About SMART ( Specific, Measurable, Achievable, Realistic and Time-bound), to rely at 100% on the "objective" point of view is both anti scientific, naive and, on my point of view as stupid as denying-it totally.
And for sure the best way to forbid any progress and discover anything new.
We can rely on what we know, but we know a little part of everything.
Universe is constituted of know matter and X5 its mass of an unknown one(s), that some call "Black matter". This is just an example.
Some phenomenas are not measurable, it is not the prove they don't exists when we can listen to them.
Like for the music our systems attempt to reproduce, designing an audio device REQUIRE both modesty and talent (sensitivity), a mix of measurements and listening ability: Listening experience is the only 'objective' tool, because it is THE GOAL. Even if this tool is hard to manipulate and share ;-)
Computers don't have modesty and talent. They are not appropriated to design good audio equipments.
As far i'm in concern, i'm equally bothered with objectivist's self-deception and snake oil vendors.
And for sure the best way to forbid any progress and discover anything new.
We can rely on what we know, but we know a little part of everything.
Universe is constituted of know matter and X5 its mass of an unknown one(s), that some call "Black matter". This is just an example.
Some phenomenas are not measurable, it is not the prove they don't exists when we can listen to them.
Like for the music our systems attempt to reproduce, designing an audio device REQUIRE both modesty and talent (sensitivity), a mix of measurements and listening ability: Listening experience is the only 'objective' tool, because it is THE GOAL. Even if this tool is hard to manipulate and share ;-)
Computers don't have modesty and talent. They are not appropriated to design good audio equipments.
As far i'm in concern, i'm equally bothered with objectivist's self-deception and snake oil vendors.
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The disk brake is a good example of something presumably simpler that works better, I agree. We can always find examples on both sides, and that is why it is unwise to overly generalize. Of course, I guess you would say I'm "over generalizing" by saying without qualification that it is unwise to overly generalize
. Let's just quit the semantic game-playng.Cheers,
Bob
Why? I just tried to simulate it, and that works with no problems.
The picture shows 1uV in and more then 120dB gain (more then 100dB at 20k), the output voltage has a large offset (this is part of the distortion) but still it shows about -40dB for the 1st harmonic.
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It is important that neither side in a discussion like this veer to one extreme. It is not helpful, in my opinion, to be either purely objective or purely subjective. Someone who builds an amplifier and makes no measurements and just listens is too far in the subjective camp. Similarly, someone who builds an amp, measures it and never listens to it is too far into the objective camp.
We all need to recognize that measurements play an important role, but that there are things that affect the sound that we don't measure or can't measure that also affect the sound.
Cheers,
Bob
We are on the same wave lengths
I wonder why so little efforts are done to extend our measurements tools.
How many of us have systems to sample and compare same *musical* samples from two sources ? Where are the programs to analyses their differences and isolate valuable datas from them ?
We are still measuring continuous signals, while we listen to transients (music) ;-)
Not sure if you are fully understanding the multi-tanh principle, a peek at Barrie Gilbert's classic paper would definitely help. It's not about gain, but about linearizing the transconductance over a given input domain.
The multi-tanh principle is overly sensitive to device matching and ratios. To add insult to injury, it's also very sensitive to temperature and needs PTAT current sources. This will make any practical discrete implementation pretty hairy and hard to harness. It would certainly horrify the "simple is better" disciples. BTW, I think AD8099 uses the multi-tanh principle as well.
The best I can think of is to go for the THAT Corp. quad devices.
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Hello Bob!
Hello Wali!
The fact that the overall NFB is not conducive to proper sound reproduction , many developers have realized more than 40 years ago. Even then began to appear such as amplifiers Denon PMA- 757 , Denon PMA-700v, Denon POA- 2000 , Denon POA- 3000 , Denon POA- 6600, Nakamichi PA5, Nakamichi PA7, Nakamichi TA2, Sony TA-N902 and others. He was later developed by The End Millenium. The company Lamm also makes transistor amplifiers exclusively without general NFB . This is to ensure that those who understand the sound , do not rely on the number of zeros after the decimal point in the coefficient of nonlinear distortions in the amplifier to an active load.
My good friend, sound engineer worked all his life , is now retired and enjoys designing amplifiers. He also came to that conclusion. Those who have ever listened to a quality amplifier with no overall NFB immediately fall in love with its sound.
regards
Petr
Hello Wali!
The fact that the overall NFB is not conducive to proper sound reproduction , many developers have realized more than 40 years ago. Even then began to appear such as amplifiers Denon PMA- 757 , Denon PMA-700v, Denon POA- 2000 , Denon POA- 3000 , Denon POA- 6600, Nakamichi PA5, Nakamichi PA7, Nakamichi TA2, Sony TA-N902 and others. He was later developed by The End Millenium. The company Lamm also makes transistor amplifiers exclusively without general NFB . This is to ensure that those who understand the sound , do not rely on the number of zeros after the decimal point in the coefficient of nonlinear distortions in the amplifier to an active load.
My good friend, sound engineer worked all his life , is now retired and enjoys designing amplifiers. He also came to that conclusion. Those who have ever listened to a quality amplifier with no overall NFB immediately fall in love with its sound.
regards
Petr
Wally, I can understand that, but I was pretty amazed by the fact that this simulation gives -40dB on 1st harmonic at 120dB gain and no FB. I took this as an indication that it could work as stated (in the patent). Any way, I thought that it would be of interest (to myself) to try the simulation, and I thought that the result was interesting. I will study the paper a bit more, and try to find some more info on the subject
Common mode linearized input stage and amplifier topology US 6963244 B1
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There is a third approach.
IM not so HO, a Listening Test is a MEASUREMENT. The measuring instrument is your Listening Panel. Like any measurement or instrument, it has an accuracy that you need to be aware of and check from time to time. The same goes for your instrument and its calibration.
If your Listening Test isn't Double Blind bla bla, its accuracy is suspect. If your listening test panel includes Golden Pinnae that can't return consistent results in DBLT etc you are using a piece of liquid BS to measure length.
A single person's preference (subjective opinion) isn't objective data. But the consistent preference of a reliable group of people IS. I'm usually after objective 'subjective' data like this in my listening tests eg which amp is preferred bla bla.
But I use exactly the same techniques to determine if a difference is reliably audible (capacitors/dither/phase/bla bla). In fact if the difference ISN'T reliably detected by at least some people, it is useless asking for preference. And you listen ONLY to those who return consistent results.
For da others, like deaf Golden Pinnae audio reviewers, you just polish your 'Virgins & Unobtainium' story and tell it very loudly. Some famous names on this forum are masters at this
But I actually believe designing stuff that 'sounds better' may help it to sell and make a profit. That's what I use DBLTs for.
Hi Petr,
You left out the Ayre amplifiers, designed by Charlie Hanson. His no-NFB amplifiers sound beautiful. Amplifiers sound different for many different reasons. Some people like single-ended triodes. To me, most of them sound awful. Its often a matter of personal preference. In fact, some people prefer the sound of amplifiers that are not strictly neutral. An amplifier with low damping factor, such as a typical tube amp or many no-NFB amps, will not be very neutral with many speaker loads whose impedance varies all over the map with frequency.
It is certainly not a "fact" that negative feedback is not conducive to proper sound reproduction. Virtually all of the pseudo-technical reasons that have been put forth suggesting that negative feedback is bad have been de-bunked. This does not mean that NFB is perfect. For example, sometimes NFB amplifiers overload or clip differently (and maybe not as nicely) than no-NFB amps. Some less-well-designed NFB amps can have stability problems and may burst into parasitic oscillations under some conditions of program material and loading. One can always find examples of poorly executed designs, be they with or without NFB.
Cheers,
Bob
Those aiming for lashings of zeroes after the point tend to only design their amplifier in isolation, rather than accepting its only a part of a larger system which includes a loudspeaker. Thus they get their impressive numbers only with a resistive (i,e, completely linear) load. If they were to attach a real-world (i.e. non-linear) load those zeroes quickly begin to evaporate because their output impedance isn't low enough. Even were they by herculean means to get sub-microhm Zout they'd then have to ensure sub micro-ohm connecting resistance between their baby and the transducer. This means no passive XO and no speaker cable can be permitted, severely restricting the choice of available speakers.
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Richard, there is NO listening panel on your side, when you work on your new project. And a lot of experiments you have to figure-out. The only thing you can use is *your* ears and your ability to discriminate.
The one of black matter in amplifier is about damping-timing or delayed interaction of speaker-amplifier. I still try to figure it out, it is hard to determine because of complec cause and various different types of results.
None of them in my best sounded amplifier list.
No feedback type is easier to reach more plesant sound, but harder to reach better sounded amp.
If your friend best amp is non feedback, he may like pleasant more than beauty.
I remember one of good configuration of CFA using ACCUPHASE P-700 Power Amp + Apogee Scintilla ribbon, the owner use them till end of his life.
You are right. And I like to believe I say similar things both when blind and when sighted about what I hear.
But when the project nears completion, I believe it is essential to involve others and myself in DBLTs. I was fortunate in being able to organise my own R&D Dept. around this.
My most successful design was best selling speaker in Europe for more than 7 yrs and once one of the 3 best small speakers in the world. It was a cheap design and looked it. I ALWAYS score it higher in Blind tests compared to when I can see it.
The best ears are just as opinionated & prejudiced as the deaf Golden Pinnae .. and I've had some of the very best on my Blind Listening Test panel. The difference is true golden pinnae turn in consistent results in DBLT.
A vital factor in my DBLTs is that you NEVER tell the listeners what they are listening to. Whether its 2 amps, phase, dither, A/Ds etc. They are just asked to listen to A, B & C and if they think they can tell a difference, to give a preference if any. I myself am not told.
There are evil rumours I sometimes make all 3 presentations the same but the test is too difficult & expensive for me to waste by doing that.
Up to now, it is an an unexisting matter.
The only time delay in a feedback loop is due to the travel of the current through a few cm at the velocity of 300000 km/s.
How could exist electrically servo-controlled damping in loudspeakers (by velocity like in Rythmik products or by negative resistance like in Stahl inspired Audio-Pro or Yamaha products) if there was any significant time delay in the negative feedback process ?
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Velocity of the sound propagation through the universe is not easy to measure.
listen or hear ? A huge difference.
Currently, my prefered sentence relative to audio is
Ca s'entend à l'écoute (It is heard when listening).
There are many more measurable phenomenons which can't be heard than there are non-measurable facts which are "listenable".
That should be ".. 2nd best selling speaker in Europe for more than 7 yrs .."
An illustration of wishful thinking which is also a huge factor in sighted listening tests
Ok, for interest, 2nd by what differential, and what were the makes and models of those first two...or three.
Regards, Dan.