Classic misdirection - by YOU!
Can you address the substance, please?
Don't you believe what you see on an oscilloscope? Or you don't know how an oscilloscope works? (I don't know you, so how would I know?) You have two channels, usually labeled CH1 and CH2. Using a current sense resistor in the return leg of the driver, something low as 0.1 Ohm would be good, but Pavel used 1 Ohm and it still worked. So you put the voltage of the amplifier on CH1 and you put the current on CH2. Can you now see two separate sinewaves on the scope? Where did they come from? Why, the same amplifier. Hear that sound coming out of the speaker? It has to come from somewhere.
So, the two sines are different, they don't line up in time (30 degrees out), so we must be listening to one or the other?
It is a question? No misdirection, no obfuscation, no little dirty trick and no secrets, just a question.
Will you address the substance now?
If you need a hint, it is not CH1.
Ok, no, it's not the case that we are listening to one or the other. Simple answer to a simple question, is that ok with you?
When dealing with complex electronic relationships such as voltage, current, and phase I feel like things are not so cut and dry as to simply refer to it as two separate sinewaves, and I'm not so sure it's the easiest to try to look at them as two traces on a screen. Perhaps a 3D waterfall type of graph would be easier to see things in situ better? Maybe this will show the rate of change of the current as a consequence of the change of voltage?
Keep in mind I'm not well versed on advanced measurement techniques and equipment, but phase and inductive reactance always felt like a bit harder to articulate with something like an oscilloscope when it comes to a dynamic load like a speaker, since there are multiple things going on that a simple inductor doesnt feature, such as back EMF from the mass of the cone resisting movement to an extent, lag from physical factors and loading, etc.
If I don't seem to grasp it well I would love some recommendations on reading that isn't terribly math heavy but is a bit more practical.
Keep in mind I'm not well versed on advanced measurement techniques and equipment, but phase and inductive reactance always felt like a bit harder to articulate with something like an oscilloscope when it comes to a dynamic load like a speaker, since there are multiple things going on that a simple inductor doesnt feature, such as back EMF from the mass of the cone resisting movement to an extent, lag from physical factors and loading, etc.
If I don't seem to grasp it well I would love some recommendations on reading that isn't terribly math heavy but is a bit more practical.
Then you have missed the point. Here is an EE, like many, who doesn't know how to measure current distortion. But at least he acknowledges its existence, unlike many EEs!
That quoted post is also nonsense based on a fundamental misunderstanding of the basics.
I've no idea. He is in the audio business so the post may have just been spurious nonsense for other reasons.
So if the current sinewave has a different distortion than the voltage one - and you use a current feedback amplifier (one that obtains the current waveform in the same way it's measured with the scope) doesnt that reduce the distortion by forcing the voltage to whatever it takes to make the current follow the input?
So if the current is what you hear from a speaker, just use -
- a current feedback amplifier (hi-Z out)
- a voltage / current mixed feedback amplifier (fixed Z out)
- an amplifier with a "natural" intrinsic current feedback mechanism (current drops a voltage across OPT windings resistance / impedance)
Or flip that, if these types of amplifiers simply sound better (than the ones where output current can be anything and they just dont care; 0.001 Ohm Z out) for "some mysterious reason", perhaps their making the output current more true to the input voltage signal has something to do with it. Therefore what you're hearing is...
So if the current is what you hear from a speaker, just use -
- a current feedback amplifier (hi-Z out)
- a voltage / current mixed feedback amplifier (fixed Z out)
- an amplifier with a "natural" intrinsic current feedback mechanism (current drops a voltage across OPT windings resistance / impedance)
Or flip that, if these types of amplifiers simply sound better (than the ones where output current can be anything and they just dont care; 0.001 Ohm Z out) for "some mysterious reason", perhaps their making the output current more true to the input voltage signal has something to do with it. Therefore what you're hearing is...
I dunno, I like idealized solutions.
The fact that current moves the driver is inescapable.
Maybe my thinking is too simple on this but I feel it would be best to design drivers to function well on current drive rather than trying to work around it and making stuff convoluted.
Perhaps dynamic drivers just can't cut it, that's why I like alternative technologies, they sound better anyway.
The fact that current moves the driver is inescapable.
Maybe my thinking is too simple on this but I feel it would be best to design drivers to function well on current drive rather than trying to work around it and making stuff convoluted.
Perhaps dynamic drivers just can't cut it, that's why I like alternative technologies, they sound better anyway.
To me that sounds perfectly normal & natural for a linear motor.
There will be a phase lag between current and voltage, just look at the kind of behaviour of any motor used to drive a train or a tram.
I simply can't understand why this should be regarded as anything either bizarre or weird.
Please would you like to explain why an audio "motor" should be any different??
It has exactly the same asyncronous and syncronous problems with mass and accelereration as any ordinary industrial motor inc shaker tables (one thing my amps were actually designed to drive!).
That's what I was wondering.
Also I posted the schems from earlier here for people to discuss if they want.
50W super triodes and stuff
Surely something in there can be used to isolate "tube sound" if it exists. The only one I haven't tried is the super triode schem which is probably the most likely to be able to do so considering the ability to let the tube react to the load and control the output without worrying about the current required to drive the load.
Also I posted the schems from earlier here for people to discuss if they want.
50W super triodes and stuff
Surely something in there can be used to isolate "tube sound" if it exists. The only one I haven't tried is the super triode schem which is probably the most likely to be able to do so considering the ability to let the tube react to the load and control the output without worrying about the current required to drive the load.
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If I take a photo of myself from the front and another from the back, can I conclude that I'm two people?
Then take a look at the load, the third and final part of the puzzle. It's one thing to analyse current and voltage individually, and another thing entirely to conclude that they are separate things.
the separation between voltage and currents appear only in analysis and calculations, in the real world, if we are to make something out of them, then there is real time "power"...
the power input to any speakers is what moves the cones that in turn move the air that produced the sounds that we hear....
to say current only, or voltage only is the height of folly...
the closest that i come to understanding the issue is the level of output impedance of amplifiers, it could be very low, << 1 ohm for what is claimed as voltage sources or high as in 1>> for current sources, and i can live with this, there must be a delineation somewhere as this is the only way to understand...
this is not a black and white thing, i believe that there are overlapping shades of grey areas...
to insist that this is a black and white thing will be stupid, and the thread has been tolerated for the simple reason that this board had no rules against stupid...
i have insisted on drawings/schematic of amps as that is a sure way to understand, but instead people can only blah blah blah...
and sank this thread to a Lounge material....
AllenB, congrats on your mod hat, unsolicited advice, try not to over moderate, just have fun and roll with the waves, good luck, good man yourself....
the power input to any speakers is what moves the cones that in turn move the air that produced the sounds that we hear....
to say current only, or voltage only is the height of folly...
the closest that i come to understanding the issue is the level of output impedance of amplifiers, it could be very low, << 1 ohm for what is claimed as voltage sources or high as in 1>> for current sources, and i can live with this, there must be a delineation somewhere as this is the only way to understand...
this is not a black and white thing, i believe that there are overlapping shades of grey areas...
to insist that this is a black and white thing will be stupid, and the thread has been tolerated for the simple reason that this board had no rules against stupid...
i have insisted on drawings/schematic of amps as that is a sure way to understand, but instead people can only blah blah blah...
and sank this thread to a Lounge material....
AllenB, congrats on your mod hat, unsolicited advice, try not to over moderate, just have fun and roll with the waves, good luck, good man yourself....
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To me that sounds perfectly normal & natural for a linear motor.
There will be a phase lag between current and voltage, just look at the kind of behaviour of any motor used to drive a train or a tram.
I simply can't understand why this should be regarded as anything either bizarre or weird.
Please would you like to explain why an audio "motor" should be any different??
It has exactly the same asyncronous and syncronous problems with mass and accelereration as any ordinary industrial motor inc shaker tables (one thing my amps were actually designed to drive!).
people with no engineering education will never understand, although they can if they do due diligence and study with an open mind....
ac analysis started and expanded by Charles Steinmetz are well know at the start of the 1900's.....Charles Proteus Steinmetz - Wikipedia
it would help if you explain and justify your drawings?
btw, i thought that the russian 6H30 were super triodes? that's the first attribute i ever saw given to a triode, and now another russian the 4P1L too?
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I don’t think anyone is saying that. At on end of the spectrum we have fixed volatge rails and deliver variable power with near zero source impedance, while at the other end it is a fixed current rail and volatge is varied with source impedance near infinity. When you take those and add the elecrical analogy of the speaker the math comes out quite different (all shown in great detail in ESA’s book).
I am trying to get my head around the 2 curves. They come from the same place, the phase shift shows a reactance in the speaker, and what i think is more important is the distortion that shows up when you measure the current that is not in the volatge. It would be nice to see the residuals on those measures,
What happens when you use s sin frequency that falls into a near pure resistance place on the curve? In theory the phase shift should go away.
dave
but that is the impression one gets from the posts.....
what incontrovertible truth is that voltage x current is power...
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