zobel

[Streets97f]

I'm trying to build a zobel circuit for a dual-coil 10" sub. The sub is 1.0mH and 4ohms, but is wired in parallel so the circuit sees 2 ohms. I don't know if I should us 2 ohms for the zobel calculation or use 4 ohms. With 2 ohms some pretty big cap values show up.

I would appreciate any help thanks.

[hooha]

When you say 4 Ohms you're referring to dual 4's right? So paralleling them will end in a nominal 2 Ohm impedance. You should go with the nominal impedance, which in this case would be 2 Ohms.

For a nice flat impedance, yes, it may take a large cap, but you may not have to go so big - the tweeter will pull the impedance down anyway.

Mark

[Streets97f]

Yes this is correct. The final impedance is 2 ohms.

Please explain then how i incorporate the tweeters in the calculation to choose the right caps.

Thanks

[hooha]

The proper way would be to do an impedance curve of the two units together to see just how much the woofer impedance is affected by the tweeter without impedance compensation.

Many times a zobel is not required, as an increase in impedance on the woofer may happen out of the woofer passband. This may be a desirable result as you would then have a natural decrease in output by the woofer at higher frequencies.

However, if the impedance increases too much within the passband, then a zobel of small parameters along with the added tweeter will tame the impedance of the woofer.

Mark

[rabbitz]

Shouldn't need a zobel for a sub woofer.