What is this inductor doing?

[martyh]

I traced this crossover that came with my Tannoy 2046 drivers. The 1191 part number on the board matches with a few systems that used the driver. The inductor values are what I measured with a meter and the rest of the component values are based on the markings on the parts.

Anyway, I’m just curious about the function of the 0.1 MH inductor parallel with the woofer in this diagram. Can anyone tell me what it is for?

Thanks,
Marty

 

[Cal Weldon]

Hi Marty,

Series Notch Filter Designer / Calculator Help

 

[system7]

I can elaborate. 1.1mH and 30uF/2.7R form a lowish crossover around 2kHz, slightly dependent on woofer DC resistance.

The additional 0.1mH adds a gentle notch to the 30uF and 2.7R shunt elements at 2.9kHz. Quite a nice technique when it all works out. Avoids bass cone-breakup sounds in the upper midrange which can be harsh and can also align phase nicely.

Alan Yates' Laboratory - VK2ZAY's Engineering Calculators - LCR Resonance

 

[martyh]

Thank you Cal, if I understand the link and what I found in a quick search it is part of a notch filter that is centered above the xo frequency.

 

[martyh]

I can elaborate. 1.1mH and 30uF/2.7R form a lowish crossover around 2kHz, slightly dependent on woofer DC resistance.

The additional 0.1mH adds a gentle notch to the 30uF and 2.7R shunt elements at 2.9kHz. Quite a nice technique when it all works out. Avoids bass cone-breakup sounds in the upper midrange which can be harsh and can also align phase nicely.

Alan Yates' Laboratory - VK2ZAY's Engineering Calculators - LCR Resonance

Thanks for the clarification. If I can find a calculator it would be neet to see what it is doing to the phase. The woofer to tweeter acoustic centers are about 1" apart. Dealing with cone breakup and aligning the phase with a few parts would be a really cool trick.

 

[sreten]

Thanks for the clarification. If I can find a calculator it would be neet to see
what it is doing to the phase. The woofer to tweeter acoustic centers are
about 1" apart. Dealing with cone breakup and aligning the phase with a
few parts would be a really cool trick.

Hi,

The free TinaTi SPICE emulator will calculate anything you want.

But if the x/o notch is aligned to a driver peak, you can't surmise
anything about the real acoustic phase output, for that you need
full driver specs and a completely different set of speaker tools :
FRD Consortium tools guide

rgds, sreten.