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Multi-Way Conventional loudspeakers with crossovers

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Old 14th October 2011, 03:44 PM   #11
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Location: The Netherlands, near the German border
Originally Posted by Conrad Hoffman View Post
IMO, you won't find any great difference in practical performance between a cheap hand wound 0.15 mH inductor made of wire and a boutique foil component. Also, I'd never buy a foil inductor from anybody that wouldn't tell me the Q and the self-resonant frequency up front without having to buy the thing and measure it.
Professionally I wouldn't either, but as this is a hobby and I like experimenting with these kinds of things it's not a problem. Especially the very low DCR of this coil is interesting for me. I want to use it to make a notch to control the resonance of a mid bass driver, the rest of the system is fully active (Samson 3 way x-over 24dB LR + modified Behringer DEQ2496 and a bunch of LM3886 based amps).

This setup is already working very nicely with a Seas U18RNX/P woofer which doesn't require a notch. (tweeter is a ScanSpeak version of the XT25) I know I can also make the notch part of the active circuitry but this would require (a lot) more effort.

I have experience in designing filters for TV applications (mainly IF filters) so a notch filter for audio frequencies shouldn't be a problem. That is, if all the data is available...

Anyway I am rambling, thank you all for your input!
Music is art - Audio is psychoacoustics & engineering
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Old 14th October 2011, 03:54 PM   #12
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Location: Canandaigua, NY USA
A man after my own heart- after all, measurement is fun! FWIW, I've also seen improvements at certain values and frequencies by winding coils with the right Litz wire.
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Old 14th October 2011, 10:16 PM   #13
AllenB is offline AllenB  Australia
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Originally Posted by Mark.Clappers View Post
I have experience in designing filters for TV applications (mainly IF filters)
Speaker inductors are practically close to the ideal component. If you are curious, put some resistance (0k1 -10k?) in series with the winding and sweep it (maybe into the low MHz range) watching for the peak, preferrably on a scope. I wouldn't bother with the smaller values like this one.... mains transformer primaries usually show this peak, often near the upper audio band. This is where I usually use this test either when damping the windings of a power transformer or finding suitable output transformers.

You can then back calculate an approximation of the capacitance...I'd be reluctant to rely on a meter due to the nature of the lumped strays.
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