Joe, you said above: “this idea that there is some kind of brake going on is something I greatly disagree upon”
Another quote from the Newell and Holland book:
This electrical damping effect can be easily tested by lightly tapping the cone of a low frequency loudspeaker with the amplifier connected but turned off, then comparing the sound by tapping again with the amplifier switched on. A significantly deader sound should be heard in the latter case, when the near zero output impedance of the amplifier short circuits the voice coil.
I tried this and I definitely heard what is described in the above paragraph. The thump was much tighter with the amp on, boomier with the amp off (actually, I disconnected the speaker wires). Isn’t that the brake idea you disagree with? Does having a constant voltage on the voice coil restrict movement somehow? Maybe this test isn’t testing what it is claimed to test?
Another quote from the Newell and Holland book:
This electrical damping effect can be easily tested by lightly tapping the cone of a low frequency loudspeaker with the amplifier connected but turned off, then comparing the sound by tapping again with the amplifier switched on. A significantly deader sound should be heard in the latter case, when the near zero output impedance of the amplifier short circuits the voice coil.
I tried this and I definitely heard what is described in the above paragraph. The thump was much tighter with the amp on, boomier with the amp off (actually, I disconnected the speaker wires). Isn’t that the brake idea you disagree with? Does having a constant voltage on the voice coil restrict movement somehow? Maybe this test isn’t testing what it is claimed to test?
For some reason I don't get the quote option of the last post. It has to become the second last post before I do. I only get the Report and Like options.
Is there a setting I need to change?
OK, here we go and this is a good one.
Re Newell and Holland, I have seen that argument many times in the past. It gets recycled over and over again. I admit it, it's a beauty, but it is also a pitfall.
Again this is about misinterpreting the result. There is no electrical damping when the voice coil Re is infinite. This is very deceptive argument, but the conclusion is wrong.
This above, is the Thiele-Small equation for the electrical damping Qes, which is in parallel with the mechanical damping Qms.
Note the Re part of the equation? I have intentionally highlighted that in red. What you feel when the driver is connected to the amplifier, assuming the amplifier is a voltage source (99.999% sure) and the output impedance is near zero, then it is exactly the same if we were to short the driver terminals. You have shortened the voice coil. The Re in the equation is the the DC resistance of the voice coil inside the driver. But any additional impedance or resistance, like cables and inductors, these modify the Re and often by a lot.
Looking at that equation, can you now see it?
If the Re was made infinite, the Qes would also be made infinite. Ergo, no electrical damping at all. The test is flawed because you haven't connected the driver to anything.
Indeed any percentage change in Re would make the same percentage change in the Qes. Add any output impedance and the Re goes up10%, then the Qes will erode and go up the same 10%. If the Qes had been 0.3, now it becomes 0.33 and so on. Until you make Re infinite, then Qes would be infinitely high too. And you would no electrical damping because you have an open circuit.
So do the same experiment without an amplifier, just get some alligator leads and shorten the terminals. You get exactly the same effect. No need for an amplifier.
Is anybody going to suggest that an alligator lead is acting in some intelligent way as a brake?
Of course, the question is ridiculous, yet that is what is being suggested.
It is only a bit of wire.
So really nothing has been proven except that you have made the voice coil wire inside the speaker doing absolutely nothing when it is open circuit. Just a string of copper wire curled up. It won't do anything.
Also, electrical damping is not the same as the brake that is being suggested here. Damping effectively causes a kind of friction, so that is what you are feeling when the voice coil is in circuit and, it does not matter what it is that completes the circuit. The idea that the driver over-shoots and then generates a current that flows back into the amplifier and applies some kind of brake and pulls the cone back in line, that simply does not occur, sorry.
Before anybody suggest that the above is somehow snake oil, may I quote Esa Merilainen in his "Current Driving of Loudspeakers" on page 29 says:
"To the same pseudo-scientific wishful thinking..., also belong the fiction that an output impedance as low as possible... 'controls' the speaker and hence as though prevents extraneous oscillations [overshoots]."
Esa goes on to explain further re the bac-EMF that is supposed to be generated is overcome by the fact:
"[That] motion is due to the drive force [only] is directly proportional to the current."
[] added. Because there are no exceptions.
The position of the cone is always decided by the current. If the cone ends up in the wrong place, it is because the current has been corrupted and then you have other problems. It cannot be corrected in the way that is being suggested. The overshoot simply does not happen the way that popular notion thinks. The back-EMF does not correct anything at all, rather it can mess up the current and then create an error signal that cannot be used as a correction mechanism.
An extremely bad bass driver will sometimes start doubling by producing bad distortion by outputting double the frequency. I have tested bass drivers and some when pushed starts to make noises. Good drivers does not do this. But even if a driver does this, it is not overshooting and there is no way anything can be done to correct bad driver design, like a bad suspension etc.
I have tried to keep it simple as possible. But the fact is that really knowledgeable people are around and they fully know this the truth about this wife's tale.
Except it can be undone with a single pair of alligator leads. 😳
And it can be disproved in other ways too, with microphone and current meter.
Cheers, Joe
Is there a setting I need to change?
OK, here we go and this is a good one.
Re Newell and Holland, I have seen that argument many times in the past. It gets recycled over and over again. I admit it, it's a beauty, but it is also a pitfall.
Again this is about misinterpreting the result. There is no electrical damping when the voice coil Re is infinite. This is very deceptive argument, but the conclusion is wrong.
This above, is the Thiele-Small equation for the electrical damping Qes, which is in parallel with the mechanical damping Qms.
Note the Re part of the equation? I have intentionally highlighted that in red. What you feel when the driver is connected to the amplifier, assuming the amplifier is a voltage source (99.999% sure) and the output impedance is near zero, then it is exactly the same if we were to short the driver terminals. You have shortened the voice coil. The Re in the equation is the the DC resistance of the voice coil inside the driver. But any additional impedance or resistance, like cables and inductors, these modify the Re and often by a lot.
Looking at that equation, can you now see it?
If the Re was made infinite, the Qes would also be made infinite. Ergo, no electrical damping at all. The test is flawed because you haven't connected the driver to anything.
Indeed any percentage change in Re would make the same percentage change in the Qes. Add any output impedance and the Re goes up10%, then the Qes will erode and go up the same 10%. If the Qes had been 0.3, now it becomes 0.33 and so on. Until you make Re infinite, then Qes would be infinitely high too. And you would no electrical damping because you have an open circuit.
So do the same experiment without an amplifier, just get some alligator leads and shorten the terminals. You get exactly the same effect. No need for an amplifier.
Is anybody going to suggest that an alligator lead is acting in some intelligent way as a brake?
Of course, the question is ridiculous, yet that is what is being suggested.
It is only a bit of wire.
So really nothing has been proven except that you have made the voice coil wire inside the speaker doing absolutely nothing when it is open circuit. Just a string of copper wire curled up. It won't do anything.
Also, electrical damping is not the same as the brake that is being suggested here. Damping effectively causes a kind of friction, so that is what you are feeling when the voice coil is in circuit and, it does not matter what it is that completes the circuit. The idea that the driver over-shoots and then generates a current that flows back into the amplifier and applies some kind of brake and pulls the cone back in line, that simply does not occur, sorry.
Before anybody suggest that the above is somehow snake oil, may I quote Esa Merilainen in his "Current Driving of Loudspeakers" on page 29 says:
"To the same pseudo-scientific wishful thinking..., also belong the fiction that an output impedance as low as possible... 'controls' the speaker and hence as though prevents extraneous oscillations [overshoots]."
Esa goes on to explain further re the bac-EMF that is supposed to be generated is overcome by the fact:
"[That] motion is due to the drive force [only] is directly proportional to the current."
[] added. Because there are no exceptions.
The position of the cone is always decided by the current. If the cone ends up in the wrong place, it is because the current has been corrupted and then you have other problems. It cannot be corrected in the way that is being suggested. The overshoot simply does not happen the way that popular notion thinks. The back-EMF does not correct anything at all, rather it can mess up the current and then create an error signal that cannot be used as a correction mechanism.
An extremely bad bass driver will sometimes start doubling by producing bad distortion by outputting double the frequency. I have tested bass drivers and some when pushed starts to make noises. Good drivers does not do this. But even if a driver does this, it is not overshooting and there is no way anything can be done to correct bad driver design, like a bad suspension etc.
I have tried to keep it simple as possible. But the fact is that really knowledgeable people are around and they fully know this the truth about this wife's tale.
Except it can be undone with a single pair of alligator leads. 😳
And it can be disproved in other ways too, with microphone and current meter.
Cheers, Joe
Here the quote function was there and worked. There must be a setting somewhere...?
OK. It's the last question that is difficult and I don't want to go into a long answer again.
Basically the lack of electrical damping is caused by the amplifier providing constant current versus frequency.
You will note that I have used this expression a number of times and it is such a loaded phrase because it is at the very heart of understanding the difference between current drive and voltage drive. And it is not easy on the brain cells.
For example, if I was to pick any frequency under 100 Hertz and look at the cone and see a fair bit of excursions, but well within the limits of the driver.
Lets say I pick on 43 Hertz, but it could be any frequency.
Now let us connect it to a voltage source and measure the current (not the voltage). Now set up a microphone at 1 Metre and measure the sound pressure level in db, also known as dB-SPL. Let us say we measure 84 dB-SPL and that our current meter says 300mA.
Now swap the amplifier and use s current source amplifier with very high source impedance. Now adjust the amplifier so that 300mA @ 40 Hertz. Let's now look at our mic measurement and what do you think we will get? Surely with a current source it must be higher that 84 dB-SPL? Nope, it is exactly the same. And there is no overshoot because the whole operation is according to current and not voltage.
What if we increase the current to 600mA and look at our mic measurement? Now we see 90 dB-SPL. And it does not matter whether it is a voltage source or a current source, you will get the same result, plus 6dB when you double the current. The driver will not deviate from the current, irrespective of the amplifier used.
Current drive only gives us an impression that there is less damping. Even I had trouble understanding this and yes, I had some help here.
But there is a rub, the above test only works...
As long as we stick to a single frequency!
Vary the frequency and we get current changes with a voltage source and the frequency response looks good. But with a current source, the current does not change with frequency. Analyse that, think it over and over again. And when you have done that sufficiently, then think it over again. Why? Because when you are talking current it is really, really, hard!
Quote from Menno Vanderveen:
"Thinking voltage is easy, thinking current is hard."
[ETF19, where we were both attending.]
Enough typing today... whew!
Cheers, Joe
Thanks, Joe. You’ve given me a lot to think about. I don’t feel I have enough background to think about it coherently, but I’ll do some reading and, hopefully, thinking.
Intuitively, I understand that a moving coil in a magnetic flux induces a current in the wire, and exerts a physical force on it. So it makes sense to me that the alligator clip is doing something significant by allowing that current to flow, either collapsing or creating a field, I’m not clear, but something significant must be happening compared to not having the alligator clip. No?
Intuitively, I understand that a moving coil in a magnetic flux induces a current in the wire, and exerts a physical force on it. So it makes sense to me that the alligator clip is doing something significant by allowing that current to flow, either collapsing or creating a field, I’m not clear, but something significant must be happening compared to not having the alligator clip. No?
Hi Alan
Again I am missing the Quote option, and it is always the last post that doesn't have it. I am hoping a Moderator can help me out with it, so annoying.
Trust me, this topic is not an easy one and there are common inaccuracies out there.
Quote< Intuitively, I understand that a moving coil in a magnetic flux induces a current in the wire, and exerts a physical force on it...
Yes, but keep in mind that all of the heat it generates has to be dissipated by the driver's own voice coil, the Re we talked about earlier, which for a typical 8 Ohm driver is usually around 6R.
And if any current was to flow back through that alligator wire, is revealing as we look even closer at it. Tapping or pushing on the cone, then a small voltage will be generated, so the speaker becomes a voltage source. No current is going into the driver's voice coil without any load like an alligator lead.
The energy is coming from your hand! Not the driver itself! The voltage source in the driver, this converts your mechanical energy into a voltage. Now if we put a load on that voltage source, any current has to go through the 6R first. With alligator lead the entire 6R is shortened, the load is a short!
Heat is dissipated in the voice coil and no heat in the alligator lead. The resistance here is so low, the wire does not heat it up.
What if we don't use the alligator lead? What about an amplifier, what happens then?
Our voltage source amplifier's terminals and let's say the output impedance is 0.1 Ohm. Here the traditional thinking is that we have a damping of 80 because the nominal impedance is 8 Ohm and the output impedance is 0.1 Ohm and do the division = 80.
Does that mean our near perfect alligator lead has given a damping factor of infinity? Of course not. A wire can't add damping, then how can an amplifier?
Something is not adding up.
Back to the amplifier...
Now we will get a similar resistance on the cone compared to the alligator lead. It will seem to be the same. Here the analysis is a different one. The amplifier is silent. The amplifier is set to zero Volt. Our pushing on the cone might produce a peak voltage of 1 Volt. With the amplifier connected, the peak current would be 1/6.1 = 16.4mA peak current. The current has to go through the Re first and then it comes to the output of the amplifier. Here almost nothing happens as the amplifier is doing it job and presenting a zero Volt from shifting there. In our example the deviation would be 1.6mV and if the amplifier had a perfect zero output impedance, the no voltage would appear there, no matter how hard you would push the cone.
So you are right, current does flow, but just as the alligator lead having an ideal zero impedance, no voltage would appear across it and there is nothing you can do. There will be no heat expended in the shortening lead. It will all be expended by the Re voice coil resistance.
The same applies to the amplifier if it has a zero output impedance.
Do you see the point?
There is nothing for the amplifier to dissipate any current and absorb and dampen. No energy is being absorbed by the amplifier.
Indeed all the damping is occurring within the driver itself.
By the time the current gets to the output terminals of the amplifier, the job is done, inside the driver itself. That is the only place where any energy is being created and dissipated. Not in the amplifier.
I am going to make a statement that has gotten me into trouble in the past:
The amplifier cannot add damping.
The damping within the driver is at a maximum when it's terminals are shortened. The best an amplifier can do is have zero otput impedance and hence not make damping worse. Yes, that's right, since there are no amplifiers with a zero output impedance, then the inperfect amplifier can only make damping worse and never better. The Thiele-Small equation I posted yesterday, that indicates that the only way to increase damping is to reduce Re and the amplifier cannot do that. Only if the amplifier has a negative output impedance. And yes, negative impedance amplifiers have been done (added complexity of course), but that is another topic.
There is also another way that achieves the same thing, that 'trick' does not require any negative impedance. This is what is done in my Elsinore loudspeaker design, it is done through equalising the current. This cancels the output impedance almost down to 20 Hertz. The reason that current EQ works is that in reality, the speaker never requires damping from the amplifier. I know, a dangerous thing to say. But it is not snake oil. It has a better name... physics!
Cheers, Joe
Again I am missing the Quote option, and it is always the last post that doesn't have it. I am hoping a Moderator can help me out with it, so annoying.
Trust me, this topic is not an easy one and there are common inaccuracies out there.
Quote< Intuitively, I understand that a moving coil in a magnetic flux induces a current in the wire, and exerts a physical force on it...
Yes, but keep in mind that all of the heat it generates has to be dissipated by the driver's own voice coil, the Re we talked about earlier, which for a typical 8 Ohm driver is usually around 6R.
And if any current was to flow back through that alligator wire, is revealing as we look even closer at it. Tapping or pushing on the cone, then a small voltage will be generated, so the speaker becomes a voltage source. No current is going into the driver's voice coil without any load like an alligator lead.
The energy is coming from your hand! Not the driver itself! The voltage source in the driver, this converts your mechanical energy into a voltage. Now if we put a load on that voltage source, any current has to go through the 6R first. With alligator lead the entire 6R is shortened, the load is a short!
Heat is dissipated in the voice coil and no heat in the alligator lead. The resistance here is so low, the wire does not heat it up.
What if we don't use the alligator lead? What about an amplifier, what happens then?
Our voltage source amplifier's terminals and let's say the output impedance is 0.1 Ohm. Here the traditional thinking is that we have a damping of 80 because the nominal impedance is 8 Ohm and the output impedance is 0.1 Ohm and do the division = 80.
Does that mean our near perfect alligator lead has given a damping factor of infinity? Of course not. A wire can't add damping, then how can an amplifier?
Something is not adding up.
Back to the amplifier...
Now we will get a similar resistance on the cone compared to the alligator lead. It will seem to be the same. Here the analysis is a different one. The amplifier is silent. The amplifier is set to zero Volt. Our pushing on the cone might produce a peak voltage of 1 Volt. With the amplifier connected, the peak current would be 1/6.1 = 16.4mA peak current. The current has to go through the Re first and then it comes to the output of the amplifier. Here almost nothing happens as the amplifier is doing it job and presenting a zero Volt from shifting there. In our example the deviation would be 1.6mV and if the amplifier had a perfect zero output impedance, the no voltage would appear there, no matter how hard you would push the cone.
So you are right, current does flow, but just as the alligator lead having an ideal zero impedance, no voltage would appear across it and there is nothing you can do. There will be no heat expended in the shortening lead. It will all be expended by the Re voice coil resistance.
The same applies to the amplifier if it has a zero output impedance.
Do you see the point?
There is nothing for the amplifier to dissipate any current and absorb and dampen. No energy is being absorbed by the amplifier.
Indeed all the damping is occurring within the driver itself.
By the time the current gets to the output terminals of the amplifier, the job is done, inside the driver itself. That is the only place where any energy is being created and dissipated. Not in the amplifier.
I am going to make a statement that has gotten me into trouble in the past:
The amplifier cannot add damping.
The damping within the driver is at a maximum when it's terminals are shortened. The best an amplifier can do is have zero otput impedance and hence not make damping worse. Yes, that's right, since there are no amplifiers with a zero output impedance, then the inperfect amplifier can only make damping worse and never better. The Thiele-Small equation I posted yesterday, that indicates that the only way to increase damping is to reduce Re and the amplifier cannot do that. Only if the amplifier has a negative output impedance. And yes, negative impedance amplifiers have been done (added complexity of course), but that is another topic.
There is also another way that achieves the same thing, that 'trick' does not require any negative impedance. This is what is done in my Elsinore loudspeaker design, it is done through equalising the current. This cancels the output impedance almost down to 20 Hertz. The reason that current EQ works is that in reality, the speaker never requires damping from the amplifier. I know, a dangerous thing to say. But it is not snake oil. It has a better name... physics!
Cheers, Joe
You can manually quote something with the quote option.
Keep it up with your posts. They have been pretty interesting. I need to go back through them and read them again just to absorb it all 🙂
Hi Allan, look close below as a screen capture shows the problem.
OK, look closely below, how the second last post has the Quote option and that works.
But the last post, it is simply missing.
So Alan, since yours is the last post, I only get the
and not
.
If somebody then posts next, yours will magically become OK because you are not the last post. But the one after, which now becomes the last post, that post is now the one with the Quote missing. Really weird.
OK, look closely below, how the second last post has the Quote option and that works.
But the last post, it is simply missing.
So Alan, since yours is the last post, I only get the
If somebody then posts next, yours will magically become OK because you are not the last post. But the one after, which now becomes the last post, that post is now the one with the Quote missing. Really weird.
That is the way it is meant it to be. There is a discussion of the feature in the Forum Problems subforum.
Does this image demonstrate the control which you still have over quoting.. selecting text by dragging while holding your mouse button?
Does this image demonstrate the control which you still have over quoting.. selecting text by dragging while holding your mouse button?
I see. Thanks. At least I now know that it was not unique to my setup.
May take on it? Do we live in a nanny state? I know that I use the Quote function and edit it to suit my reply.
Edit: OK, I tried your suggestion and it worked for me. So I shall be neutral in all this. 😎
May take on it? Do we live in a nanny state? I know that I use the Quote function and edit it to suit my reply.
Edit: OK, I tried your suggestion and it worked for me. So I shall be neutral in all this. 😎
Joe, current in the voice coil makes force that moves the assembly, you know this, basis for the whole subject. Also electrical damping needs to be current in the voice coil in order to make the opposing force, electrical damping is opposing current, right. Its Lenz's law, physics, present in all electric motors and generators, no free energy.
Amplifier or alligator clip do not add damping or remove it, they just complete the electrical circuit so that current can flow in the circuit. Impedance of the circuit determines how much current flows for given voltage. Driver makes its own damping current into the circuit with its back-EMF voltage.
Impedance of this circuit, including voice coil, amplifier output impedance, any passive network, wiring, that are part of the circuit affect what the impedance on the circuit is and how much current the driver back-EMF voltage makes into the circuit, which makes damping force in the voice coil. This is the damping at driver resonance and distortion current above the resonance, current generated by driver back-EMF, current that opposes movement of the voice coil in magnetic field.
Driver damping, movement opposing force, opposing current, does not happen if the electrical circuit is not complete, current cannot flow. If impedance on the circuit is high only very small current flows, like with high output impedance amplifier, unless there is low impedance path around it.
Your current EQ is a shunt network that provides low impedance path in the circuit at the driver resonance frequency, which allows driver damping current to flow. A valid approach with high output impedance amplifier, driver dampens itself but no distortion current can flow at higher frequencies where impedance is high, best of both worlds.
If you ignore back-EMF and fail to analyze the circuit from drivers perspective to analyze load of driver to see damping (and distortion) current from back-EMF the explanations get very confusing and complicated, when its rather simple to analyze and understand like so.
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I am not sure why I was given a lecture on things I already know.
So I don't know about Lenz's Law? What? What did I say that makes you think that I don't. I think that every point by point I was observant of Lenz's Law. This is basic stuff. In fact I explained that the effect of Lenz's Law when I said:
That friction is Lenz's Law!!!
There! Right there!
I am sorry if I sound a bit annoyed, but I seem to have good reason to be.
Who said I am ignoring the back-EMF? I haven't ignored the circuit from the driver's perspective, not at all. I went to great length explaining it from the driver's perspective. I can't help feeling that you did not read it, that you had already made up your mind. Otherwise why would you say that? May I please suggest that you read it again. By all means make inquiry of the analysis, I don't mind. But please, don't say that something wasn't there when it was!.
I am sorry, but I hardly know of what to make of your comments? Could you be more specific because all I read is a jumble of stuff. What are you really saying?
BTW, since you call me Joe, what should I call you?
Seems that I should know if you are going to criticise me? Fair enough?
So I don't know about Lenz's Law? What? What did I say that makes you think that I don't. I think that every point by point I was observant of Lenz's Law. This is basic stuff. In fact I explained that the effect of Lenz's Law when I said:
That friction is Lenz's Law!!!
There! Right there!
I am sorry if I sound a bit annoyed, but I seem to have good reason to be.
Who said I am ignoring the back-EMF? I haven't ignored the circuit from the driver's perspective, not at all. I went to great length explaining it from the driver's perspective. I can't help feeling that you did not read it, that you had already made up your mind. Otherwise why would you say that? May I please suggest that you read it again. By all means make inquiry of the analysis, I don't mind. But please, don't say that something wasn't there when it was!.
I am sorry, but I hardly know of what to make of your comments? Could you be more specific because all I read is a jumble of stuff. What are you really saying?
BTW, since you call me Joe, what should I call you?
Seems that I should know if you are going to criticise me? Fair enough?
Hi, my name is Teemu but I prefer just the pseudonym online.
My concern is that your message is confusing, for example here
Or this one
Or here, bit earlier denying speaker makes current in the circuit.
Well, in the end your motivation and results end up being the same as Esa's, only your posts and explanations are very confusing. Everyone has right to be confusing and confused, also your customers get the real deal so I guess there is no harm done and I'll leave it here. the claimed "snake-oil" is in the wording only.
Just trying to simplify things. I'm also guilty for confusing posts time to time so...
My concern is that your message is confusing, for example here
which is not true, current doesn't determine position of the cone, it determines force that accelerates the cone. Motional feedback would be needed to control position. Also it says the back-EMF does not correct anything at all, which is partially true. As per Esa's articles showing math its very true on driver resonance, where phase of back-EMF generated current is opposite to current driving it and useful as damping. On the other hand higher up in frequency where voice coil inductance rises this back-EMF current phase is lags and its not useful anymore, but only distortion.
Or this one
I read it direct contradiction to Lenz's law, physics do support brake. If circuit is closed and low enough impedance, there will be current induced into the voice coil that opposes the movement. Its not amplifier braking it, its the driver itself, as you write on later post as well.
Or here, bit earlier denying speaker makes current in the circuit.
Well, in the end your motivation and results end up being the same as Esa's, only your posts and explanations are very confusing. Everyone has right to be confusing and confused, also your customers get the real deal so I guess there is no harm done and I'll leave it here. the claimed "snake-oil" is in the wording only.
Just trying to simplify things. I'm also guilty for confusing posts time to time so...
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Teemu, thank you.
I think I will leave it there. I stand by what I have said and I must be content with the fact that you haven't understood it.
As for Esa, I think I had interchanges a long time ago, I was one of the first that got his book. I also made it cl;ear that I did not agree with many of his conclusions. We agreed to disagree.
Esa is a crusader for current drive...
I AM NOT!!!
NO!!!
At that point I gave up. Can you blame me?
Have you not figured out that I am PRO-Voltage-Drive!
It seems that at any time you talk about current you get put into the current drive camp. But I am NOT in that camp.
I seemed to have been trapped in this strange twilight zone? And I can't get away.
If you read my posts thinking that I was pro-current-drive, it is no wonder that you have so misunderstood them.
Please, with that adjusted view, read them again and it might make more sense to you.
I hope.
I think I will leave it there. I stand by what I have said and I must be content with the fact that you haven't understood it.
As for Esa, I think I had interchanges a long time ago, I was one of the first that got his book. I also made it cl;ear that I did not agree with many of his conclusions. We agreed to disagree.
Esa is a crusader for current drive...
I AM NOT!!!
NO!!!
At that point I gave up. Can you blame me?
Have you not figured out that I am PRO-Voltage-Drive!
It seems that at any time you talk about current you get put into the current drive camp. But I am NOT in that camp.
I seemed to have been trapped in this strange twilight zone? And I can't get away.
If you read my posts thinking that I was pro-current-drive, it is no wonder that you have so misunderstood them.
Please, with that adjusted view, read them again and it might make more sense to you.
I hope.
Hi,
thanks for the response, I shall read some of it again at some point. I'm sorry to bring this up on the thread because its limbo territory for me as well, not having common understanding, but as your message seemed confusing to me and for some others I thought to take on it once more and see if there is clarity to it on this thread.
Its quite clear on other threads and Esa's writings how the stuff works out and I have no issue to utilize "current drive", circuit impedance, on my systems and I see it utilized nicely on your speaker system too. Only grief was your explanations on how it works, but I'm thankful I got confused by your message as it got me to study the subject.
Well, hopefully there is not as much confusion for others, as its not that complicated to take advantage of "current drive". Use good old low output impedance voltage amp and manipulate impedance in the circuit to reap advantages of "current drive".
thanks for the response, I shall read some of it again at some point. I'm sorry to bring this up on the thread because its limbo territory for me as well, not having common understanding, but as your message seemed confusing to me and for some others I thought to take on it once more and see if there is clarity to it on this thread.
Its quite clear on other threads and Esa's writings how the stuff works out and I have no issue to utilize "current drive", circuit impedance, on my systems and I see it utilized nicely on your speaker system too. Only grief was your explanations on how it works, but I'm thankful I got confused by your message as it got me to study the subject.
Well, hopefully there is not as much confusion for others, as its not that complicated to take advantage of "current drive". Use good old low output impedance voltage amp and manipulate impedance in the circuit to reap advantages of "current drive".
Hi Teemu, thanks. Sorry for the extreme emphasis, but I hope you can understand why.
This is a tough subject and it really doesn't belong here, but on the other thread. Please read about the 50 Hertz example on that other thread, and now knowing where I am coming from (not Esa's viewpoint), and I would be really interested in your thoughts. I think that I am pointing out something really useful for those who are into current drive, even if in my case I am not going down that way myself. But it is also a stepping stone to get voltage drive right, but that is a much longer story.
Off to bed.
Cheers, Joe
This is a tough subject and it really doesn't belong here, but on the other thread. Please read about the 50 Hertz example on that other thread, and now knowing where I am coming from (not Esa's viewpoint), and I would be really interested in your thoughts. I think that I am pointing out something really useful for those who are into current drive, even if in my case I am not going down that way myself. But it is also a stepping stone to get voltage drive right, but that is a much longer story.
Off to bed.
Cheers, Joe
Hello All,
There is a Parts Express 0.55 cubic foot sealed enclosure sitting here Today I removed a Purifi 6.5 inch driver and in its’ place I bolted on a SCANSPEAK P17WJ 00 08 driver, an older Vifa design without some of the new technology, still a good driver. The enclosure is sealed tight and has a couple of fistfuls of polyester stuffing.
See the attached Impedance and parameter measurement plots that were measured with the driver attached to the enclosure, note the speaker parameters are calculated with L2R2 model not the standard TS/P.
I like to measure with 2 volts amplifier output. 2 volts is much closer to listening level.
Thanks DT
There is a Parts Express 0.55 cubic foot sealed enclosure sitting here Today I removed a Purifi 6.5 inch driver and in its’ place I bolted on a SCANSPEAK P17WJ 00 08 driver, an older Vifa design without some of the new technology, still a good driver. The enclosure is sealed tight and has a couple of fistfuls of polyester stuffing.
See the attached Impedance and parameter measurement plots that were measured with the driver attached to the enclosure, note the speaker parameters are calculated with L2R2 model not the standard TS/P.
I like to measure with 2 volts amplifier output. 2 volts is much closer to listening level.
Thanks DT
Put my own sample Vifa P17WJ00-08 to the test. Below are free air measurements:
MANUFACTURER Vifa
MODEL P17WJ008
DATE 12-02-2023
Fs 42.9345
Diameter 131.5900
ZMax 39.4298
Re 6.0000
Rms 1.2990
Qms 3.1967
Qes 0.5738
Qts 0.4864
Cms 0.8927
Mms 15.3928
BL 6.5897
VAS 23.0559
dBSPL 87.0475
L1kHz 0.5412mH
L10kHz 0.2863mH
SD 1.36E-02
LCES 38.7652
CMES 354.4750
RES 33.4298
MMD 14.4951
RMT 8.5363
ZMin 6.5992
ZAVG 21.4538
MANUFACTURER Vifa
MODEL P17WJ008
DATE 12-02-2023
Fs 42.9345
Diameter 131.5900
ZMax 39.4298
Re 6.0000
Rms 1.2990
Qms 3.1967
Qes 0.5738
Qts 0.4864
Cms 0.8927
Mms 15.3928
BL 6.5897
VAS 23.0559
dBSPL 87.0475
L1kHz 0.5412mH
L10kHz 0.2863mH
SD 1.36E-02
LCES 38.7652
CMES 354.4750
RES 33.4298
MMD 14.4951
RMT 8.5363
ZMin 6.5992
ZAVG 21.4538
Hi Joe. I shot you an email. Are the kits still available? Usa? Thanks! More questions in email.