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Precision L-Pad


Dave A

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OK tinkering with drivers for my 1.4" throat wood horns and they run up to 109db efficiency whereas the typical woofer seems to be 99 to 100db. So I have an L-Pad from PE I am using to try and take measurements from to establish what resistor values to use. Two things become evident. One is what sounds best to me does not agree with the online L-Pad calculators. Two is getting any accurate measurement down to .01 ohms is pretty hard as the measured values jump around, I guess, according to how many windings are touched when you rotate the knob.

 

  Is there such a thing as precision L-Pads that would eliminate measurement problems? I am finding that with some 904 bass bins (I am guessing on the db efficiency of these K-45's to be around 100db) where I want to add wood horns to even .05 ohms can make an audible difference in the HF side of things.

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Dave,

I have never seen a precision L-Pad.

One of the problems in calculating L-Pad values is that a speaker's impedance varies non-linearly with frequency, and the manufacturer's publish a "nominated" impedance.

One way of getting there would be to measure the system response, determine the tweeter attenuation needed, refer to the manufacturer's impedance curve for the impedance at the passband and use  https://sound-au.com/articles/l-pad-calc.htm to calculate the values needed.  

 

 

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