Why Are Inductors Needed?

[luckyduck]

I understand the use of electrical components placed in the signal path to pear off appropriate frequencies to the tweeter and mid-driver, but what is the role of inductors installed before the woofer? Why not let everything not captured by the speakers responsible for the remaining sound spectrum pass to the woofer untouched?

Thank you in advance.[]... Trying to further my education a little, so I thought thrusting my hand in the air and asking the teachers would be my best bet. [A]

[Don Richard]

The inductor keeps the higher frequencies from the woofer so that it only reproduces lows. The circuit elements preceding the tweeter allow it to reproduce only the highs.

This is done because the woofer does a poor job on the highs, and the tweeter cannot do the lows and will be damaged by the low frequency energy.

[jtnfoley]

For some theory: http://en.wikipedia.org/wiki/Inductor

Summarizing (lay terms, and within the limits of my limited understanding! I'm not an EE, but I play one at work sometimes [] ) Current changes in the time domain are converted to magnetic fields which collapse when the current decreases. The conversion to magnetic field (and back) is useful as a filter as rapid changes in current (i.e. high frequency) tend to be blocked by the sustained magnetic field in the inductor.

[Crossman]

Is is true that klipshorns do not need an inductor for the bass bin since it tops out at 400hz? If so can one biamp a khorn and amp the bass bin without the need of any type of crossover?

[artto]

Is is true that klipshorns do not need an inductor for the bass bin since it tops out at 400hz? If so can one biamp a khorn and amp the bass bin without the need of any type of crossover?

I can only speak from my own experience. The Khorns and other Klipsch Heritage speakers using the AA type crossover network have an inductor connected to the woofer. On the Belle for instance, at one time it was suggested that removing the inductor decreased a mid-bass hump in the frequency response. Whether or not this is audible kind of depends on your setup and recording being listened to. I disconnected the inductor on the Belle but the inductors are still in place on the KHorns. I did this primarily because in my system the Belle is used as a bridged center channel. And when you mix a stereo signal to mono, the bass typically gets stronger, so removing the inductor made some sense in this situation.

[jtkinney]

While it's true that there are limitations to what the woofer or horn can reproduce (upper freq. limit) the low pass filter (inductor) before

the woofer keeps it from trying to work at HF, which eliminates some distortion.

[JohnA]

[W]hat is the role of inductors installed before the woofer? Why not let everything not captured by the speakers responsible for the remaining sound spectrum pass to the woofer untouched?

The short answer is to reduce distortion.

First think Doppler Effect; train whistle pitch rises and then falls as the train passes.

Now imagine a big woofer reproducing low, loud bass and moving back and forth a great distance. Then, add a high frequency like a violin. Due to the cone motion, the violin sounds like "wee oooh, wee oooh, wee oooh. Not good. It's called intermodulation (IM) distortion.

An inductor can be used to roll off the highs going to any driver, so, sized right (and maybe with other components) it can reduce the woofer's IM distortion to inaudibility.

Another reason is that having 2 drivers reproducing the same sound at the same time can cause interference between them. You will get a rough response curve with lots of peaks and valleys where the 2 signals add and subtract.