Series Resistor for attenuation in Passive Crossover

[Eddie Wolve]

Hi all.

Can someone varify my maths here...(it's been a while)

I wish to provide about 7dB attenuation for a horn tweeter. (8 ohms) using a non-inductive series resistor. (not L pad)

My intention is to increase the overall impedance of the tweeter / attenuation, so as to allow me to use lower value capacitors (therefore cheaper) in the passive crossover which will be 18dB/ Octave.

My calculations are a resistor of about 10 ohms will be required..

Any comments appreciated...

Ed.

 

[godfrey]

Your calculation would be correct if the tweeter's impedance was really 8 ohms. To get the crossover design right, you need to get a graph of your tweeter's impedance vs frequency.

 

[Eddie Wolve]

Thanks Godfrey..

The problem you mention is a problem with ALL passive crossovers is it not..?

Usually adressed by impedance EQ circuits etc..?

I guess off the top of my head, an L pad 'might' be less susceptible, as it has a purely resistive load in parallel to the driver..?

 

[godfrey]

Yes, sometimes and yes.

A transformer could be useful too, with it's inductance forming part of the filter.