Impedance Chart?

angsuman · 21st May 2006, 06:27 PM

Hey guys i'm trying to figure out how to read an impedance chart that has no ohm markings. For example this one.

I've attached an image of the plot of an audax Audax HP100M0.

I need to trace the impedance plot into passive crossover designer but i can't mark low ohm high ohm with out knowing what each bar represents in ohms. The nominal impedance is 6 ohms.

Thank you and any input is appreciated.

gfinlayson · 21st May 2006, 06:37 PM

As it's a 6 ohm nominal driver, I'd guess that each vertical division is 2 ohms, which would put the impedance peak at 22 ohms at about 82 to 83 Hz.

Original Burnedfingers · 21st May 2006, 06:41 PM

your graph looks like a db level and frequency.
An impedance meter would be nice to check the graph with to see if it follows.

owdi · 21st May 2006, 08:10 PM

The dc resistance (RE) of that speaker should be published. The flat part of the impedance curve between 400hz and 500hz is very close to Re.

Dan

gfinlayson · 21st May 2006, 08:34 PM

Re is 5.7 ohms.

lndm · 22nd May 2006, 02:26 AM

I can't be specific but manufacturers impedance plots I have used typically are logarithmic. Typically doubling each division (2,4,8,16). The resonance peak looks a little rounded rather than pointed and this suggests this plot might be logarithmic too.

BTW, your box will change the bottom end of this plot.

Also, there is no impedance phase data which will be necessary for building a passive crossover.

jbateman · 22nd May 2006, 01:32 PM

Looking at some other Audax graphs implies they scale the impedance trace so that zeo ohms coincides with one of the amplitude lines that end in zero, then each line above that is 5 ohms apart.

angsuman · 22nd May 2006, 08:29 PM

Thank You everyone for your useful replies. Here is a link to the original PDF file. http://www.madisound.com/pdf/audax/hp100m0.pdf

So if i gather correctly the flattest part of the curve is Re?

And the ohm markers are at 2 per each division ?

Or is it logarithmic. See its rather important that i can trace the curve accurately in Passive Crossover Designer.

Again thank you.

lndm · 22nd May 2006, 11:03 PM

As one who isn't sure, could I suggest you mail Audax? They should give you this info.

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21st May 2006, 06:37 PM	#2
gfinlayson diyAudio Member Join Date: Jan 2006 Location: Aylesford, Kent, England	As it's a 6 ohm nominal driver, I'd guess that each vertical division is 2 ohms, which would put the impedance peak at 22 ohms at about 82 to 83 Hz.

21st May 2006, 06:41 PM	#3
Original Burnedfingers diyAudio Member Join Date: Nov 2002	your graph looks like a db level and frequency. An impedance meter would be nice to check the graph with to see if it follows.

21st May 2006, 08:10 PM	#4
owdi diyAudio Member Join Date: Sep 2003 Location: Bellevue, WA	The dc resistance (RE) of that speaker should be published. The flat part of the impedance curve between 400hz and 500hz is very close to Re. Dan

21st May 2006, 08:34 PM	#5
gfinlayson diyAudio Member Join Date: Jan 2006 Location: Aylesford, Kent, England	Re is 5.7 ohms.

22nd May 2006, 02:26 AM	#6
lndm diyAudio Member Join Date: Mar 2006 Location: nsw	I can't be specific but manufacturers impedance plots I have used typically are logarithmic. Typically doubling each division (2,4,8,16). The resonance peak looks a little rounded rather than pointed and this suggests this plot might be logarithmic too. BTW, your box will change the bottom end of this plot. Also, there is no impedance phase data which will be necessary for building a passive crossover.

22nd May 2006, 01:32 PM	#7
jbateman diyAudio Member Join Date: Oct 2000 Location: The People's Republic of Maryland	Looking at some other Audax graphs implies they scale the impedance trace so that zeo ohms coincides with one of the amplitude lines that end in zero, then each line above that is 5 ohms apart.

22nd May 2006, 08:29 PM	#8
angsuman diyAudio Member Join Date: Mar 2005 Location: Las Vegas NV	Thank You everyone for your useful replies. Here is a link to the original PDF file. http://www.madisound.com/pdf/audax/hp100m0.pdf So if i gather correctly the flattest part of the curve is Re? And the ohm markers are at 2 per each division ? Or is it logarithmic. See its rather important that i can trace the curve accurately in Passive Crossover Designer. Again thank you.

22nd May 2006, 11:03 PM	#9
lndm diyAudio Member Join Date: Mar 2006 Location: nsw	As one who isn't sure, could I suggest you mail Audax? They should give you this info.

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