Frequency response leveller for the 4FE35

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Hello all.

I was wondering if anyone out there could check/critique my work.

I would love to have the frequency response of the 4FE35 to be around 84 DB from 1k upward to 15K.

Using this calculator Strassacker: Speaker Building, Components I think I have the results I wanted. But just wanted someone else to have a look and see. I know I will not get it perfect, and that it is impossible to have it perfect. But I would love to have it around that area.


In the calculator I have ohm set to 4 the frequency set to 6000 and the max db set to 7.5. And I used the curve buttons to expand the curve all the way down to 120 hz. Where it will have .1 db dampening. As you can see in the image below


Thank you for your time!
 

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I think you need a basic baffle step BSC (shelf attenuation) circuit. Roughly speaking, a 0.8mH to 1mH inductor in parallel with 5ohm to 15ohm (depending on how much attenuation you need) should work. If you want to get the 91dB 4FE35 down to 84dB, my guess is that bout 12ohms is needed. Adjust to taste. If you have a mic, measure it and that is best but just start with a base value in ohms and add or subtract until it sounds right.
 
Is your goal here to filter out the peak in frequency response of the 4FE35 at 8kHz? If so, then why did you enter 6kHz?

I've recently used the 16 ohm version of this driver, which has a similar peak at 8kHz, in a transmission line. I used 0.1mH, 3.2uF and 22 ohms for the notch filter. I used an on-line calculator for the initial values, then adjusted them until it measured flat in that 8kHz area. I also used BSC.

These component values won't be correct for your 4 ohm version, but using the calculator you've linked to and it's impedance outputs you could make a comparison.

Graham.
 
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