How do you calculate loudspeaker total impedance - diyAudio
 How do you calculate loudspeaker total impedance
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 Multi-Way Conventional loudspeakers with crossovers

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 8th October 2014, 11:57 PM #1 diyAudio Member   Join Date: May 2006 How do you calculate loudspeaker total impedance Hi I was wondering how to calculate the total impedance of 3-way loudspeaker? So, that is the impedance what the amplifier sees. The drivers are connected in parallel ? So if you have 3 parallel 8ohm drivers so they would combine total of 2.67 ohms?
 9th October 2014, 12:09 AM #2 diyAudio Member     Join Date: Dec 2004 Location: Novi, Michigan Put simply yes. But the real impedance is anything but flat, so your simple example is just that, very simplified. __________________ Earl Geddes Gedlee Website Read about the highly acclaimed Geddes loudspeakers
diyAudio Member

Join Date: Apr 2011
Location: Upper midwest
Quote:
 Originally Posted by Sape Hi I was wondering how to calculate the total impedance of 3-way loudspeaker? So, that is the impedance what the amplifier sees. The drivers are connected in parallel ? So if you have 3 parallel 8ohm drivers so they would combine total of 2.67 ohms?
Don't forget that there are crossover components as well. Check out some Stereophile on-line speaker reviews,
they plot speaker system impedance and phase. Usually, each driver in the speaker system has some crossover
components between it and the amplifier, and the inputs to these driver circuits are all connected in parallel
for the amplifier to drive. Sometimes other ways are used to connect the components, though.

Last edited by rayma; 9th October 2014 at 12:32 AM.

 9th October 2014, 12:51 AM #4 diyAudio Member     Join Date: Sep 2003 Location: SiliconValley In the Beginning, God created Spice, and all was good. Loudspeakers and crossovers were modeled in Spice before SPL traced based crossover design tools became freely available. There are a few tutorials on how to use the speaker T/S parameters to create a decent Spice model. You can use LTSPICE with a simple amplifier model to get impedance vs. frequency, phase, even SPL vs. freq with your crossover. Good for early paper design work.... before you take out a mic and measure all of your speakers in the cabinet for detailed SPL data for final simulation. ===================== Computer-Aided Electroacoustic Design with Spice W. Marshall Leach users.ece.gatech.edu/mleach/papers/spice_electro.pdf http://micka.de/org/en/download/spice-tsp_en.pdf www.micka.de/org/download/spicetsp.asc.zip Another article on modelling of loudspeaker impedance: ePanorama.net | Audio | Video | Circuits | Electronics Design Measuring Loudspeaker Driver Parameters Loudspeakers
diyAudio Member

Join Date: Jan 2014
Location: Macedonia
Quote:
 Originally Posted by Sape Hi I was wondering how to calculate the total impedance of 3-way loudspeaker? So, that is the impedance what the amplifier sees. The drivers are connected in parallel ? So if you have 3 parallel 8ohm drivers so they would combine total of 2.67 ohms?
3-way loudspeakers means 3 different drivers with high-pass or low-pass (or both - for midrange) filter on each driver, and all combined in parallel (forget for this moment the serial crossover). Total impedance is a bit misleading, because the lowest impedance is what realy is counting (is more important). So, if the mid is 4-ohm and woofer and tweeter are 8-ohm, than the whole loudspeaker should be 4-ohm nominal impedance.
For sure if you put 8-ohm 3 drivers (without filters) in parallel, than you have 2.67-ohm loudspeaker.

diyAudio Member

Join Date: Dec 2004
Location: Novi, Michigan
Quote:
 Originally Posted by LineSource In the Beginning, God created Spice, and all was good.
Thank goodness we have moved on quite a bit from there. Spice never could do a good job of modeling a loudspeaker.

Sin Bin

Join Date: Nov 2003
Location: Brighton UK
Quote:
 Originally Posted by gedlee Put simply yes. But the real impedance is anything but flat, so your simple example is just that, very simplified.
Hi,

Put simply no, not in the slightest. 3 8 ohm drivers
in a 3 way speaker = an 8 ohm speaker, not 2.67.

Doesn't matter whether the x/o is series or parallel.

rgds, sreten.

In reality unless you screw up the x/o the speakers
impedance is determined by the low bass section.

Last edited by sreten; 9th October 2014 at 01:51 AM.

diyAudio Member

Join Date: Apr 2011
Location: Upper midwest
Quote:
 Originally Posted by sreten Put simply no, not in the slightest. 3 8 ohm drivers in a 3 way speaker = an 8 ohm speaker, not 2.67.
Yes, in practice with a proper crossover this is true, but he didn't understand that there's a crossover network necessary,
so in his terms, he was right.

Last edited by rayma; 9th October 2014 at 01:59 AM.

 9th October 2014, 01:57 AM #9 Sin Bin   Join Date: Nov 2003 Location: Brighton UK Hi, The OP asked if the drivers are in parallel, no they are not. So the next question, that means its 2.67 ohms is wrong. rgds, sreten.
 9th October 2014, 02:12 AM #10 diyAudio Member     Join Date: Dec 2004 Location: Novi, Michigan sreten - Really? you are going to lecture me on how to calculate parallel impedances? You can be a real pip sometimes! __________________ Earl Geddes Gedlee Website Read about the highly acclaimed Geddes loudspeakers

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