No, the inconvenient truth is the ignored non direct relation of acoustic output to F.
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Would you repeat that? You are saying that the two do not correlate? But they do!
You realise just how wrong that is, don't you? Have you seriously thought this trough?
Wow!!!
PS/Edit: Clue, change the current and measure the acoustic change in level (the dB-SDPL) and they 100% correlate !!!
Wow, show us the equation or measurement then. Talk is cheap. Do you realize that you are saying mass of moving parts, spyder, surround and cone breakup has negligible or no effect?
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This is truly amazing, something I have measured over and over again and you are saying this for real?
And you presume to lecture me?
Do it yourself:
Get any old driver, put a microphone in front of it. Now put a signal through it. Measure the current. Measure the dB-SPL of the driver. Change the current, double it. Now note that the dB-SPL of the driver has increased by.... 6dB!
YES!
I am sorry, I really do not mean to offend you, even if your are trying to offend me, but...
How much do you really know about speakers? Hands-on experience?
Note: It is the change in current that prove F = BLi is 100% true every time. This means mass, suspension and cone breakup and anything else you can think of, is not an issue. You are looking at the wrong thing.
Talk about looking at the trees and not seeing the forest. Please do not presume to lecture me after this.
A speaker is an inanimate object and has no concept of control. This isn't an argument about descriptors, but an argument about the purposes we have for assigning those descriptors. Jneutron and ETM disagree on the descriptor but not the operation of the speaker. If you compare the reasonable arguments for the descriptors, they differ in the purpose the descriptor is given for, not the way a speaker operates.
F=bli is part of the answer but the relationship between F and SPL changes with frequency, not to mention the nonlinearities in all the links between current in and cone motion. At higher frequencies the delay between voltage or current in and sound out becomes significant and all manner of issues surface in that delay. And then current in is not always proportional the sound out. At low frequencies you can get compression at higher levels. At low levels the internal stiffness and friction in the suspension can reduce or eliminate output.
Re phase, look at tone bursts and the relationship between the electrical in (both voltage and current) and the acoustic out. You would think an electrostatic would have a different output with peak displacement from voltage rather than force from peak current.
Re phase, look at tone bursts and the relationship between the electrical in (both voltage and current) and the acoustic out. You would think an electrostatic would have a different output with peak displacement from voltage rather than force from peak current.
And all speaker manufacturers throw all that good money to the dustbin on research of cone, spyder and surround. Such a waste.
Seriously Joe, I wish the world is as rosy as you paint, makes my life way simpler.
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And all speaker manufacturers throw all that good money to the dustbin on research of cone, spyder and surround. Such a waste.
Seriously Joe, I wish the world is as rosy as you paint, makes my life way simpler.
So a measurement I have done hundreds of times is false? This is FACT you are rejecting.
Let me put it to you again, I even told how to test it, any change of current in the coil of a linear motor (speaker) gives an exact same change in the SPL of the driver. What is there not to explain?
The key word here ins change and if that logic is not understood, I am not wrong, but I am truly amazed at something this simple is being thrown out.
No, what gave you the idea that my life was to make life easier for anybody?
Again, very odd comeback. I don't care for the price of tea in China either.
Do the test!
It is the answer, but not the way you express it.. partly?
Are you confusing losses? Of course F changes with frequency, but that is shifting the goalposts. We all know that.
The proof is that a change in current causes a corresponding change if the SPL of the driver at the same frequency. That is all you have to do to prove F=BLi as correct.
Yes, it is. I posted results earlier that proves this. Please go back and rethink what you are saying. You are bringing things that do not change the result. You change the current at any frequency, check before and after, and you will see this never fails.
The reason I am so emphatic is that I have done this and can physically prove to anybody who is willing to come through my door. Words saying that is not true is cheap.
Besides, this is a test that you can do too. Then just do it - nature will take care of itself. Trust me, please.
Not to Richard apparently as he hasn't attempted to answer it, I didn't expect him to, he trades in ambiguous descriptors.
That argument is not valid. Clearly, we are talking about like for like. So of course the F changes with frequency because the current changes with frequency. Consequently F=BLi still works the same at that new frequency as it did the old frequency. The rule does not change just because you changed frequency. Surely you must be able to see that?
I have done this test, and it works at any frequency! Just make the two necessary measurements at that frequency and you have all the proof you need.
You can do it too. Pick a frequency. Change the current. Change the change is SPL. It will never fail. The change or ratio will always be the same.
I have done this - I am not lying.
I would think this has been answered several times in the past. Reduced influence of the Le(x) characterstic being a main component, significantly seen with VC-based cone/dome drivers with simpler, less symmetric motor structures.
As for the circuit, here's one of the early references to implement a partly current-derived feedback to increase output impedance.
With all due respect Joe, I have no intention to offend anybody. I think almost nobody here ignores the implication of F=BLI, that also includes the inconvenient effects of frequency and other mechanical issues.
I do think that your solution has some good merits but the way of the explanation does not connect with so many here. The bunch who post in this thread are those interested in "John Curl" and "Blowtorch Preamplifier". There is little hope for you to effectively communicate with us here if you are not willing to acknowledge common electrical laws and terminology we use to make a living. We simply can not ignore any inconsistency on pain of fatal failures of our circuits.
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That is because I am Asking the question. I expect you or someone to give the answer. I mean, it is a simple circuit config. Only one part.
Where is all this EE brain power here that JN waxed poetically about?
THx-RNMarsh
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I think he may have gone to a higher impedance out and my guess is 18 Ohm.
I was at ETF17 (European Triode Festival 2017) and Menno Vanderveen had us listen to a Class D amplifier with switchable output impedance in a room of people. It was zero, 3 Ohm and 18 Ohm o/put Z.
Menno actually preferred the 18 Ohm switch position. So that makes me wonder...?
Afterwards I asked him "is this was one of Bruno's amplifiers" and he said it was.
The following year ETF18 there were more discussions between Menno and myself plus others. I showed Menno where I was up to and there is a genuine interest to keep this subject of 'current' going. The subject is hotting up. I also found out that Menno says to his class "voltage is easy, current is hard." He certainly is right there. People heads starts swimming, but as you explain it, they do come around.
Note that in Melbourne Marc Rushton of SGR Audio, his active speakers now also incorporate current drive. Three models I believe.
The whole subject of better understanding current in loudspeakers is now really hotting up. It isn't just about current drive versus voltage drive. That is would be missing the whole point.
But current drive does lend it to closed systems, active loudspeakers. They use it mainly on mids and tweeters, but not on bass. But I have solved the LF problem and my speakers be current driven.
You have shown a circuit with current sense being fed back. And volt fb also. Different ports. I am not sure this circuit does the same thing..... reduces THD from the driver. Reduces the transformer THD though. My question is still unanswered.... HOW does it reduce distortion from the speaker in My circuit.
THx- RNMarsh
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See "mixed mode feedback" Fig 2 Variable Amplifier Impedance
Joe's talking about a zobel network across the speaker terminals
Basically is seems there are people here wanting money for old rope
Joe's talking about a zobel network across the speaker terminals
Basically is seems there are people here wanting money for old rope
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