I am measuring a woofer inductor taken from a small bookshelf speaker. I've placed a non-inductive 7 ohm resistor across were the speaker is attached. I'm using a calibrated voltage divider setup to measure the impedance.
From 30Hz up, the impedance rises with frequency from 7.5 ohms to about 13 ohms at 2500Hz then drops sharply to a minimum of 3 ohms at 4kHz and then rises again. So it goes inductive, capacitive and inductive. It is not an
air-cored inductor. The inductor is wrapped on a black rod that visually appears to be ferrite. The rod is about 3/8 inch in diameter and about 2 inches long.
Can someone explain the physics of what I am measuring?

"Audio" wrote in message
news:jqptb.157494$275.474621@attbi_s53...
I am measuring a woofer inductor taken from a small bookshelf speaker. I've
placed a non-inductive 7 ohm resistor across were the speaker is attached.
I'm using a calibrated voltage divider setup to measure the impedance.
From 30Hz up, the impedance rises with frequency from 7.5 ohms to about 13
ohms at 2500Hz then drops sharply to a minimum of 3 ohms at 4kHz and then
rises again. So it goes inductive, capacitive and inductive. It is not an
air-cored inductor. The inductor is wrapped on a black rod that visually
appears to be ferrite. The rod is about 3/8 inch in diameter and about 2
inches long.
Can someone explain the physics of what I am measuring?


**What Voltage level are you using? Try the same test at a MUCH lower level.
Let us know what you find.

BTW: You should send your messages in 'plain text' format.


--
Trevor Wilson
www.rageaudio.com.au

"Audio" wrote in message
news:jqptb.157494$275.474621@attbi_s53...
I am measuring a woofer inductor taken from a small bookshelf speaker. I've
placed a non-inductive 7 ohm resistor across were the speaker is attached.
I'm using a calibrated voltage divider setup to measure the impedance.
From 30Hz up, the impedance rises with frequency from 7.5 ohms to about 13
ohms at 2500Hz then drops sharply to a minimum of 3 ohms at 4kHz and then
rises again. So it goes inductive, capacitive and inductive. It is not an
air-cored inductor. The inductor is wrapped on a black rod that visually
appears to be ferrite. The rod is about 3/8 inch in diameter and about 2
inches long.
Can someone explain the physics of what I am measuring?


**What Voltage level are you using? Try the same test at a MUCH lower level.
Let us know what you find.

BTW: You should send your messages in 'plain text' format.


--
Trevor Wilson
www.rageaudio.com.au

The output voltage from the function generator is very low, on the order of
3V. The inductor is soldered to a small circuit board and potted in place.
The tweeter inductor and cap are located in close proximity too but I do not
have the tweeter connected so that part ladder is open. The woofer has the
series inductor and the tweeter has a series cap and parallel (air-core)
inductor for a 2cd order.

Thanks for the reply


"Trevor Wilson" wrote in message
...

"Audio" wrote in message
news:jqptb.157494$275.474621@attbi_s53...
I am measuring a woofer inductor taken from a small bookshelf speaker.
I've
placed a non-inductive 7 ohm resistor across were the speaker is attached.
I'm using a calibrated voltage divider setup to measure the impedance.
From 30Hz up, the impedance rises with frequency from 7.5 ohms to about 13
ohms at 2500Hz then drops sharply to a minimum of 3 ohms at 4kHz and then
rises again. So it goes inductive, capacitive and inductive. It is not
an
air-cored inductor. The inductor is wrapped on a black rod that visually
appears to be ferrite. The rod is about 3/8 inch in diameter and about 2
inches long.
Can someone explain the physics of what I am measuring?


**What Voltage level are you using? Try the same test at a MUCH lower
level.
Let us know what you find.

BTW: You should send your messages in 'plain text' format.


--
Trevor Wilson
www.rageaudio.com.au

The output voltage from the function generator is very low, on the order of
3V. The inductor is soldered to a small circuit board and potted in place.
The tweeter inductor and cap are located in close proximity too but I do not
have the tweeter connected so that part ladder is open. The woofer has the
series inductor and the tweeter has a series cap and parallel (air-core)
inductor for a 2cd order.

Thanks for the reply


"Trevor Wilson" wrote in message
...

"Audio" wrote in message
news:jqptb.157494$275.474621@attbi_s53...
I am measuring a woofer inductor taken from a small bookshelf speaker.
I've
placed a non-inductive 7 ohm resistor across were the speaker is attached.
I'm using a calibrated voltage divider setup to measure the impedance.
From 30Hz up, the impedance rises with frequency from 7.5 ohms to about 13
ohms at 2500Hz then drops sharply to a minimum of 3 ohms at 4kHz and then
rises again. So it goes inductive, capacitive and inductive. It is not
an
air-cored inductor. The inductor is wrapped on a black rod that visually
appears to be ferrite. The rod is about 3/8 inch in diameter and about 2
inches long.
Can someone explain the physics of what I am measuring?


**What Voltage level are you using? Try the same test at a MUCH lower
level.
Let us know what you find.

BTW: You should send your messages in 'plain text' format.


--
Trevor Wilson
www.rageaudio.com.au

"Audio" wrote in message
news:TAvtb.160642$9E1.806626@attbi_s52...
The output voltage from the function generator is very low, on the order
of
3V. The inductor is soldered to a small circuit board and potted in
place.
The tweeter inductor and cap are located in close proximity too but I do
not
have the tweeter connected so that part ladder is open. The woofer has
the
series inductor and the tweeter has a series cap and parallel (air-core)
inductor for a 2cd order.

Thanks for the reply

**Ah, so you're not actually measuring the inductor? When in circuit, you're
actually measuring everything.


--
Trevor Wilson
www.rageaudio.com.au

"Audio" wrote in message
news:TAvtb.160642$9E1.806626@attbi_s52...
The output voltage from the function generator is very low, on the order
of
3V. The inductor is soldered to a small circuit board and potted in
place.
The tweeter inductor and cap are located in close proximity too but I do
not
have the tweeter connected so that part ladder is open. The woofer has
the
series inductor and the tweeter has a series cap and parallel (air-core)
inductor for a 2cd order.

Thanks for the reply

**Ah, so you're not actually measuring the inductor? When in circuit, you're
actually measuring everything.


--
Trevor Wilson
www.rageaudio.com.au