be audible by audiophiles are not real.

We react negatively to claims that are known to be impossible based on repeated, confirmed scientific testing that has survived challenges and peer review. There is much in audio yet to be discovered, but like the hardcore scientific theories (such as gravity), it takes extraordinary evidence to support extraordinary claims.
 
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