Help with wiring colors on old headphones

"Ian Jackson" Phil Allison

A pin may well be attracted by the magnet.

Testing a ( moving coil) driver with a battery establishes a polarity that is the reverse of the "real" one during normal operation.

The *actual cone motion* in response to alternating current drive (within a driver's operating band) involves a double integration of the current ave - hence a 180 degree phase shift.

The same fact also means that a cone reproducing a square wave ( within it's operating band ) follows a motion very close to that when reproducing a sine wave at the same fundamental frequency. IOW the third and higher order odd harmonics of the square wave cause very little actual cone motion.

Bet anything this starts an argument.

... Phil

it's

sine

There's no argument. As a degreed EE, I'm reasonably certain everything Mr Clavin here has said is either wrong or a misinterpretation.

The claim of polarity inversion could easily be checked by monitoring the speaker's output with a mic of known polarity. Or is Cliffy going to claim that mics, too, have the "wrong" polarity?

There are two likely points of confusion. First, the current flow through an inductor lags the voltage across the inductor by 90 degrees. (How a "double integration" occurs is not immediately obvious.) Second, most cone-type drivers are more resistive than reactive, so you're not going to get 90 degrees, anyway.

Assuming (incorrectly) that the driver were wholly inductive, a double integration of the current would cause the current to fall at 12dB/8ve. Assuming the driver is working "constantly velocity", you'd still wind up with a 6dB/8ve net rolloff. (I think.)

I have no objection to someone saying "Everything you know is wrong!". I do it all the time. But no one ever gives ME serious consideration, even when I'm dead right. Cliff, here, should be grateful I treated his claims with a degree of seriousness. It's far, far more than he deserves.

"William Sommerwanker is a colossal F****IT"

( snip)

The point is entirely about * cone excursion* above resonance as a function of drive frequency for fixed AC drive voltage. Obviously a cone does not follow the actual drive voltage wave - or the excursion and all frequencies would be the same.

Once you work out the simple relationship is between drive frequency and cone excursion when the cone's mass dominates the game - you have it.

.... Phil

function

frequencies

How dare you answer a criticism courteously -- what's the world coming to?

I'll check my books on acoustics about this.

Check your physics book, too, recalling (as Phil said), that a speaker is a mechanical system operating *above resonance*.

You can simulate this by hanging a fairly heavy weight from a rubber band. Hold the other end of the band (with the weight hanging down, stretching the rubber but *not too much*). Move your hand up and down. Below resonance, the weight follows your hand, with constant displacement, no matter the frequency. Above resonance, your hand goes down while the weight is coming up, and the faster you move your hand, the smaller the weight's excursion gets. That's the domain a speaker works in.

It is this reduction in excursion as frequency increases that makes a speaker *automatically* have a constant volume velocity (constant output level) regardless of frequency. The cone excursion drops by a factor of four for every octave increase in frequency.

But insofar as speaker phasing is concerned, as long as they are both the same, it doesn't matter much, because in general, you have no idea what happened to the signals before they got stuck on that CD (or whatever).

Isaac

"isw"

BTW:

The situation is different for most headphones and electrostatic speakers - where diaphragm movement is resistance dominated rather than mass dominated.

Plus different again for a condenser microphone where diaphragm excursion does not vary with frequency and the output voltage wave is a direct replica of its displacement from zero.

.... Phil