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Increase total Speaker Impedance Question

Hi All,

I got a tech question. I have built a pair of speaker using a unique crossover for each speaker. Based on my test, if I parallel wire them, the resulting frequencies are correct, but resulting frequencies are NOT correct when I tried to wire several speakers as a series (series-parallel wiring). I suspect that because series wiring requires daisy chaining two or more crossovers, the resulting frequencies are messed up. However, if I retain current parallel wiring, the total impedance of the speaker system is too low and the amplifier often goes into protection mode. Is there anyway to add a resistor in between the amp and the speaker to rectify the situation? And if I do add a resistor, will that affect the sound quality? Thanks!!
angelgz2
bill_k
880 posts
 
If you combine four speakers by connecting two in parallel and two in series, you will end up with the total impedance equaling the impedance of a single speaker. You can see this by using this calculator and selecting "2 series and 2 parallel" and entering the correct impedance values. If you added a series resistor to increase impedance, it would have to be a power resistor able to dissipate the wasted power it would use in heat, and it would affect the sound. Hope that this helps!
almarg's avatar
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almarg
9,670 posts
 
Good comments by Bill, as always.

I'll add that connecting speakers in series will usually result in poor sonics unless the speakers are identical models. The voltage and power put out by the amplifier will divide up between series connected speakers based on the relation between their impedances. If the two speakers are identical the voltage and power put out by the amplifier at any instant of time will divide up equally between them. If they are not identical models, the relation between their impedances will almost always be significantly different at different frequencies, resulting in the voltage and power put out by the amplifier dividing up between them differently at different frequencies, resulting in arbitrary frequency response irregularities in each speaker, as you found.

Regards,
-- Al
bill_k
880 posts
 
In my response above I was assuming that the four speakers each have identical impedance values. Thanks to Al for kindly confirming my input, as I consider him to be the true authority on any technical issues.
angelgz2 OP
42 posts
 
Thank you all for your response and help. Yes, all of the speakers are different models and hence each have its own unique crossover that I ordered from Parts Express. As a results the only way to make it sonically plausible is to wire them in a parallel. However, the current parallel wiring has reduced the total Ohm to 1.6, too dangerous for the amplifier to handle. I have ordered two 3 ohm wirewound resistor rated at 200 watt. It will be placed between the receiver and the speakers. Would that seriously damage sound quality? I'll try it either way and let you know how it turns out. Thanks!!
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