Audio Pro had something similar, right?
audiosciencereview.com
Not quite, correct phrase would have been:
Sums it up nicely thanks, lowering the output impedance of the amplifier does make a difference.
Until a certain point. Law of diminishing returns.
Induced EMF voltage is the same polarity, but current (responsible for braking) is in the opposite direction from the speaker to the amplifier. This current is equal induced EMF voltage divided by total impedance in the circuit - speaker coil + cable + amplifier (all in series). When speaker is about 6 ohm it won't make much difference in braking if amplifier's output impedance is 0.1ohm (6.1ohm total) or 0.01ohm (6.01 ohm).
This is an approach that is idealized and in reality the 6Ohm is not fixed because each turn of the voice coil couples individually and proportionately during movement, so the resistance is distributed.
Braking current is inversely proportional to total impedance in the circuit.
The formula is -e = L x (di/dt) the - indicates the direction of the induced EMF.
They are just terminal markings indicating the correct supply polarity. Under back fed induced EMFs the indicated polarity is incorrect.
The formula you quoted is likely for the circuit with battery switch and inductor. Here back EMF is a result of the motion of the membrane inducing voltage. Again, in order for induced current to brake the motion it has to flow in direction that makes opposite motion of the membrane. If current causing forward motion of the membrane flows from + to - terminals inside of the speaker in order to brake motion of the membrane moving on its own it has to flow in the opposite direction thru the speaker, from - terminal to + terminal. This will only happen if induced back EMV voltage has the same polarity. Current will flow from + speaker terminal thru the amp back to - speaker terminal. Inside of the speaker it will flow from - to + terminals.
As you already repeated this same message for more than 10 times in different topics (often including the same link to some vague text), can you explain what it means and what the exact impact on speaker driver damping is?
It doesn’t matter Lenz’s law applies to all inductive circuits. To put it another way an inductive load will oppose any change in rise or fall in circuit current. They are also known as ‘Chokes‘ as they will oppose any rise in circuit current.
Lenz's law only states that the polarity of the induced EMF is such, that it produces a current whose magnetic field opposes the change which produces it. That implies that EMF current has to flow in the opposite direction thru the speaker (to create opposite motion). In order for this to happen polarity of EMF has to be the same (because current now flows not from amp to speaker but from the speaker to amp).
Congratulations you’ve just rewritten one of the Scientific rules. Although your tests leave a little to be desired?
Please conduct this test yourself and speak later. I'm not sure why it is so hard to understand that braking current has to flow in opposite direction to current causing motion (that's what Lenz says). In order for this to happen voltage generated by the membrane motion has to be the same as voltage applied that causes motion in the same direction. You have to think, instead of quoting laws that you clearly don't understand. I had big hopes, that experiment might finally convince you, but I see it is hopeless. I'm out.
