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.

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

Thanks in advance
Denny B

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?

You can measure the DCR with an ohmmeter, and from there deduce the
impedance. So yes, if you want to know a speaker's impedance, an ohmmeter
is the way to go. With a reactive load like a loudspeaker, there's
technically no such thing as a single value for an impedance anyway. When
we talk about "4 ohm speakers", they're usually only close to 4 ohms in a
limited bandwidth, and even then it's often +/-20%.

I see 4 ohm speakers fluctuate in ohm readings between 3.6 ohms and 4.7ohms

"Mark Zarella" seesigfile 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?

You can measure the DCR with an ohmmeter, and from there deduce the
impedance. So yes, if you want to know a speaker's impedance, an ohmmeter
is the way to go. With a reactive load like a loudspeaker, there's
technically no such thing as a single value for an impedance anyway. When
we talk about "4 ohm speakers", they're usually only close to 4 ohms in a
limited bandwidth, and even then it's often +/-20%.

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?

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.

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

Thanks in advance
Denny B



The coil resistance dominates so you can estimate a speaker's average
impedance with an ohm meter. It's good enough for matching speakers to
amps but I wouldn't trust it for designing a finely tuned crossover.

You are correct. Impedance is an "AC resistance" and will vary with
frequency.

"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.

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

Thanks in advance
Denny B

I see 4 ohm speakers fluctuate in ohm readings between 3.6 ohms and
4.7ohms

The DC resistance should not be fluctuating. It rises during operation as
the coil heats up, but when you're measuring a cool coil a "4 ohm" speaker
should have a DCR of anywhere between 3.3 and 3.8 ohms, typically.

I didn't mean fluctuate when testing it. I meant just the varation of
speakers give different readings.

"Mark Zarella" seesigfile wrote in message
...
I see 4 ohm speakers fluctuate in ohm readings between 3.6 ohms and
4.7ohms

The DC resistance should not be fluctuating. It rises during operation as
the coil heats up, but when you're measuring a cool coil a "4 ohm" speaker
should have a DCR of anywhere between 3.3 and 3.8 ohms, typically.

an OHM meter will only give you the DC resistance of the
speaker, NOT the actual impedance....

I show how to do it on this web page
http://www.installer.com/tech/sit.html

the impedance of a speaker WILL VARY depending on what
frequency you put into it, since the OHM meter uses a
battery to get your mesurement the frequency in that case is
ZERO Hz.....

Dont forget a speaker can be 5ohms at one frequency and
15ohms at another frequency.. (THIS IS NORMAL!)
And ohm meter cannot tell you this...

good luck
Eddie Runner
http://www.installer.com/tech/

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?

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.

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

Thanks in advance
Denny B

IT WILL FLUCTUATE if anyone pushed the woofer cone!!!

Eddie

Mark Zarella wrote:

I see 4 ohm speakers fluctuate in ohm readings between 3.6 ohms and
4.7ohms

The DC resistance should not be fluctuating. It rises during operation as
the coil heats up, but when you're measuring a cool coil a "4 ohm" speaker
should have a DCR of anywhere between 3.3 and 3.8 ohms, typically.

well that's a given. but nobody is. . .


"Eddie Runner" wrote in message
...
IT WILL FLUCTUATE if anyone pushed the woofer cone!!!

Eddie

Mark Zarella wrote:

I see 4 ohm speakers fluctuate in ohm readings between 3.6 ohms and
4.7ohms

The DC resistance should not be fluctuating. It rises during operation
as
the coil heats up, but when you're measuring a cool coil a "4 ohm"
speaker
should have a DCR of anywhere between 3.3 and 3.8 ohms, typically.

Hi,
Real impedance can be measured with impedance bridge but meter will give
an idea. Typically meter reading is close to rated impedance. As an
example 4 Ohm one will read on the meter 3.something, 8 Ohm will read 6.
something, etc. Impedance is frequency dependent so, rated value is in
reference to certain frequency, like at 1KHz or 3 KHz. You'll see it on
Impedance vs. frequency curve.
Tony

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?

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.

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

Thanks in advance
Denny B

I didn't realize he was pushing the cone while making the measurement.
That's an awfully strange thing to do...

--
Mark Zarella
zarellam at upstate dot edu


"Eddie Runner" wrote in message
...
IT WILL FLUCTUATE if anyone pushed the woofer cone!!!

Eddie

Mark Zarella wrote:

I see 4 ohm speakers fluctuate in ohm readings between 3.6 ohms and
4.7ohms

The DC resistance should not be fluctuating. It rises during operation
as
the coil heats up, but when you're measuring a cool coil a "4 ohm"
speaker
should have a DCR of anywhere between 3.3 and 3.8 ohms, typically.