[[email protected]]

Trevor wrote: "In any case ALL speakers vary wildly in *impedance* across the frequency
range, especially ported speakers, but"

So given that, the question should be, are mfgs listing the avg, max, or min impedance on the cabinet spec sticker?

[chuck]

On Thu, 4 Dec 2014 05:10:48 -0800 (PST), wrote:

Trevor wrote: "In any case ALL speakers vary wildly in *impedance* across the frequency
range, especially ported speakers, but"

So given that, the question should be, are mfgs listing the avg, max, or min impedance on the cabinet spec sticker?


Since there is no standard, the manufacturers can list whatever
impedance they want; within the range of impedances that the speaker
has in its frequency range. For example, some speakers rated at 4
ohms dip below 2 ohms at certain frequencies.

[[email protected]]

chuck:

That's the problem: No standards. I was told about some standard for audio(measurement) that was abandoned in the '70s or thereabouts. Forgot the name of it.

[Trevor]

On 5/12/2014 2:42 AM, wrote:
chuck:

That's the problem: No standards.
I was told about some standard for audio(measurement) that was
abandoned in the '70s or thereabouts.
Forgot the name of it.


The great thing about standards is there are so many to choose from! :-)

Trevor.

[[email protected][_2_]]

On Thursday, December 4, 2014 7:10:40 PM UTC-7, Trevor wrote:
On 5/12/2014 2:42 AM, wrote:
chuck:

That's the problem: No standards.
I was told about some standard for audio(measurement) that was
abandoned in the '70s or thereabouts.
Forgot the name of it.


The great thing about standards is there are so many to choose from! :-)

Really?How many standards for the measurement of loudspeakers
(ignoring national adoptions of the widely accepted ones) are
there?

Dick Pierce

[Trevor]

On 17/12/2014 1:14 AM, wrote:

Welcome back Dick!


On Thursday, December 4, 2014 7:10:40 PM UTC-7, Trevor wrote:
On 5/12/2014 2:42 AM, wrote:
chuck:

That's the problem: No standards.
I was told about some standard for audio(measurement) that was
abandoned in the '70s or thereabouts.
Forgot the name of it.


The great thing about standards is there are so many to choose from! :-)

Really?How many standards for the measurement of loudspeakers
(ignoring national adoptions of the widely accepted ones) are
there?

Sorry Dick, it was just a joke, hence the smiley.
(although a well used joke that does apply in many cases)
You are quite correct of course about the accepted standards for speaker
measurement, and the fact they are often ignored by many manufacturers.

Trevor.

[Peter Larsen[_3_]]

"Trevor" skrev i en meddelelse
...

On 17/12/2014 1:14 AM, wrote:

Welcome back Dick!

+1

Trevor.

Kind regards

Peter Larsen

[[email protected][_2_]]

On Thursday, December 4, 2014 8:42:57 AM UTC-7, wrote:
chuck:

That's the problem: No standards.

Nope, IEC 60268-5 (and its predecessor IEC 268-5) has been in effect
for decades and is quite current. There are any number of nationalized
versions of the same standard as well.

I was told about some standard for audio(measurement) that
was abandoned in the '70s or thereabouts.

No, it was never "abandoned" by anyone. Any number of manufacturers
may fail to follow it, but it is hardly abandoned.

Forgot the name of it.

IEC 60268-5

Dick Pierce

[geoff]

On 5/12/2014 4:40 a.m., chuck wrote:
On Thu, 4 Dec 2014 05:10:48 -0800 (PST), wrote:

Trevor wrote: "In any case ALL speakers vary wildly in *impedance* across the frequency
range, especially ported speakers, but"

So given that, the question should be, are mfgs listing the avg, max, or min impedance on the cabinet spec sticker?


Since there is no standard, the manufacturers can list whatever
impedance they want; within the range of impedances that the speaker
has in its frequency range. For example, some speakers rated at 4
ohms dip below 2 ohms at certain frequencies.



Some do specify a 'minimum impedance', and some even at what frequency
that occurs. And the minimum *is* the most relevant.


geoff

[[email protected]]

On Thursday, December 4, 2014 8:40:49 AM UTC-7, chuck wrote:
On Thu, 4 Dec 2014 05:10:48 -0800 (PST), wrote:
So given that, the question should be, are mfgs listing the
avg, max, or min impedance on the cabinet spec sticker?


Since there is no standard,

Wrong, there has been in existence for several decades, a widely
accepted standard for measuring ans specifying impedance. IEC
60268-5:
16 Impedance and Derivative Characteristics
16.1 Rated impedance - characteristic to be specified
NOTE This is a rated condition in accordance with 3.2.1.
The lowest value of the modulus of the impedance in the
rated frequency range shall be not less than 50% of the
rated impedance. If the impedance at any frequency
outside this range (including d.c.) is less than this
value, this shall be stated in the specifications.
16.2 Impedance curve
16.2.1 Characteristics to be specified
The impedance curve shall be specified, with represen-
tation of the modulus of the impedance as a function of
frequency.
16.2.2 Method of measurement
16.2.2.1 The loudspeaker shall be brought under normal
measuring conditions in accordance with 3.2.2
conditions a), b), and d).
16.2.2.2 A constant voltage or current shall be supplied,
the former usually being preferred. The value of voltage
or current chosen for the measurement shall be sufficiently
small to ensure that the loudspeaker operates in a linear
region.
Note Measurement of impedance may be strongly influenced
by drive level. If the level is either too low or too
high, inaccurate results may be obtained. The data should
be examined for consistency at several drive levels in
order to establish the best conditions.
16.2.2.3 The modulus of impedance shall be measured at least
over the range of 20 Hz to 20 000 Hz.
16.2.2.4 The results shall be presented graphically as a
function of frequency. The value of the voltage or the
current shall be stated with the results.

the manufacturers can list whatever impedance they want;

Well, more accurately: the manufacturers can choose to ignore
common, well established and agreed upon standards and can
thus make up any damned number they want. Unfortunately,
not a few do just that.

within the range of impedances that the speaker
has in its frequency range. For example, some speakers rated at 4
ohms dip below 2 ohms at certain frequencies.

And, if they so choose to follow the standard, they must state so.

Dick Pierce

[Trevor]

On 5/12/2014 12:10 AM, wrote:
Trevor wrote: "In any case ALL speakers vary wildly in *impedance* across the frequency
range, especially ported speakers, but"

So given that, the question should be, are mfgs listing the avg, max, or min impedance
on the cabinet spec sticker?

The simple answer to that is no (unless by chance), no, and some.

Trevor.