Joe
Repeating the same things in front of adults is not that good.
Persistence is a bad thing when it is linked with an agenta in non commercial threads in this site
In your posts I fail to see any sign of technical progress. Please get into the trouble and provide appropriate links.
You don’t always succeed in hiding your real interests.
Consider rereading Rule #8 and Note #5
diyAudio Rules
George
From here Motional Feedback - Wikipedia "To a degree, the sensor-feedback system also compensates for non-optimal room acoustics". Does it??
If I understand what you mean then not sure wikipedia got it right, the feedback sensor is bascially an accelerometer mounted on the woofer to measure cone movement and deals with the magnet and voice coil interactions. Essentially non accoustic. I posted some stuff including a Philips paper about motional feedback a few pages back.
There is absolutely nothing new here. This is always how it has been.
Joe you have it in your grasp with this simple picture, get a good amplifier like one from Halcro (they're local?) and put one of your shunt networks across it and now measure the current in the VC.
EDIT - Guess not, metal detectors were more lucrative than audio, there are others. You could do a quick thought experiment assuming an ideal voltage amplifier at the input and explain how the current in R1 can be changed by any shunt circuits at the input.
Last edited:
I really do not get it, that someone doesn't understand that an ideal sine voltage source keeps the sine wave voltage output with zero distortion regardless load impedance and load variances. Load current is then voltage divided by load impedance and if impedance is nonlinear, current must be nonlinear. If someone doesn't understand this, then he doesn't know Ohm's law and should not participate in a discussion on such topic.
OK, this is escalating and that is a sign that I should just opt out and play a game that is time based.
To Paul (PMA), my thanks to your contribution and I should have given you more credit as I have posted some of your stuff.
But I just want to say that things have moved since 2015, but your work is very supportive, but I still don't think (and others are on board with this) that you have not fully seen the mechanism that explains the results you have shown (and thanks for your efforts) and that the methodology you used is taken to the next step.
This is going to take time, but I hope you will find the expected results convincing. Let the chips fall where they may. If successful, the result will add to what you have provided and will be a feather in your nest. You helped point the way.
Cheers, Joe
To Paul (PMA), my thanks to your contribution and I should have given you more credit as I have posted some of your stuff.
But I just want to say that things have moved since 2015, but your work is very supportive, but I still don't think (and others are on board with this) that you have not fully seen the mechanism that explains the results you have shown (and thanks for your efforts) and that the methodology you used is taken to the next step.
This is going to take time, but I hope you will find the expected results convincing. Let the chips fall where they may. If successful, the result will add to what you have provided and will be a feather in your nest. You helped point the way.
Cheers, Joe
Very good Scott, very perceptive. this is not far from what we are going to do, but I hope you don't mind that the details will not be prematurely published. This is what is being worked out right now. The electrical side is obvious, but the acoustic side, that maybe will have to be stage two. I do have the equipment here to make it possible. I have January in mind, but the results will go to 'insiders' first - like a little peer review, which I think you can appreciate. Nobody likes to look like an idiot, right? 😉
Re Halcro, yes I have met the present designer. I could indeed use one of his amps, but not strictly does not have to be his. It will be a voltage source, that is for sure. This is about getting the current of a voltage source right. Let us see if it can be done - so far all the indicators says it can be and is doable.
Oh dear, after midnight again. This ol' geezer needs some sleep.
Cheers, Joe
Actually, the motion of the coil is a result of the vc current, the mass of the coil and cone, the eddy dragging forces in the gap, the coupled air mass, the direction of the air mass movement, and the stiffness of the air mass in front of and behind the cone. In short, it's motion is a result of the sum of forces.
It is that summation of forces that the amp is seeing by the current drawn from the amp.
The output voltage is exactly the velocity it wants the coil to have. The output current is the force required to do so.
All energy stored in the load system is called reactance, and that energy is returned to the amp during operation in quadrants two and four. Also, that reactance is velocity , acceleration, and position dependent
All energy that does not return to the amp is converted to acoustic energy or heat energy.
Oh, forgot to mention..putting a one ohm resistor in series with the load changes the V/I characteristics. Better off with either a dcct or a ten milliohm resistor. But make sure the resistor does not produce a dB/dt component.
Jn
Last edited:
Demian,
I believe ALL encoders are cheaper than renishaws. Well, maybe not heidenheims.
I like the U/S technique. It seems analog, the renishaws are so digital. I wonder what resolution would be needed, I use 10 nanometer and 1 nano resolution units but don't know what the interpolated bandwidth is nor the 1 nano accuracy.
Jn
I believe ALL encoders are cheaper than renishaws. Well, maybe not heidenheims.
I like the U/S technique. It seems analog, the renishaws are so digital. I wonder what resolution would be needed, I use 10 nanometer and 1 nano resolution units but don't know what the interpolated bandwidth is nor the 1 nano accuracy.
Jn
... would be nice but would need clean amplification to get signal big enough to read distortion spectrum. And, 10 milliohm resistor should be carefully designed because of its intrinsic inductance, not trivial.
Sounds about right to me.
Getting past that is a problem as we all develop along conscious and unconscious norms. In youth we parrot as a way to speed learning and to extend our life/living/termination prospects. This was necessary in the origins of the animal or body aspect. Come up into the group (as a norm within it) fast, or die from the unexpected in the environment's complex harshness.
There is an area of thought in the sciences of intelligence that feels that intelligence itself is a temporary function that is not to be always on as this is metabolically taxing. Too much energy use. It can't be held or sustained. This is substantiated to a notable extent via a considerable body of work.
In such matters, the body utilizes rote repetition and conditioning, via observation of the world. That notable aspects of our so called conscious awareness are patterned things as response to input, and have little to no correlation to rumination.
These mental aspects weave in and out of one another, constantly, in and around every heartbeat and motion. Instinct, intellect, and emotions intertwined in a dance that few recognize as existing. A rather slick and well developed system. Conflation between these aspects is the breath to breath norm, not the exception.
It is pasted upon us so hard, it is relatively inescapable enough, regarding the idea of getting enough distance to see it. The ego will not allow, as it's job is to be the highest level programing subsystem barrier penetrating loop and function call/response system, to integrate such in the mental and biological.
Then the issue of people being in engineering as that other stuff makes them and their monkey......uncomfortable.
So they can't complete and define the questions well enough to reach a functional answer. And they go into looping (via the above aspects), with the incorrect question attempting to answer something that has no fundamental context. Some folks being so far off the correct path that they dismiss the complex aspects of the question as being vaporous and pouring out of the misled and the charlatans.
These are standard aspects that can be seen in all questions that tax human limits.
Essentially, if one wants to answer these problems in audio, the question set and definition of such....is in need of correct expansion. So the answer and question can be equal to one another in a way that answers the entire package. As in where people's perceptions are not fudged out as imaginings so that the engineer can get back to doing what they think they know.
Last edited:
At least have you guys thinking. The dB-SPL is off course related to all sorts of things, like Jn indicates. But some times you have you use thought logic like "if all things were equal, then..." or else we shall be buried in minutia. So in that conditional sense, the dB-SPL is still directly related to the current (which can be influenced by many things) in the voice coil. I struggled with that a bit too, so even if eddies exist, air load impedances, cone imperfections and resonances, poor cone edge impedance terminations and poor design basket reflections, oh boy, the list is endless... but then it just occurred to me what was obvious, and I played this idea before others, that this simply alters the back-EMF impedance (an impedance is the degree to which current is impeded, not voltage).
What is the back-EMF impedance? The impedance that measures above the Re value of the voice coil. Just pure logic, because they are in series.
The Re is stable, the back-EMF impedance is not. The Re has some thermal dependency, but the back-EMF impedance is highly malleable to all sorts of flaws and conditions. This alters the current of the voltage amplifier, the current is then presented to the driver and the result is that the current changes the dB-SPL. This is what Paul's measurements have demonstrated (and others too, but his example I do like). But now comes the final and most important point, the current being modified becomes a loop, the modified current is further modified and goes back to the amp, which reacts to and further modifies the current, and you got time smear and potentially something that roughly speaking becomes some kind of noise floor. The modified current continues to be modified as if stuck in a loop, a cat constantly chasing its own tail.
Think about it, try to understand the mechanism, maybe even find words to describe it better than I have.
OK, 2.16AM, goodnight.
High level complex stimulation of the complex motor.
Depends on the definition of the question.
A disassociated and non-linear set of reactive response to stimulus aspects, for one.
Last edited:
Yes. I had a paper somewhere... a guy doing a laser based cone sensing mechanism for a phd I think it was. Measured cone position at a lot of places very accurately. He was trying to design better cone / piston / drive arrangements, but had observed that it could provide distortion reducing feedback too.
This does not happen, and there are no words to describe it. Feedback does not go round and round it reaches a steady state. You keep stating that no amplifier can drive a load with nonzero phase without being "tricked" into having bad reactive current. This does not belong in a technical discussion.
You might very well run across bad amplifiers that oscillate with your cable/speaker combo, get rid of them.
Yes, sorry as well. I think I told in the past I was involved in design of these things.
Attachments
- Status
- Not open for further replies.