Is it possible to measure Impedance with an ohm meter.
For example can you measure the Impedance of a 4 ohm
car speaker with an ohm meter?

When I tell people they cannot measure Impedance with an
ohm meter, you need an impedance meter and the impedance
must be measured with the speaker in operation, with a signal generator
supplying a fixed frequency, this always leads to disagreements
with the person who demands an ohm meter to measure what he calls
Impedance, when I tell him an ohm meter can only measure the resistance
of the coil there is always disagreement.

I tell them Impedance is AC resistance and what they measure
with an ohm meter is DC resistance. Disagreement here again.

Will somebody take me up on this and clarify the situation.

Thanks in advance
Denny B

In article , Denny B
wrote:
Is it possible to measure Impedance with an ohm meter. For example can
you measure the Impedance of a 4 ohm car speaker with an ohm meter?

Yes. You can measure the impedance *at zero Hz* (d.c.) that way. Generally
called the resistance. :-)

When I tell people they cannot measure Impedance with an ohm meter, you
need an impedance meter and the impedance must be measured with the
speaker in operation, with a signal generator supplying a fixed
frequency, this always leads to disagreements with the person who
demands an ohm meter to measure what he calls Impedance, when I tell him
an ohm meter can only measure the resistance of the coil there is always
disagreement.

People believe all sorts of things. ;-

I tell them Impedance is AC resistance and what they measure with an ohm
meter is DC resistance. Disagreement here again.

Will somebody take me up on this and clarify the situation.

See the above. I'd say you are basically correct, and they are wrong. By
all means suggest they have a look at the 'Scots Guide' website (URL in my
sig) if you think this will help them. However if they won't take your word
for it, I am not sure they will take mine, either. Perhaps you can suggest
they buy and read a copy of Horowitz and Hill?

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

"Denny B" wrote in message
...
Is it possible to measure Impedance with an ohm meter.
For example can you measure the Impedance of a 4 ohm
car speaker with an ohm meter?

When I tell people they cannot measure Impedance with an
ohm meter, you need an impedance meter and the impedance
must be measured with the speaker in operation, with a signal generator
supplying a fixed frequency, this always leads to disagreements
with the person who demands an ohm meter to measure what he calls
Impedance, when I tell him an ohm meter can only measure the resistance
of the coil there is always disagreement.

I tell them Impedance is AC resistance and what they measure
with an ohm meter is DC resistance. Disagreement here again.

Will somebody take me up on this and clarify the situation.

Thanks in advance
Denny B




yes denny you are correct, further loudspeakers have a changing impedance
with frequency so an impedance meter for this use will have a few spot
frequencies built in to it.

a D.C ohm meter is traditionally used to do a quick and dirty check of
loudspeaker drive units however, mainly because an impedance meter is a
costly item, especially for infrequent use.
regards bob

" Is it possible to measure Impedance with an ohm meter.

No.

For example can you measure the Impedance of a 4 ohm
car speaker with an ohm meter?

No again it is a AC measurement as you say and an Ohm meter measures DC
resistance ONLY

When I tell people they cannot measure Impedance with an
ohm meter, you need an impedance meter and the impedance
must be measured with the speaker in operation, with a signal generator
supplying a fixed frequency,

Slightly incorrect the measurement of a speakers impedance is a average over
the frequency range of the expected use of the speaker.

when I tell him an ohm meter can only measure the resistance
of the coil there is always disagreement.

Huh they are wrong.

Steve

I bought a Maplins meter for my son and it has an impedence range on it.
So???????

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

In article ,
Andy Evans wrote:
I bought a Maplins meter for my son and it has an impedence range on it.
So???????

Maplin don't sell a stand alone impedance measuring meter - or at least
not last time I looked. Care to give its part number?

--
*Acupuncture is a jab well done.*

Dave Plowman London SW 12
RIP Acorn

"Denny B" wrote in message


Is it possible to measure Impedance with an ohm meter.

Only at DC.

For example can you measure the Impedance of a 4 ohm
car speaker with an ohm meter?

Ironically, most speakers have a nominal impedance that is about the same or
a tad more than their DC resistance. A 4 ohm car speaker will have a DC
resistance that is close enough to 4 ohms to convince most people.

When I tell people they cannot measure Impedance with an
ohm meter, you need an impedance meter and the impedance
must be measured with the speaker in operation, with a signal
generator supplying a fixed frequency, this always leads to
disagreements with the person who demands an ohm meter to measure
what he calls Impedance, when I tell him an ohm meter can only
measure the resistance of the coil there is always disagreement.

You're right. They are wrong, at least in theory.

I tell them Impedance is AC resistance and what they measure
with an ohm meter is DC resistance. Disagreement here again.

You're right. They are wrong, at least in theory.

Will somebody take me up on this and clarify the situation.

The ironic part is that the DC resistance of most speakers is close to the
nominal impedance.