GREAT article on how speaker works!

[cordura21]

I know this is microphone forum, but it also speak a little about them. Check it out, it's well worth a reading if you're interested in it:

http://www.howstuffworks.com/speaker.htm/printable

cheers, Andrés

 

[Harvey Gerst]

Except for the fact that a lot of the explanations are flat-out wrong (as are the explanations in the microphone links), it's not a bad article.

 

[Dragon]

You've gotten Andrès so upset now that he wants me to pull the thread. I admit I've only scanned the article, but I didn't see too much in the speaker article to quibble over. What's so wrong?

 

[cordura21]

I'm not upset

no, I'm not upset. I just wanted to delete it cause if it's wrong then what's the point of posting it and misguide someone else?
But as Dragon says, this is a great opportunity to learn. Tell as a couple of things that are wrong so I learn from mistakes, which seems to be my default way of learning.

Cheers, Andrés

 

[Harvey Gerst]

For starters, he claims the voice coil in a speaker acts like an electromagnet; it doesn't.

On the microphone links, it claims a ribbon mic consists of a ribbon and a flat plate; it doesn't. Many of the other microphone assertions that are made at least carry warnings that they are not confirmed and may be wrong.

In the picture showing a typical crossover, it says these are inductors and capacitors, whereas the picture shows a capacitor and a couple of resistors, not inductors (which are kind of like one sided transformers).

 

[deaconblues]

I see a few problems (although I agree with Harvey, its not "a bad article").

First, a speaker cone or diaphragm is not "flexible" (at least a decent design minimizes its flexibility), but rather the surround and spider are flexible, which allow the cone to move as a rigid body as much as possible.

While I don't have a problem with calling the voice coil an "electromagnet", the descibed construction is wrong. The voice coil is not wrapped around a piece of metal, but rather is wound on a non-magnetic former that has nothing in the center. The coil is centered on a fixed pole piece in the middle of the permanent magnet (that is drawn incorrectly without the pole piece in the middle).

I think the primary function of a speaker enclosure is really to keep the reverse wave from the speaker driver from cancelling the forward wave. Bass reflex and passive radiator designs are not less precise because of "no air pressure difference to spring the driver back into place", but that the port (or passive radiator) output does not reinforce the driver output the same at different frequencies. This reinforcement is resonant (peaked at one frequency), and a proper design can utilize it to increase the low frequency extension of a loudspeaker system.

my 0.02

 

[Harvey Gerst]

Absolutely right. The voice coil is centered in a gap created by the pole piece and top plate, which bring the magnet's North and South poles to within a few millimeters of the voice coil, creating a strong magnetic field.

A reflex cabinet is designed to behave similar to a tuned coke bottle, usually creating a resonance just below where the speaker starts to roll off, which extends the bass a little more.

There were a lot of similar mistakes and errors all over the place, but still it did help explain how speakers work to a great extent, although I wouldn't use it to design any speakers for myself.

I think I mentioned something about cabinet design in the "big thread", but primarily to help people understand how to mic speaker cabinets better, not to explain how they work in great detail.