Basic speaker Q

[Phil Allison]

everyone knows the nominal impedance of a cone speaker is slightly
greater
than the DC resistance of the wire used in the voice coil. An nominal 8
ohm
speaker will have about 6 or 7 ohms of DC resistance for example.

Where does the extra 1 or 2 ohms come from ?

***** Skin effect,Brian Goldsmith.

** Hmmm, there *is* a strong magnetic field involved - that might
just deflect the electrons from their usual well trodden paths down the
middle of the wire .....




............. Phil

 

[the swan]

"the swan" <




** At a frequency of 250 to 400 Hz one simply measures the ratio of amps
to volts with a sine wave. This can be by use of a series low ohms shunt
to allow the determination of amps *or* a voltage source fed through a
known series resistor and the speaker and then the ratio of voltages
determined by AC meter reading.

The ratio of impedances is the same as the voltage ratio.

How is the driver mounted? The effect of driver compliance and any
enclosure will affect the impedance measured. This is why I guessed at
"infinite baffle".

 

[Phil Allison]

"the swan" <

how is the driver mounted?

** It barely matters at the frequencies concerned - but assume no
enclosure.




......... Phil

 

[Alan]

Hi to all,


everyone knows the nominal impedance of a cone speaker is slightly greater
than the DC resistance of the wire used in the voice coil. An nominal 8 ohm
speaker will have about 6 or 7 ohms of DC resistance for example.

Where does the extra 1 or 2 ohms come from ?

http://www.epanorama.net/documents/audio/speaker_impedance.html

now, that wasn't hard, was it ???

 

[the swan]

http://www.epanorama.net/documents/audio/speaker_impedance.html

now, that wasn't hard, was it ???

It's pretty much what I said.

 

[Phil Allison]

http://www.epanorama.net/documents/audio/speaker_impedance.html

now, that wasn't hard, was it ???

** I see no specific answer to my original question.

Would you care to spell it out ?



........... Phil

 

[Phil Allison]

"the swan"

It's pretty much what I said.

** Yeah, right.




............. Phil

 

[Mark Hathaway]

1. Vance Dickason, "how to plot and understand Complex Impedance" Speaker
Builder, 1988, page 15.

2. Vance Dickason, Speaker Design Cook Book, fourth Edition

3. R. Small, "Direct Radiating Loudspeaker System Analysis" JAES june 1972

4. Author's Reply to "comments on "an Empirical Model for loudspeaker Motor
Impedance" JAES, Volume 40, no 1. p 43, 1992

5. Author's Reply to "Comments on 'A Model of Loudspeaker Driver Impedance
Incorporating Eddy Currents in the Pole Structure'" Vol. 38, Number 3
pp. 147 (1990) Author: John Vanderkooy

6. A Model of Loudspeaker Driver Impedance Incorporating Eddy Currents in
the Pole Structure Vol. 37, Number 3 pp. 119 (1989) Author: John Vanderkooy

7. http://www.ctc.puc-rio.br/icee-98/Icee/papers/207.pdf

8. http://www.icspat.com/papers/177mfi.pdf



Z = (R^2 + X^2) ^(1/2)

the X term contains all the electrical, mechanical and acoustic impedance
variables


Mark Hathaway

 

[Jeff]

Well iirc... speaker design is a complicated thing

The circuit however is indeed frequency dependant and is a complicated
consisting of Resistance, Inductance and Capacitance (frame)(these last two
things varying with mechanical movement and frequency).

Resistance though is the major contributor, followed by inductance and then
followed by smaller and nasty cocktail of frame capacitance, mechanical cone
resistance ... etc etc. (this last bit is often neglected as its small)

But as R is the major contributor a rough and ready way to measure it with a
DC ohmeter and multiply it by a factor (about 1.2-1.3?)

 

[Rod Speed]

I see no specific answer to my original question.

Maybe you actually are that stupid.

Would you care to spell it out ?

More useful to try explaining it to a stone.

 

[Angelo Sartore]

I have been reading the (sometimes) informative posts from various people
for some time now ... I thank you all.
One 'contributor', Phil Allison, seems hell bent on shit-canning & abusing
anybody & everybody who adds to the various posts.
Has this bloke have a small dick, where he has to fight with everyone?

 

[Phil Allison]

1. Vance Dickason, "how to plot and understand Complex Impedance" Speaker
Builder, 1988, page 15.

2. Vance Dickason, Speaker Design Cook Book, fourth Edition

3. R. Small, "Direct Radiating Loudspeaker System Analysis" JAES june 1972

4. Author's Reply to "comments on "an Empirical Model for loudspeaker Motor
Impedance" JAES, Volume 40, no 1. p 43, 1992

5. Author's Reply to "Comments on 'A Model of Loudspeaker Driver Impedance
Incorporating Eddy Currents in the Pole Structure'" Vol. 38, Number 3
pp. 147 (1990) Author: John Vanderkooy

6. A Model of Loudspeaker Driver Impedance Incorporating Eddy Currents in
the Pole Structure Vol. 37, Number 3 pp. 119 (1989) Author: John Vanderkooy

7. http://www.ctc.puc-rio.br/icee-98/Icee/papers/207.pdf

8. http://www.icspat.com/papers/177mfi.pdf



Z = (R^2 + X^2) ^(1/2)

the X term contains all the electrical, mechanical and acoustic impedance
variables

** Mark - you have posted a load of shite.

The titles of articles are NOT an answer to my question.

NOR is stupidly declaring the answer to be "X".




........... Phil

 

[Phil Allison]

I have been reading the (sometimes) informative posts from various people
for some time now ... I thank you all.
One 'contributor', Phil Allison, seems hell bent on shit-canning & abusing
anybody & everybody who adds to the various posts.
Has this bloke have a small dick, where he has to fight with everyone?

** Got anything useful to say - Angelo ?

Or is posting mindless abuse all you are good for ???



............. Phil

 

[Alan]

** I see no specific answer to my original question.

Would you care to spell it out ?



.......... Phil

Phil,

I'm sorry that your reading and comprehension skills aren't up to the job of
turning the simple explanation in the link that I supplied into an answer to
your question.

Read it a few times, breaking each sentence up into smaller parts that you
are able to understand until it becomes clear. I will refer you specifically
to the sections titled "Speaker model" and "Typical impedance
characteristics of speaker element at different frequencies"

I'm sure everyone else who looked at the link has been able to grasp the
reason behind "the extra 1 or 2 ohms" by now, but keep trying little buddy,
you'll get there eventually !!

 

[Phil Allison]

"Alan" <

Phil,

I'm sorry ...

** You soon will be - you stupid arsehole.

Read it a few times, breaking each sentence up into smaller parts that you
are able to understand until it becomes clear. I will refer you specifically
to the sections titled "Speaker model" and "Typical impedance
characteristics of speaker element at different frequencies"

** I am very familiar with the wording.

I'm sure everyone else who looked at the link has been able to grasp the
reason behind "the extra 1 or 2 ohms" by now,

** Fine - then why don't you fucking *** POST *** it here
??????????????

That article says " .... a variety of reasons.. " for the extra
20% .

That is hardly FUCKING SPECIFIC !!!!!!





............ Phil

 

[Anthony Fremont]

** Fine - then why don't you fucking *** POST *** it here
??????????????

That article says " .... a variety of reasons.. " for the extra
20% .

That is hardly FUCKING SPECIFIC !!!!!!

Well, I guess that's because the extra couple of ohms is due to a
VARIETY of factors, and not just one specific reason. It's an AC
circuit, what else would you expect? There is the impedance of the
wire, the extra inductance of the voice coil, some more reactance added
by the magnet, friction adds some more, and finally the paper cone must
push against the air adding yet more reactance. I suppose that one
could be really pedantic and somehow calculate the effects from the
Earth's magnetic field as well as gravity and add that in too. Even the
insulation on the wire has some effect. At any rate, the 8ohm
"characteristic" impedance is likely only applicable to one specific
frequency and not the entire audio spectrum. What the hell are you
looking for????

 

[Angelo Sartore]

Your a funny guy.

** Got anything useful to say - Angelo ?

Or is posting mindless abuse all you are good for ???



............ Phil

 

[Phil Allison]

Well, I guess that's because the extra couple of ohms is due to a
VARIETY of factors, and not just one specific reason.

** What you "guess" is of no use to anyone.

It's an AC circuit, what else would you expect?

** So this jerk has no idea.

There is the impedance of the wire,

** Huh ?

the extra inductance of the voice coil,


** Not relevant since the phase angle is zero.


( snip shit)

.. At any rate, the 8ohm

"characteristic" impedance is likely only applicable to one specific
frequency and not the entire audio spectrum.

** This complete wanker did not even bother reading the thread.





............ Phil

 

[Steve]

** Got anything useful to say - Angelo ?

Or is posting mindless abuse all you are good for ???



............ Phil

Before this post it was just a personality trait...
Now, hypocrisy is a bona fide art form.

 

[Phil Allison]

"Steve" [email protected]>

Before this post it was just a personality trait...
Now, hypocrisy is a bona fide art form.

** Got anything useful to say - Steve ?

Or is posting mindless abuse all you are good for ???

As with any other Hotmail using fuckwit.




......... Phil